# Antimalarial Plants Used across Kenyan Communities

Authors: Timothy Omara
Journal: Evidence-Based Complementary and Alternative Medicine
 (2020)

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## Abstract

Malaria is one of the serious health problems in Africa, Asia, and Latin America. Its treatment has been met with chronic failure due to pathogenic resistance to the currently available drugs. This review attempts to compile phytotherapeutical information on antimalarial plants in Kenya based on electronic data. A comprehensive web search was conducted in multidisciplinary databases, and a total of 286 plant species from 75 families, distributed among 192 genera, were retrieved. Globally, about 139 (48.6%) of the species have been investigated for antiplasmodial (18%) or antimalarial activities (97.1%) with promising results. However, there is no record on the antimalarial activity of about 51.4% of the species used although they could be potential sources of antimalarial remedies. Analysis of ethnomedicinal recipes indicated that mainly leaves (27.7%) and roots (19.4%) of shrubs (33.2%), trees (30.1%), and herbs (29.7%) are used for preparation of antimalarial decoctions (70.5%) and infusions (5.4%) in Kenya. The study highlighted a rich diversity of indigenous antimalarial plants with equally divergent herbal remedy preparation and use pattern. Further research is required to validate the therapeutic potential of antimalarial compounds from the unstudied claimed species. Although some species were investigated for their antimalarial efficacies, their toxicity and safety aspects need to be further investigated.


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## Body

## 1. Introduction

Globally, malaria continues to be in the top list of the major global health challenges. A global estimate of 655,000 malarial deaths was reported in 2010 of which 91% were in Africa and 86% of these were children under 5 years of age [1, 2]. Africa is particularly more susceptible, and conservative estimates cited that malaria causes up to 2 million deaths annually in Africa [3, 4]. The World Health Organization reported that about 2 billion people in over 100 countries are exposed to malaria, and the situation is exacerbated on the African continent which is characterized by limited access to health services and chronic poverty [5]. In East Africa and Kenya particularly, malaria remains endemic in the Lake Victoria basin and the coast with the country’s highest rate of infection at 27% (6 million cases) in 2015 from 38% in 2010 [6, 7]. The Kenyan population at risk of malaria as of 2016 was estimated at 100% [5]. Anopheles gambiae and A. funestus are the primary vectors of malaria in East Africa [8], while Plasmodium falciparum and P. vivax are the deadliest malarial parasites in sub-Saharan Africa.The misuse of chloroquine in the management of malaria has led to the development of chloroquine-resistant parasites worldwide [9]. In Kenya, the use of chloroquine has been discontinued as the first line treatment for malaria due to the prevalence of resistant P. falciparum strains [10, 11]. Artemisinin-based combination therapy (ACT) is currently the only available treatment option for malaria as the quinolines (quinine, chloroquine, and mefloquine) have been reported to cause cardiotoxicity, and the malarial parasites have already developed sturdy resistance to them [12, 13]. Unfortunately, resistance of P. falciparum to artemisinin has also been reported elsewhere [14].The Kenyan government has attempted to reduce malaria incidences in Kenya through several approaches including entomologic monitoring, insecticide resistance management, encouraging the population to sleep under insecticide-treated mosquito nets, intermittent preventive treatment for pregnant women, and indoor residual spraying [6, 7, 15, 16]. The situation has been made more complicated by the emergence of pyrethroid-resistant mosquitoes throughout Western Kenya which prompted the government to declare no spraying of mosquitoes between 2013 and 2016 [6].Malaria may manifest with relatively simple symptoms such as nausea, headache, fatigue, muscle ache, abdominal discomfort, and sweating usually accompanied by high fever [17]. However, at advanced stages, it can result in serious complications such as kidney failure, pulmonary oedema, brain tissue injury, severe anaemia, and skin discoloration [5, 18]. Conventional treatment is usually costly, and in rural Kenya just like in other parts of the world, the use of plants for either preventing or treating malaria is a common practice [3]. The current study attempted to gather comprehensive ethnobotanical information on various antimalarial plants and their use in Kenyan communities to identify which plants require further evaluation for their efficacy and safety in malaria management.


## 2. Methods

### 2.1. Literature Search Strategy and Inclusion and Exclusion Criteria

Relevant literature pertaining to antimalarial plants and their use in management of malaria and malarial symptoms in Kenya were sourced from Scopus, Web of Science Core Collection, PubMed, Science Direct, Google Scholar, and Scientific Electronic Library Online from November 2019 to February 2020 following procedures previously used [19–21]. The searches were performed independently in all the databases. Key search words such as malaria, vegetal, traditional medicine, ethnobotany, alternative medicine, ethnopharmacology, antimalarial, quinine, chloroquine, antimalarial activity, antiplasmodial activity, malaria management, and Kenya were used. All publishing years were considered, and reports with information on antimalarial or medicinal plants in Kenya were carefully screened. Thus, references contained within the returned scientometric results were assessed concerning their inclusion in the study, and further searches were carried out at the Google search engine using more general search terms, to broaden the search, as follows: words: malaria, plants, plant extract, vegetal, vegetal species, vegetal extract, traditional medicine, alternative medicine, complementary therapy, natural medicine, ethnopharmacology, ethnobotany, herbal medicine, herb, herbs, decoction, infusion, macerate, concoction, malaria fever, malaria incidence, and Kenya were used. The last search was done on 15th February 2020. The search outputs were saved wherever possible on databases, and the author received notification of any new searches meeting the search criteria from Science Direct, Scopus, and Google scholar. For this study, only full-text original research articles published in peer-reviewed journals, books, theses, dissertations, patents, and reports on antimalarial plants or malaria phytotherapy in Kenya written in English and dated until February 2020 were considered.Missing information in some studies particularly the local names, growth habit of the plants, and misspelled botanical names were retrieved from botanical databases: The Plant List, International Plant Names Index, NCBI taxonomy browser and Tropicos, and the Google search engine. Where a given species was considered as distinct species in different reports, the nomenclature as per the botanical databases took precedence. The traditional perception of malaria as well as the families, local names (Digo, Giriama, Kamba, Kikuyu, Kipsigis, Kuria, Luo, Markweta, Maasai, Nandi, and Swahili), growth habit, part (s) used, preparation, and administration mode of the different antimalarial plants were captured.


### 2.2. Data Analysis

All data were entered into Microsoft Excel 365 (Microsoft Corporation, USA). Descriptive statistical methods, percentages, and frequencies were used to analyze ethnobotanical data on reported medicinal plants and associated indigenous knowledge. The results were subsequently presented as tables and charts.


## 2.1. Literature Search Strategy and Inclusion and Exclusion Criteria

Relevant literature pertaining to antimalarial plants and their use in management of malaria and malarial symptoms in Kenya were sourced from Scopus, Web of Science Core Collection, PubMed, Science Direct, Google Scholar, and Scientific Electronic Library Online from November 2019 to February 2020 following procedures previously used [19–21]. The searches were performed independently in all the databases. Key search words such as malaria, vegetal, traditional medicine, ethnobotany, alternative medicine, ethnopharmacology, antimalarial, quinine, chloroquine, antimalarial activity, antiplasmodial activity, malaria management, and Kenya were used. All publishing years were considered, and reports with information on antimalarial or medicinal plants in Kenya were carefully screened. Thus, references contained within the returned scientometric results were assessed concerning their inclusion in the study, and further searches were carried out at the Google search engine using more general search terms, to broaden the search, as follows: words: malaria, plants, plant extract, vegetal, vegetal species, vegetal extract, traditional medicine, alternative medicine, complementary therapy, natural medicine, ethnopharmacology, ethnobotany, herbal medicine, herb, herbs, decoction, infusion, macerate, concoction, malaria fever, malaria incidence, and Kenya were used. The last search was done on 15th February 2020. The search outputs were saved wherever possible on databases, and the author received notification of any new searches meeting the search criteria from Science Direct, Scopus, and Google scholar. For this study, only full-text original research articles published in peer-reviewed journals, books, theses, dissertations, patents, and reports on antimalarial plants or malaria phytotherapy in Kenya written in English and dated until February 2020 were considered.Missing information in some studies particularly the local names, growth habit of the plants, and misspelled botanical names were retrieved from botanical databases: The Plant List, International Plant Names Index, NCBI taxonomy browser and Tropicos, and the Google search engine. Where a given species was considered as distinct species in different reports, the nomenclature as per the botanical databases took precedence. The traditional perception of malaria as well as the families, local names (Digo, Giriama, Kamba, Kikuyu, Kipsigis, Kuria, Luo, Markweta, Maasai, Nandi, and Swahili), growth habit, part (s) used, preparation, and administration mode of the different antimalarial plants were captured.


## 2.2. Data Analysis

All data were entered into Microsoft Excel 365 (Microsoft Corporation, USA). Descriptive statistical methods, percentages, and frequencies were used to analyze ethnobotanical data on reported medicinal plants and associated indigenous knowledge. The results were subsequently presented as tables and charts.


## 3. Results and Discussion

### 3.1. Antimalarial Plants Used in Kenya

In aggregate, 61 studies and reports identified 286 plant species from different regions of Kenya belonging to 75 botanical families distributed among 192 genera (Table1). Asteraceae (36.5%), Fabaceae (29.7%), Lamiaceae (24.3%), Euphorbiaceae (21.6%), Rutaceae (17.6%), and Rubiaceae (17.6%) were the most common plant families (Figure 1). The most frequently encountered species were Toddalia asiatica (L.) Lam (11 times), Aloe secundiflora Engl. (10 times), Azadirachta indica A. Juss, Carissa edulis (Forsk.) Vahl., Harrisonia abyssinica Olive (9 times each), Zanthoxylum chalybeum Engl. (8 times), Ajuga remota Benth., Rotheca myricoides (Hochst.) Steane and Mabb, Warburgia ugandensis Sprague (7 times each), Albizia gummifera (J. F. Gmel.), Erythrina abyssinica Lam. ex DC., Plectranthus barbatus Andrews, Rhamnus prinoides L.’Herit, Senna didymobotrya (Fresen) Irwin and Barneby, and Solanum incanum L. (6 times). One botanically unidentified plant (Ima) was reported by Kuria et al. [11]. Decoction of a whole lichenized fungi (Usnea species and Intanasoito in Maasai dialect) and Engleromyces goetzei P. Henn. fungi were also reported to be used in management of malaria in rural Kenya [22, 23].Table 1
Synopsis of medicinal plants used in the management of malaria in Kenya.
Plant familyBotanical nameLocal namePart(s) usedHabitPreparation modeReference(s)AcanthaceaeJusticia betonica L.ShikuduliAerial partsHerbDecoction[34, 35]AlliaceaeAllium sativum L.Kitungu saumu (Luo)RootsHerbCrushed, chewed[36]AloeaceaeAloe barbadensis Mill. (vera)Oldopai (Maasai)LeavesHerbNot specified[37]Aloe kedongensis ReynoldsOsukuroi (Maasai)Leaves, rootsHerbInfusion[3, 38–40]Aloe elgonica BullockNot reportedLeaves, rootsHerbDecoction[41]Aloe lateritia Engl.Kiiruma (Kikuyu)Leaves, rootHerbDecoction[3, 42]Aloe volkensii Engl.Osukuroi (Maasai)LeavesHerbDecoction[22]Caesalpinia volkensii HarmsMujuthi (Kikuyu)LeavesLianaDecoction[3, 11, 43, 44]AmaranthaceaeAchyranthes aspera L.Uthekethe (Kamba)Whole plantHerbNot specified[23, 45]Amaranthus hybridus L.Mchicha (Swahili)LeavesHerbDecoction[17, 46]Celosia schweinfurthiana Schinz.Not reportedNot specifiedShrubNot specified[47]Cyathula schimperiana non MoqNamgwetLeaves, rootsHerbDecoction[38, 40]Cyathula cylindrica MoqNg’atumyatRootsHerbDecoction[38, 40]Sericocomopsis hildebrandtii Schinz.Oloituruj-ilpeles (Maasai)RootsShrubDecoction[22, 48]AnacardiaceaeHeeria insignis Del.Mwamadzi (Swahili)Bark, stem barkTreeDecoction[17, 46]Lannea schweinfurthii (Engl.) Engl.MnyumbuBark, leavesShrubNot specified[49, 50]Ozoroa insignis DelileNot reportedNot reportedShrubNot specified[42]Rhus natalensis Bernh. ex KraussMuthigiu (Kikuyu)Root, stem, fruits, root barkTreeDecoction[3, 42, 49–51]Rhus vulgaris MeikleSungulaLeavesHerbDecoction[3, 42]Sclerocarya birrea (A. Rixh.) HochstOloisuki (Maasai)BarkTreeNot specified[49]Searsia natalensis (Bernh. ex C. Krauss)Olmisigiyioi (Maasai)LeavesHerbDecoction[34]AnnonaceaeUvaria acuminata Oliv.Mukukuma (Kamba)RootsShrubNot specified[50]Uvaria scheffleri DielsNot reportedLeavesLianaDecoction[17]ApiaceaeCentella asiatica (L.) Urb.Not reportedLeavesHerbDecoction[17]ApocynaceaeCarissa edulis (Forssk.) Vahl.Olamuriaki (Maasai), Mukawa (Kikuyu)Root, root barkShrubDecoction, inhale steam[3, 17, 34, 38, 40, 47, 48, 52, 53]Catharanthus roseus (L.) G. DonOlubinuNot specifiedHerbNot specified[47]Gomphocarpus fruticosus (L.) W. T. AitonKosirichRootHerbNot specified[54]Laudolphia buchananii (Hall.f) StapfMhonga (Swahili)LeavesLianaDecoction[17, 46]Mondia whiteiOgombo (Luo)RootsHerbChewed[42]Rauwolfia cothenNot reportedRoot barkShrubDecoction[17]Saba comorensis (Bojer ex A.D.C) PichonAbuno (Luo)Not specifiedHerbNot reported[42]AsclepiadaceaeCurroria volubilis (Schltr.) BullockSimatwetBarkLianaDecoction[38, 40]Periploca linearifolia Dill. & A. Rich.Muimbathunu (Kikuyu)BarkLianaDecoction[3, 44]AsteraceaeAchyrothalamus marginatus O. Hoffm.Not reportedLeavesHerbDecoction[55]Acmella caulirhiza Del.ShitutiAerial partsShrubDecoction[34, 56]Ageratum conyzoides L.Not reportedWhole plantHerbDecoction[56, 57]Artemisia afra JacqNot reportedLeavesShrubDecoction[41]Artemisia annua L.Not reportedLeavesShrubDecoction[42]Aspilia pluriseta Schweinf.RirangeraLeavesHerbDecoction[35]Bidens pilosa L.Nyanyiek mon (Luo)LeavesHerbDecoction[11, 37]Ethulia scheffleri S. MooreNot reportedLeavesHerbDecoction[58]Gutenbergia cordifolia Benth.Olmiakaru-kewon (Maasai)LeavesHerbDecoction[48]Kleinia squarrosaMungendya (Kamba)LeavesShrubInfusion[55]Launaea cornuta (Oliv and Hiern) C. JeffreyUthunga (Kamba)LeavesLianaInfusion/decoction[17, 46, 55]Microglossa pyrifolia (Lam.) O. KuntzeNyabung-Odide (Luo)Root, leavesShrubDecoction[34, 37, 38]Psiadia arabica Jaub. & PachNyabende winy (Luo)Not specifiedHerbNot specified[42]Psiadia punctulata (D.C.) VatkeOlobai (Maasai)RootsHerbNot specified[48]Sonchus schweinfurthii Oliv. & HiernEgesemi (Kuria)Not specifiedHerbNot specified[37]Schkuhria pinnata (Lam.) Kuntze ex ThellGakuinini (Kikuyu)Whole plantHerbInfusion[3, 23, 42, 44]Senecio syringitolia O. HoffmanReisa (Digo)LeavesHerbDecoction[17, 46]Solanecio mannii (Hook. f) C. JeffreyMaroo, marowo (Luo), LivokhoLeavesShrubDecoction[23]Sonchus luxurians (R.E. Fries) C. JeffreyKimogit (Nandi)RootsHerbDecoction[38]Sphaeranthus suaveolens (Forsk.) DCNjogu-ya-iriaWhole plantHerbInfusion, rubbed on the body[44, 52]Tithonia diversifolia (Hemsl.) GrayMaua madongo (Luo)LeavesShrubDecoction[3, 34, 42]Tridax procumbens L.Not reportedWhole plantHerbInfusion[17]Vernonia amygdalina Del.MusulilitsaLeavesShrubDecoction[17, 34, 42]Vernonia auriculifera (Welw.) HiernMuthakwaLeaves, roots, barkShrubInfusion, decoction[35, 37, 38, 41, 44]Vernonia brachycalyx O. Hoffm. SchreberIrisabakw (Kuria)LeavesHerbDecoction[37, 44, 58]Vernonia brachycalyx O. Hoffm. Lasiopa Lam.Olusia (Luo)LeavesHerbDecoction[37]Vernonia lasiopus O. Hoffm.Shiroho, MwathaLeaves, root barkShrubInfusion[23, 35, 44]BignoniaceaeKigelia africana (Lamk.) Benth.Omurabe, MorabeLeaves, bark, fruitsTreeDecoction[44, 58, 59]Markhamia lutea (Benth.) K. Schum.Lusiola, ShisimbaliBarkTreeDecoction[34, 47]Markhamia platycalyx SpragueSiala (Luo)Not specifiedTreeNot specified[42]Spathodea campanulata P. Beauv.Muthulio, MutsuriaLeavesTreeDecoction[34]BoraginaceaeEhretia cymosa ThonnMororwetLeaves, rootsShrubInfusion[38, 40]BurseraceaeCommiphora eminii EnglMukungugu (Kikuyu)Not specifiedTreeNot specified[3]Commiphora schimperi (Berg) Engl.Osilalei (Maasai), Dzongodzongo (Swahili)Inner bark, roots, stem barkTreeDecoction[17, 46, 48]CanellaceaeWarburgia salutaris (Bertol.F.) Chiov.Osokonoi (Maasai)BarkTreeDecoction[22, 37, 45]Warburgia stuhlmannii Engl.Not reportedStem barkTreeDecoction[17]Warburgia ugandensis Sprague subsp ugandensisMuthiga (Kikuyu)Stem bark, fruits, leavesTreeDecoction[3, 11, 22, 34, 43, 51, 54]CapparaceaeBoscia angustifolia A. Rich.Oloiroroi (Maasai)Inner bark fibres, stem barkTreeDecoction[42, 44, 48, 52]Boscia salicifolia Oliv.Mwenzenze (Kamba)Not specifiedTreeNot specified[49]Cadaba farinosa ForsskAkado marateng (Luo)Not specifiedShrubNot specified[42]CapparidaceaeCleome gynandra L.IsakiatLeaves, rootsHerbDecoction[40]CariaceaeCarica papaya L.Poipoi, Apoi (Luo)Leaves, roots, sapShrubInfusion, decoction[36]CelastraceaeMaytenus arbutifolia (A. Rich.) WilczekMuragaRoot barkShrubDecoction[44]Maytenus heterophylla (Eckl. & Zeyh.) N. RobsonMuragaRoot, root barkShrubDecoction[41, 44]Maytenus putterlickioides (Loes.) Excell & MendoncaMuthuthiRoot barkShrubDecoction[44]Maytenus senegalensis (Lam.) ExellMuthuthi (Kikuyu)Not specifiedShrubNot specified[3, 47]Maytenus undata (Thunb.) BlakelockMuthithioiRoot bark, leavesShrubDecoction[44]CleomaceaeCleome gynandra L.IsakiatLeaves rootsHerbDecoction[38]CombretaceaeCombretum illairii Engl.Mshinda arumeLeaves, root barkTreeDecoction[50]Combretum molle G. DonMuama, Kiama (Kamba)Bark, leavesTreeDecoction[17, 45]Combretum padoides Engl. & DielsMshinda arumeLeaves, rootsTreeDecoction[17, 46, 50, 60]Terminalia brownii Fresen.Muuku (Kamba)BarkTreeDecoction[55]Terminalia spinosa Engl.Not reportedBark, stem barkTreeDecoction, infusion[17, 61]CommelinaceaeAneilema spekei (C. B. Clarke)Enkaiteteyiai (Maasai)Whole plantLianaDecoction[22]Commelina forskaolii VahNot reportedNot specifiedHerbNot specified[47]CrassulaceaeKalanchoe lanceolata (Forsk.) Pers.Mahuithia (Kikuyu)Not specifiedHerbNot specified[3]CucurbitaceaeCucumis aculeatus Cogn.Gakungui (Kikuyu)LeavesClimberDecoction[3, 34, 42, 62]Cucumis prophetarum L.Chepsawoy (Kipsigis)Root tuberHerbDecoction[39]Gerranthus lobatus (Cogn.) JeffreyMgore manga (Digo)Leaves, rootsHerbDecoction[17, 46]Momordica foetida SchumachCheptenderet (Kipsigis)Leaves, rootsLianaDecoction, roasting[17, 38, 41]Momordica friesiorum Hams C. JeffreyLibobolaRoot tuberHerbDecoction[54]Zehneria minutiflora (Cogn.) C. JeffreyManereriat (Kimanererit)Leaves, rootsLianaDecoction[38]CyperaceaeCyperus articulatus L.NdagoTuberHerbInfusion[44]EbenaceaeEuclea divinorum HiernUswet (Markweta)Root barkTreeDecoction, use for brushing teeth[38, 47]Diospyros abyssinica (Hiern) F. White subsp. abyssinicaLusuiBarkTreeDecoction[41, 59]Diospyros scabraNot reportedBarkTreeDecoction[61]EuphorbiaceaeBridelia micrantha Baill. (Hochst).Mdungu (Digo)Leaves, bark, stem barkShrubDecoction[17, 46]Clutia abyssinica Jaub. & SpachMuthima mburi (Kikuyu)Leaves, root, root barkShrubDecoction[3, 38, 44]Croton dichogamus Pax.Oloiborrbenek (Maasai)Whole plantShrubDecoction[22, 38]Croton macrostachyus Hochst. ex Del.Mukinduri (Kikuyu)Leaves, root, barkTreeDecoction[34, 38, 56]Croton megalocarpoides Friis & M.G. GilbertOrmegweit (Maasai)BarkTreeDecoction[22]Croton megalocarpus Del.Not reportedNot specifiedTreeNot specified[3]Euphorbia inaequilatera Sond.Ogota KwembebaWhole plantShrubDecoction[35]Euphorbia meridionalis Bally & S. CarterEnkokuruoi (Maasai)StemClimberNot specified[22]Euphorbia tirucalli L.Kariria (Kikuyu)Not specifiedTreeNot specified[3]Flueggea virosa (Willd.) VoigtMukwambaRoot barkTreeDecoction[50]Flueggea virosa (Roxb.ex Willd.) RoyleMkwamba, mteja (Swahili)Aerial parts, root barkShrubDecoction[17, 34]Neoboutonia macrocalyx PaxMutuntukiLeaves, stem barkTreeDecoction[44, 53]Phyllanthus sepialis Müll. Arg.Not reportedLeavesShrubDecoction[34]Ricinus communis L.Kivaiki (Kamba)Root, seeds, leavesShrubDecoction, topical[17, 38, 46]Sapium ellipticumAchak (Luo)Not specifiedShrubNot specified[42]Suregada zanzibariensis BaillNot reportedRoot barkShrubDecoction[17]FabaceaeAbrus precatorius L. ssp africanus VerdcNdirakaluLeavesHerbNot specified[42, 50]Acacia hockii De Wild.Eluai (Maasai)Root barkTreeDecoction[48]Acacia mellifera (M.Vahl) Benth.Oiti (Maasai), Muthiia (Kamba)Stem bark, root, pithTreeDecoction[11, 22, 48, 52, 63]Acacia nilotica (L.) Willd.ex DelileOlkirorit, Ol-rai (Masaai)Bark, rootTreeDecoction[22, 37, 53, 64]Acacia oerfota (Forssk.) Schweinf.Not reportedRootTreeNot reported[63]Acacia seyal DelileMgunga (Digo)RootTreeDecoction[17]Acacia tortilis (Forssk.) HayneOltepesi (Maasai)Sap, rootsTreeTaken directly, decoction[22, 48]Albizia amara (Roxb.) Boiv.MwiradathiStem barkTreeDecoction[44]Albizia anthelmintica Brongn.Kyoa (Kamba)Root, barkTreeDecoction[17, 22, 63]Albizia coriaria Welw ex OliverOmubeliMultiple partsTreeDecoction[42, 47, 57, 65]Albizia gummifera (J.F. Gmel.)Seet (Nandi)Root, stem barkTreeDecoction[23, 34, 38, 42, 44, 66]Albizia zygia (DC) J.F. Macbr.Ekegonchori (Kuria)Not specifiedTreeNot specified[37]Cassia didymobotrya Fres.Irebeni (Kuria), MuraoLeaves, roots, root barkShrubInfusion, decoction[37, 38, 40, 44]Cassia occidentalis L.Mnuka uvundo (Swahili)Leaves, rootsHerbDecoction[11, 17, 46]Dichrostachys cinereal L.Chinjiri (Digo)rootsTreeDecoction[17]Erythrina abyssinica Lam. ex DC.Omutembe (Kuria), Muhuti (Kikuyu)Root, barkTreeDecoction[3, 23, 34, 37, 38, 42]Indigofera arrecta A. RichNot reportedRootsHerbDecoction, chew directly[41]Mucuna giganteaOgombo (Luo)Not specifiedLianaNot specified[42]Senna didymobotrya (Fresen) Irwin & BarnebyOsenetoi (Maasai)Roots, leaves, bark, stemShrubDecoction[3, 23, 34, 41, 42, 67]Senna occidentalis (L.) LinkImbindiRootsShrubDecoction[34, 47]Tamarindus indica L.Muthumula (Kamba), Mkwadzu (Swahili)Bark, fruits, roots, leavesTreeDecoction, fruit eaten[17, 46, 47, 54]Tylosema fassoglenseNot reportedTuberClimberNot specified[56]HydnoraceaeHydnora abyssinica Schweinf.Muthigira (Kikuyu)Not specifiedHerbNot specified[3]HypericaceaeHarungana madagascariensis Lam. ex Poir.MusilaStem barkTreeDecoction[17, 34, 42]IcacinaceaePyrenacantha malvifolia Engl.Empalua (Maasai)RootsClimberNot specified[22]LamiaceaeAjuga integrifolia Buch. Ham.Imbuli yumtakhaAerial partsHerbDecoction[34]Ajuga remota Benth.Wanjiru (Kikuyu)Leaves, roots, whole plantHerbDecoction[3, 11, 23, 38, 44, 68, 69]Clerodendrum johnstonii OlivSingoruet (Nandi)LeavesShrubInfusion[34, 38]Fuerstia africana T.C.E.Fr.Kwa matsai, aremo (Luo)Aerial parts, leaves, whole plantHerbDecoction, infusion[34, 38, 44, 48, 65]Hoslundia opposita Vahl.Cheroronit, Cherungut (Nandi)Leaves, whole plantShrubDecoction[17, 38, 46, 50]Leucas calostachys OlivBware (Luo), LumetsaniLeaves, roots, aerial partsShrubDecoction[34, 37, 38]Leucas martinicensis (Jacq.) Ait.f.Chepkari (Nandi)FlowersHerbInfusion[38]Leonotis mollissima GuerkeNyanyondhi (Luo), Orbibi (Maasai)Leaves, rootsShrubDecoction[23, 37, 38]Leonotis nepetifolia (R. Br) Ait.f.Kipchuchuniet (Kipsigis)Not specifiedShrubDecoction[47, 70]Ocimum basilicum L.Sisiyat (Nandi)LeavesHerbDecoction[23, 46]Ocimum balansae Briq.Not reportedLeavesHerbDecoction[17]Ocimum gratissimum L. Suave wiild, O. tomentosum Oliv.Mukandu (Kamba)LeavesHerbDecoction[17, 23]Ocimum kilimandscharicum GuerkeMutaa (Kamba)Aerial partsHerbInhale steam[3, 34, 56]Ocimum lamiifolium BenthNot reportedRootsShrubDecoction[38]Ocimum suave WilldMurihani (Giriama)LeavesHerbDecoction[17, 46, 71]Plectranthus barbatus AndrewsKan’gurwet (Markweta)LeavesShrubInfusion, decoction[17, 34, 42, 46, 56, 58]Plectranthus sylvestris GurkeNot reportedLeavesHerbNot specified[58]Rotheca myricoides (Hochst.) Steane and Mabb (Clerodendrum myricoides (Hochst.) Vatke)Olmakutukut (Maasai), Munjuga iria (Kikuyu)Roots, leaves, root barkShrubDecoction[17, 34, 38, 42, 44, 48, 67]LauraceaeOcotea usambarensis Engl.Muthaiti (Kikuyu)Root barkTreeInfusion[3, 44]LoganiaceaeStrychnos henningsii GilgMuteta (Kamba, Kikuyu)Roots, leaves, stem barkTreeDecoction[3, 11, 44, 47, 55, 67]MalvaceaeAdansonia digitata L.Mbamburi (Swahili)LeavesTreeDecoction[17, 46]Azanza gackeana (F. Hoffm.) Excell & HillcoatMutoo (Kikuyu)Not specifiedTreeNot specified[3]Grewia bicolor JussEsiteti (Maasai)Not specifiedShrubNot specified[47]Grewia hainesiana HoleNot reportedLeavesShrubDecoction[17]Grewia hexamita BurretMkone (Digo)Roots, leavesShrubDecoction[46]Grewia plagiophylla K. SchumMkone (Digo)Bark, leavesNot specified[50]Grewia trichocarpa (Hochst) ex A. Rich.Cone (Digo)RootsShrubDecoction[17, 41, 46]Pavonia kilimandscharica GurkeChemanjililiet, Chepsabuni (Nandi)RootsHerbDecoction[38]Sida cordifolia L.Menjeiwet (Nandi)LeavesShrubInfusion[38]MeliaceaeAzadirachta indica A. JussMuarubaini (Kamba)Leaves, roots, barkTreeDecoction, inhalation, topical[3, 11, 17, 36, 43, 50, 54, 55, 72]Azadirachta indica (L) Burm.Mkilifi (Digo)Leaves, roots, root barkTreeDecoction[46, 73]Ekebergia capensis Sparrm.Olperre-longo (Maasai)BarkTreeDecoction[3, 48]Melia azedarach L.MwarubaineNot specifiedTreeNot specified[47]Melia volkensii L.Mukau (Kamba)BarkTreeDecoction[55]Melia azedarach L.Mwarubaini (Nandi)Leaves, barkTreeDecoction[34, 38, 42]Trichilia emetica Vahl.MunyamaBarkTreeDecoction[34, 72]Turraea mombassana C. DCOnchani Orok (Maasai)Leaves, root, fruitsShrubDecoction[67]Turraea robustaNot reportedRoot barkShrubDecoction[49]MelianthaceaeBersama abyssinica Fres.Kibuimetiet (Nandi)Root bark, bark, seedsTreeDecoction[38, 41]MenispermaceaeCissampelos mucronata A. Rich.MukoyeRootClimberRoot chewed[17, 34, 74, 75]Cissampelos pareira L.Karigi munanaRoot, root barkLianaDecoction[39]MoraceaeFicus bussei Warb ex Mildbr and BurretMgandi (Digo)Roots, leavesTreeDecoction[17, 46]Ficus cordata ThunbOladardar (Maasai)Branches, roots, stemTreeDecoction[67]Ficus sur. ForsskOmoraStem barkTreeDecoction[35]Ficus thonningii BlumeMutotoStem barkTreeDecoction[34]MyricaceaeMyrica salicifolia A. Rich.MurimaRoot barkTreeDecoction[44]MyrsinaceaeEmbelia schimperi VatkeKibong'ong'inik (Nandi)SeedsTreeDecoction[38]Maesa lanceolata ForsskKatera (Luo), Kibabustanyiet (Nandi)Roots, fruits, seeds, barkShrubDecoction[22, 34, 38, 76]MyrtaceaeEucalyptus globulus Labil.Mubau (Kikuyu)Not specifiedTreeNot specified[3]Psidium guajava L.Mapera (Luo)Leaves, fruitsTreeDecoction[36]OleaceaeJasminum floribunda R.Br.Not reportedRootHerbDecoction[41]Jasminum fluminense Vell.KipkoburoBark, stem, root tuberVineNot specified[77]Olea capensis L.Mutukhuyu, MucharageStem barkTreeDecoction[41, 44]Olea europaea L.Oloirien (Maasai)Inner/stem barkTreeDecoction[3, 22, 44, 45, 48]Ximenia americana L.Olamai (Maasai)LeavesTreeDecoction[47]OnagraceaeLudwigia erecta (L.) HaraMungeiWhole plantHerbInfusion, decoction[44, 52]OpiliaceaeOpilia campestris Engl.Enkirashai (Maasai)RootsShrubDecoction[22]OxalidaceaeOxalis corniculata L.Nyonyoek (Nandi)Whole plantHerbDecoction[38]PapilionaceaeCajanus cajan Millsp.Mucugu (Kikuyu)Not specifiedHerbNot specified[3]Dalbergia lactea VatkeMwaritha (Kikuyu)Not specifiedShrubNot specified[3]Ormocarpum trachycarpum (Taub.) HarmsMuthingii (Kamba)Bark, leavesShrubDecoction[52, 58]Rhynchosia hirta (Andrews) Meikle & Verdc.Tilyamook (Nandi)RootsLianaDecoction[38]Stylosanthes fruticosa (Retz.) AlstonKalaa (Kamba)Leaves, whole plantHerbInfusion[55]PassifloraceaePassiflora ligularis A. Juss.Hondo (Kikuyu)Not specifiedShrubNot specified[3]PiperaceaePiper capense L.f.Olerrubaat (Maasai)RootsHerbDecoction[48]PittosporaceaePittosporum lanatum Hutch. & BruceMunyamati (Kikuyu)Not specifiedHerbNot specified[3]Pittosporum viridiflorum SimsMunatiStem barkTreeDecoction[34, 44, 52]PoaceaePennisetum hohenackeri Hochst. ex SteudOlmakutian (Maasai)Bark, branches, rootsGrassDecoction[67]Rottboellia exaltata L.f.Mpunga (Digo)LeavesHerbDecoction[17, 46]Sporobolus stapfianusNot reportedNot specifiedHerbNot specified[45]PodocarpaceaePodocarpus latifolius (Thunb.) R.Br. ex Mirb.Enchani-enkashi (Maasai)RootsTreeDecoction[48]PolygonaceaeRumex abyssinicus Jacq.ShikachiLeavesHerbDecoction[34]Rumex steudelii Hochst ex A. RichAlukhavaRootsHerbDecoction[34]PolygalaceaeSecuridaca longifolia Poepp.Not reportedRootsTreeDecoction[17]Securidaca longipedunculata Fres.Mzigi (Digo)Roots, bark, leavesShrubDecoction[46]PrimulaceaeMyrsine africana L.Oseketeki (Maasai)Seeds, fruits, roots, multiple partsShrubDecoction[54, 67]RahmnaceaeRhamnus prinoides L.’HeritOrkonyil (Maasai)Roots, root barkShrubDecoction[3, 11, 35, 38, 44, 48, 69, 78]Rhamnus staddo A. RichOrkokola (Maasai), Ngukura (Kikuyu)Root bark, stem barkShrubDecoction[3, 11, 35, 44, 48, 69]Scutia myrtina (Burm. f.) KurzOsanankoruri (Maasai)Not specifiedShrubNot specified[3]RanunculaceaeClematis brachiata Thunb.Olkisusheeit (Maasai)Roots, root barkLianaDecoction[44, 48]RhizophoraceaeCassipourea malosana (Baker) AlstonMuthathi (Kikuyu)Not specifiedTreeNot specified[3]RosaceaePrunus africana (Hook. f.) KalkmanOrkujuk (Maasai), Muiri (Kikuyu)Bark, root, stem, stem barkTreeDecoction[3, 38, 44, 79, 80]Rubus pinnatus Wild.ButunduliLeaves, bark, fruitsShrubDecoction[3, 34]RubiaceaeAganthesanthemum bojeri Klotzsch.KahithimaWhole plantHerbNot specified[50]Agathisanthenum globosum (Hochst. ex A. Rich.) Bremek.Chivuma nyuchi (Digo)RootsHerbDecoction[17, 46]Canthium glaucum Hiern.Mhonga/Mronga (Digo)FruitsShrubDecoction[17, 46]Gardenia ternifolia subsp. JovistonatisKibulwaFruitsShrubDecoction[54]Keetia gueinzii (Sond.) BridsonMugukuma (Kikuyu)Not specifiedShrubNot specified[3]Pentanisia ouranogyne S. MooreChungu (Digo)RootsHerbDecoction[17, 46]Pentas bussei K. KrauseNot reportedRoot barkShrubDecoction[17]Pentas longiflora Oliv.Muhuha (Kikuyu), Cheroriet (Nandi)Bark, fruits, leaves, rootsShrubDecoction, rub on skin[3, 17, 38, 41, 61]Pentas lanceolata (Forssk.) DeflersOlkilaki-olkerr (Maasai)Root barkHerbDecoction[48]Rubia cordifolia L.Urumurwa (Kuria)Not specifiedHerbNot specified[37]Spermacoce princeae (K. Schum.) Verdc.OmonhabieboWhole plantHerbDecoction[35]Vangueria madagascariensisGmel (Vangueria acutiloba Robyns)MubiruStem barkShrubDecoction[44]Vangueria volkensii K.Schum.Kimoluet (Nandi)RootsShrubDecoction[38, 47]RutaceaeCitrus aurantiifolia (Christm.) SwingleMutimu (Kikuyu)Not specifiedTreeNot specified[3]Citrus limon (L.) Burm.f.Ndim (Luo)Fruits, leavesTreeEaten, decoction[36]Clausena anisata (Willd) Hook. f. ex Benth.Mtondombare (Digo), MukibiaLeaves, roots, bark, root barkShrubDecoction[17, 34, 41, 44, 46]Fagaropsis angolensis (Eng.) H.M. GardnerMurumu, mukuriampunguLeaves, roots, stem barkTreeDecoction[3, 23, 38, 44, 53]Fagaropsis angolensis (Eng.) DaleMukaragati (Kikuyu)Leaves, rootsTreeDecoction[3, 17, 46]Fagaropsis hildebrandtii (Engl.) Milne-Redh.Muvindavindi (Kamba)LeavesTreeDecoction[3, 81]Harrisonia abyssinica OliveOsiro (Luo), Orongoriwe (Kuria)Leaves, roots, root barkTreeDecoction[17, 23, 37, 44, 46, 47, 54, 82, 83]Teclea nobilisNot reportedStem barkShrubDecoction[11, 45]Teclea simplicifolia (Engl.) VerdoornMutuiu (Kamba), Munderendu (Kikuyu)Leaves, roots, stem barkShrubDecoction[3, 17, 44, 46, 55]Toddalia asiatica (L.) LamMururue (Kikuyu), Oleparmunyo (Maasai)Roots, root bark, leaves, fruits (multiple parts)ShrubDecoction[3, 11, 17, 44, 45, 47, 58, 59, 62, 67, 84]Zanthoxylum chalybeum Engl.Oloisuki (Maasai)Stem bark, root barkTreeDecoction[3, 17, 44, 46, 55, 61, 71, 85]Zanthoxylum gilletii (De Wild.) P.G. WatermanShihumba/ShikumaBarkTreeDecoction[34, 86]Zanthoxylum usambarense (Engl.) KokwaroOloisuki (Maasai)Root, fruits, bark, leaves, stemTreeDecoction[3, 11, 67, 78, 85]SalicaceaeDovyalis abyssinica (A. Rich.) WarbKaiyaba (Kikuyu)Leaves, rootsShrubDecoction[3, 38]Dovyalis caffra (Hook. f. & Harv.) WarbMukambura (Kikuyu)Not specifiedShrubNot specified[3]Flacourtia indica (Burm.f) Merr.Mtondombare (Digo)Roots, barkShrubDecoction[17, 46]Trimeria grandifolia (Hochst.) WarbOledat (Maasai)RootsShrubDecoction[3, 38, 47]SalvadoraceaeSalvadora persica L.Mukayau (Kamba)Root, stemShrubDecoction; prepared with salt and milk[22, 51, 63]SantalaceaeOsyris lanceolata Hochst. & SteudelOlosesiai (Maasai), muthithii (Kikuyu)Not specifiedShrubNot specified[3]SapindaceaeAllophylus pervillei Blume.Mvundza kondoLeaves, roots, barkShrubDecoction[50]Cardiospermum corundumNot reportedNot specifiedShrubNot specified[23]Pappea capensis (Spreng) Eckl. & Zeyh.Muba (Kikuyu), Enkorr irri (Maasai)BranchesShrubDecoction[3, 48]SapotaceaeManilkara butegiAnonBarkShrubDecoction[54]Mimusops bagshawei S. MooreLolwet (Nandi)Leaves, barkTreeDecoction[38]SolanaceaePhysalis peruviana L.MayengoLeavesShrubInhale steam[34]Solanum aculeastrum DunalMutura (Kikuyu)Not specifiedShrubNot specified[3]Solanum incanum L.Mutongu (Kamba), Entulelei (Maasai)Roots, leaves, root barkShrubDecoction[17, 34, 37, 44, 46, 87]Solanum taitense VatkeEntemelua (Maasai)RootsShrubChewed directly[22]Withania somnifera (L.) DunalMurumbae (Kikuyu)Root barkShrubDecoction[3, 44]UlmaceaeChaetacme aristate PlanchNot reportedRootsShrubDecoction[41]UrticaceaeUrtica massaica Mildbr.Thabai (Kikuyu)Aerial partsHerbDecoction[3, 35]VerbenaceaeClerodendrum eriophyllum GuerkeMuumbaRoot barkShrubDecoction[44, 52]Lantana camara L.Ruithiki, Mukenia (Kikuyu)LeavesShrubDecoction[3, 73]Lantana trifolia L.Ormokongora (Maasai)LeavesShrubDecoction[34, 72]Lippia javanica (Burm.f.) SprengAngware-Rao (Luo)RootsHerbNot specified[37, 58]Premna chrysoclada (Bojer) GürkeMvumaRoots, leavesHerbNot specified[50]VitaceaeCissus quinquangularis L.Not reportedNot specifiedHerbNot specified[45]Cyphostemma maranguense (Gilg) Desc.Mutambi (Kikuyu)Not specifiedHerbNot specified[3]Rhoicissus tridentata (L.f.) Wild & DrumNdurutua (Kikuyu)Bark, rootsShrubDecoction[3, 34, 38, 62]XanthorrhoeaceaeAloe deserti A. BergerNgolonje (Digo)LeavesHerbDecoction, infusion[17, 46]Aloe macrosiphon Bak.Golonje (Giriama)LeavesHerbInfusion[46]Aloe secundiflora Engl.Osukuroi (Maasai), Kiluma (Kamba)Leaves, leaf sap (exudate)HerbInfusion, decoction[11, 17, 34, 43, 44, 46, 58, 78, 88, 89]Aloe vera (L) Webb.Alvera (Digo)LeavesHerbInfusion[17, 46]Rhoicissus revoilliRabongo (Luo)ZingiberaceaeZingiber officinaleTangawizi (Luo)RootsHerbChewed[36]ZygophyllaceaeBalanites glabrus Mildbr. & Schltr.Orng’osua (Maasai)Not specifiedTreeNot specified[22]Balanites glabra Mildbr. & Schltr.Olng’osua (Maasai)BarkShrubDecoction[22]Balanites aegyptiaca (L.) Del.Olngosua (Maasai)BarkShrubDecoction[48]Language is also known as Kikamba. Local names with language(s) not indicated are sometimes a blend of Kiswahili and other local languages or were not specified by the authors. Decoction involves boiling a plant part in water. Infusion entails soaking of a plant part in water.Figure 1
Major botanical families from which antimalarial remedies are obtained in Kenya.Some of the plants such asAcacia mellifera has been reported for treatment of malaria in Somalia [24], Albizia coriaria Welw. ex Oliver, Artemisia annua L., Momordica foetida Schumach, Carica papaya L., and Catharanthus roseus (L.) G. Don in Uganda [25, 26], Cameroon [27], and Zimbabwe [28], Clematis brachiata and Harrisonia abyssinica Oliv in Tanzania [29] and South Africa [30], Artemisia afra in Ethiopia [31], and Tamarindus indica L., Carica papaya L., and Ocimum basilicum L. in Indonesia [32].


### 3.2. Growth Habit, Part(s) Used, Preparation, and Administration of Antimalarial Plants

Antimalarial plants used in Kenya are majorly shrubs (33.2%), trees (30.1%), and herbs (29.7%) (Figure2), and the commonly used plant parts are leaves (27.7%) and roots (19.4%) followed by bark (10.8%), root bark (10.5%), and stem bark (6.9%) (Figure 3). Comparatively, plant parts such as fruits, seeds, buds, bulbs, and flowers which have reputation for accumulating phytochemicals are rarely used, similar to reports from other countries [26, 28, 33].Figure 2
Growth habit of antimalarial plants used in Kenyan communities as per ethnobotanical surveys.Figure 3
Frequency of the reported plant parts used for preparation of antimalarial remedies in Kenya.The dominant use of leaves presents little threat to the survival of medicinal plants. This encourages frequent and safe utilization of the plants for herbal preparations. Roots and root structures such as tubers and rhizomes are rich sources of potent bioactive chemical compounds [33], but their frequent use in antimalarial preparations may threaten the survival of the plant species used. For example, Zanthoxylum chalybeum and African wild olive (Olea europaea) have been reported to be threatened due to improper harvesting methods [2]. Thus, proper harvesting strategies and conservation measures are inevitable if sustainable utilization of such medicinal plants are to be realized.Antimalarial remedies in Kenya are prepared by different methods. These include decoctions (70.5%), infusions (5.4%), ointments and steaming (1.3%), and roasting (0.3%). Preparation of antimalarial remedies from dry parts of one plant or several plants and ashes by using grinding stones was reported [38]. Burning, chewing, heating/roasting, pounding, and boiling or soaking in hot or cold water and milk were reported, and these are then orally administered as is the case with Western medicine [38]. Preparations for application onto the skin such as ointments, poultices, and liniments are frequently percutaneous, by rubbing or covering which are occasionally complimented by massage [38]. Rarely are antimalarial remedies administered through the nasal route. Fresh solid materials are eaten and chewed directly upon collection or after initial pounding/crushing. Dry plant materials are smoked and inhaled. These findings corroborate observations in other countries [33, 90–92].Malaria is caused by protozoan intracellular haemoparasites, and its treatment entails delivering adequate circulating concentration of appropriate antiprotozoal chemicals. The oral route is a convenient and noninvasive method of systemic treatment as it permits relatively rapid absorption and distribution of active compounds from herbal remedies, enabling the delivery of adequate curative power [93]. In addition, potential risk of enzymatic breakdown and microbial fermentation of active chemical entities may prompt the use of alternative routes of herbal remedy administration like inhalation of the steam or rubbing on the skin.In this survey, it was noted that few plant species are used for management of malaria simultaneously in different locations. This could probably be attributed to the abundant distribution of the analogue active substances among species, especially belonging to family Asteraceae, Euphorbiaceae, Fabaceae, Meliaceae, Rubiaceae, and Rutaceae. Differences in geographical and climatic conditions may also influence the flora available in a given region. However, some plants have a wider distribution and therefore are used by most communities [34].


### 3.3. Perception, Prevention, and Treatment of Malaria and Its Symptoms

In rural Kenya, some believe thatesse (malaria in native Tugen dialect) is caused by Cheko che makiyo (fresh unboiled milk), dirty water, ikwek (vegetables such as Solanum nigrum and Gynadropis gynadra) [54], mosquito bites, or cold weather [42]. Thus, burning of logs and plants such as Albizia coriaria with cow dung, Azadirachta indica (L) Burm (fresh leaves), Ocimum basilicum L., Ocimum suave Willd. (fresh leaves), and Plectranthus barbatus Andr. (ripe fruits or seeds) are done to keep mosquitoes away [17, 42]. Artemisia annua L. is planted in the home vicinity or near the bedroom window to repel mosquitoes believed to cause malaria [42].Except in the case of life-threatening illnesses or where there is concern that there may be some supernatural forces in the aetiology of the disease, malaria and its symptoms (periodic fever, sweating, headache, backache, and chills) are treated primarily using decoctions and infusions of plants. Whenever it is thought that malaria is due to supernatural forces, diviners (such asOrgoiyon among the Tugen and Oloiboni among the Maasai) are consulted [94]. Croton dichogamus Pax though used for normal malaria treatment is used by Oloiboni for treatment of malaria or other ailment(s) thought to be due to witchcraft [22]. According to indigenous diagnoses, malaria is due to the presence of excess bile in the body, so the bile has to be expelled before healing can take place. Thus, purgation is regarded as the key treatment regimen for malaria [22, 54].On the basis of this knowledge, different forms of herbal medications are prescribed according to the severity of the illness. Treatment of malaria is based on a number of interlinked elements: beliefs related to causation, the action or effectiveness of “modern” medicines, and the availability of plant treatments [54]. Salvadora persica L. is used for management of malarial colds, while Aneilema spekei (C. B. Clarke) is used for prevention of malaria fever [22]. The whole plant is mixed with other herbs in milk and sprinkled onto the patient. This is often administered by an Oloibon among the Maasai [22].Though single plant parts are often used, more than one plant part, for example, decoctions from a mixture of roots ofPlectranthus sylvestris together with those of Cassia didymobotrya and Clerodendrum johnstonii may be used as a remedy for malaria and headache [52]. Acacia species stem bark was reported to be used as a first treatment and is usually prepared as an overnight cold-water infusion, and then 40 ml is taken three times a day [11]. A follow-up medication would involve taking a decoction made from powders of Aloe species (leaf juice), Rhamnus staddo (stem or root bark), Clerodendrum myricoides (root bark), Warburgia ugandensis, Teclea nobilis (stem barks), and Caesalpinia volkensii, Ajuga remota Benth, Rhamnus prinoides, and Azadirachta indica leaves [11]. For this, 40 ml is taken thrice a day for 5 days.The popular method of preparation as decoctions and concoctions suggest that the herbal preparations may only be active in combination, due to synergistic effects of several compounds that are inactive singly [95]. It is possible that some of the compounds that are inactive in vitro could exhibit activity in vivo due to enzymatic transformation into potent prodrugs [96] as reported for Azadirachta indica extracts [97].


### 3.4. Adverse Side Effects, Antidotes, and Contraindications of Medicinal Plants in Kenya

In traditional context, the pharmacological effect of medicinal plants is generally ascribed to their active and “safe” content that will only exert quick effect when taken in large quantities [22, 33]. Most reviewed reports in this study did not mention the side effects of antimalarial preparations. Nevertheless, herbal preparations from some antimalarial plants were reported to induce vomiting, diarrhea, headache, and urination [22, 54] (Table 2). This may be due to improper dosage, toxic phytochemicals, or metabolic by-products of these preparations [22].Table 2
Side effects, antidotes, and contraindications of medicinal plants used for traditional management of malaria in Kenya.
PlantSide effectsAntidote(s)ContraindicationReference(s)Albizia anthelmintica Brongn.Induces vomiting, diarrhea, and bile release from the gall bladderNot reportedPregnant women[22]Aloe volkensii L.Induces vomitingNot reportedChildren[22]Balanites glabrus Mildbr. & Schltr.Induces vomiting, diarrhea, and bile release from the gall bladderNot reportedPregnant women[22]Croton megalocarpoides Friis & M.G. GilbertStomachache, induce vomiting, and bile release from the gall bladderNot reportedNot reported[22]Euphorbia meridionalis Bally & S. CarterInduces diarrhea as a means of cleansing the bodyTaken with goat or sheep soupNot reported[22]Momordica friesiorum Hams C. JeffreyInduces vomiting and bile release from the gall bladderNot reportedNot reported[54]Opilia campestris Engl.Induces vomiting and bile release from the gall bladderMixed with soupNot reported[22]Pyrenacantha malvifolia Engl.Induces vomitingNot reportedPregnant women[22]Salvadora persica L.Induces vomiting and bile releaseMilk, saltNot reported[22]Sericocomopsis hildebrandtii Schinz.Stomachache, weight loss through induced vomiting, and bile release from the gall bladderMilkPregnant women[22]However, purgation and emesis are interpreted as signs that malaria is leaving the body and that the healing process has begun [22, 54]. It is reasonable that some side effects might also be masked through the use of more than one plant (or plant parts) especially for bitter remedies (such as Ajuga remota Benth.) [11, 38]. However, some herbalists are known to use more than one plant (plant parts) as a trick of keeping the secrecy of their formula [11]. Boiling of plant parts in goat fat, meat bone broth (as is done for Carissa edulis), taking decoctions mixed with milk (for Rhamnus prinoides), and mixing remedies with milk and salt for Salvadora persica L. [22] could serve as antidotes for potential side effects from use of the herbal preparations as reported elsewhere [33]. Some of the plants reported in this study such as Ajuga integrifolia and Croton macrostachyus were reported in Ethiopia to cause vomiting, nausea, headache, urination, and diarrhea when used for management of malaria [33]. Because the outcome of the treatment remains generally unclear due to lack of feedback from patients, herbalists rely on anecdotal reporting as far as efficacy and side effects are concerned.Some antimalarial plants were reported as contraindicated to pregnant women and children (Table2). Gathirwa et al. [50] reported that the posology of antimalarial herbal preparations in Kenya sometimes is dictated by the plant to be used, the traditional herbalist, the sex and the age of the patient, reiterating that pregnant women and children are often given lower dosages compared to other adults. This indicates the existence of research gaps with regard to the potential toxicities and corresponding counteracting mechanisms of antimalarial plants in Kenya. This gap represents a barrier to effective development and exploitation of indigenous antimalarial plants. In essence, some of the plants listed are reported to exhibit marked toxicity. Teclea simplicifoli (roots) is regarded to be poisonous by rural Kenyans [98]. Catharanthus roseus (L.) G. Don is another such plant known to house neurotoxic alkaloids [99]. Vincristine and vinblastine in this plant are highly cytotoxic antimitotics that block mitosis in metaphase after binding to mitotic microtubules [100]. Side effects such as kidney impairment, nausea, myelosuppression, constipation, paralytic ileus, ulcerations of the mouth, hepatocellular damage, abdominal cramps, pulmonary fibrosis, urinary retention, amenorrhoea, azoospermia, orthostatic hypotension, and hypertension [101–103] have been documented for antitumor drugs vincristine and vinblastine derived from this plant. These observations could partly explain why some antimalarial herbal preparations in Kenya are ingested in small amounts, applied topically, or are used for bathing. This gives a justification for the investigation of the plants for their potential toxicity.


### 3.5. Other Ethnomedicinal Uses of Antimalarial Plants Used in Rural Kenya

Most of the antimalarial plant species identified are used for traditional management of other ailments in Kenya and in other countries.Ajuga remota Benth (different parts), for example, are used to relieve toothache, severe stomachache, oedema associated with protein-calorie malnutrition disorders in infants when breast-feeding is terminated, pneumonia, and liver problems [52, 104, 105]. Such plants are used across different ethnic communities for managing malaria and can be a justification of their efficacy in malaria treatment [19].


### 3.6. Toxicity, Antiplasmodial, and Antimalarial Studies

Table3 shows the list of some of the antimalarial plants used in Kenya with reports of toxicity/safety, antimalarial, and antiplasmodial activity evaluation. Across African countries, many antimalarial plants captured in this review have demonstrated promising therapeutic potential on preclinical and clinical investigations [68, 106–111]. Interestingly, antimalarial compounds have been identified and isolated from some of these species [62, 112].Table 3
Antiplasmodial/antimalarial activities of investigated plants used for malaria treatment in Kenya and their active chemical constituents.
PlantPart usedExtracting solventAntiplasmodial (IC50 μg/ml)/antimalarial activity (Plasmodium strain)Active phytochemicals and toxicity informationReference (s)Justicia betonica L.ShootMethanol, water, ether69.6 (K39), >100 (K39), 13.36μg/mlJustetonin (indole(3,2-b) quinoline alkaloid glycoside)[117, 118]Allium sativum L.SyntheticEthanol50 mg/kg of ajoene suppressed development of parasitemia; ajoene (50 mg/kg) and chloroquine (4.5 mg/kg), given as a single dose, prevented development of parasitemiaAjoene, nontoxic[119]Acmella caulirhizaWhole plantDichloromethane9.939 (D6); 5.201 (W2)No reports[56]Aloe kedongensis ReynoldsLeavesMethanol87.7 (D6); 67.8 (W2)Anthrone, C-glucoside homonataloin, anthraquinones, aloin, lectins[120, 121]Aloe secundiflora Eng.Leaf exudateTested direct66.20 (K39)No reports[58]Achyranthes aspera L.Leaf, stem, roots, seedsEthanol>100, 76.75, >100, >100μg/mlAlkaloids, glycosides, saponins, triterpenoids[122]Artemisia annua L.LeavesWater1.1 (D10), 0.9 (W2)Sesquiterpenes and sesquiterpene lactones including artemisinin; safe and effective; artemisinin is safe for pregnant women[120, 123, 124]Bidens pilosa L.LeavesDichloromethane, chloroform, water, and methanol8.5, 5, 11, 70 (D10)No reports[76]Maytenus undata (Thunb.) BlakelockLeavesDichloromethane, dichloromethane/chloroform (1 : 1), methanol, water>100, 21, 60, >100 (D10)No reports[76]StemDichloromethane, dichloromethane/chloroform (1 : 1), methanol, water85, 24, 38, >100 (D10)RootsDichloromethane, chloroform, methanol, water23, 36, 40, >100 (D10)Rhus natalensis Bernh. ex KraussStem bark, leavesEthanol>50 (FcB1)Triterpenoids[50, 125]Leaves, rootsMethanol43.92 (D6), 51.2 (W2); >100 (D6), 80.44 (W2)Carissa edulis (Forssk.) VahlStem bark, root bark, rootsDichloromethane, chloroform, water, and methanol33 (D10), 6.41 (D6), >250, 148.53 and >250, >250 against ENT 30, and NF 54, respectivelyLignan, nortrachelogenin, cytotoxicity IC50 > 20, LD50 of 260.34, and 186.71 μg/ml for water and methanol extracts[48, 53, 76]Euphorbia tirucalli L.LeavesDichloromethane, dichloromethane/methanol (1 : 1), methanol, water12, 23.5, >100, 83 (D10)No reports[76]Psiadia punctulataTwigsDichloromethane, water9, >100 (D10)No reports[76]LeavesDichloromethane, dichloromethane/methanol (1 : 1), water14, 22.5, >100 (D10)Whole plantDichloromethane/methanol (1 : 1), water18 (D10), >100 (D10)Ricinus communis L.LeavesDichloromethane/methanol (1 : 1), water27.5, >100 (D10)No reports[76]StemsDichloromethane/methanol (1 : 1), water8, >100 (D10)FruitDichloromethane/methanol (1 : 1), water90, >100 (D10)Catharanthus roseus G. DonLeavesMethanol4.6 (D6); 5.3 (W2)Has neurotoxic alkaloids, terpenoids, flavonoids, sesquiterpenes[57, 126]Caesalpinia volkensii HarmsLeavesDecoction, ethanol, petroleum ether, methanol, water480, 481, 490, 858, 404 (FCA: 20 GHA), 923, 960, 250, 961, 563 (W2)No reports[11]Artemisia afra Jacq. ex WilldLeavesMethanol9.1 (, D6); 3.9 (W2)Acacetin, genkwanin, 7-methoxyacacetin; cytotoxicity observed in Vero cells[57, 127]Microglossa pyrifolia (Lam.) O. KtzeLeavesChloroform, dichloromethane<5 (both NF54 and FCR3)E-Phytol, 6e-geranylgeraniol-19-oic acid; cytotoxic to human foetal lung fibroblast cell lines[18, 25, 128, 129]Cucumis aculeatus CognFruitWater>30No reports[62]Schkuhria pinnata (Lam.)Whole plantWater22.5 (D6); 51.8 (W2)Schkuhrin I and schkuhrin II; methanol extract: low cytotoxicity against human cells; aqueous extracts: no toxicity observed in mice[57, 130]Solanecio mannii (Hook. f.) C. JeffreyLeavesMethanol21.6 (3D7); 26.2 (W2)Phytosterols,n-alkanes, and N-hexacosanol[120, 128]Tagetes minuta L.LeavesEthyl acetate61.0% inhibition at 10μg/mlNo reports[130]Tithonia diversifolia A. GrayLeaves, aerial partsMethanol, ether1.2 (3D7), 1.5 (W2), methanolic extract had 74% parasitemia suppressionTagitinin C and sesquiterpene lactones; aerial parts are cytotoxic against cells from the human foetal lung fibroblast cell line.[128, 131–133]Vernonia amygdalina Del.LeavesMethanol/dichloromethane, ethanol2.7 (K1), 9.83.In vivo parasite suppression of between 57.2 and 72.7% in combination with chloroquineVernolepin, vernolin, vernolide, vernodalin and hydroxy vernodalin, and steroid glucosides; petroleum ether extract shows strong cytotoxicity[111, 120, 130, 131, 134, 135]Vernonia auriculifera (Welw.) HiernLeavesEthane, chloroform, ethyl acetate, water>100, 37.7, 40.3, 55.2, >100 (K39)No reports[35]Vernonia brachycalyx O. Hoffm. SchreberLeavesChloroform/ethyl acetate, methanol6.6, 31.2 (K39) 29.6, 30.2 (V1/S)5-Methylcoumarin isomers, 16,17-dihydrobrachycalyxoloid[58]Vernonia lasiopus O. Hoffm.LeavesMethanol44.3 (D6); 52.4 (W2)Sesquiterpene lactones, polysaccharides[57, 120]Markhamia lutea (Benth.) K. Schum.LeavesEthyl acetate71% inhibition ofP. falciparum at 10 μg/mlPhenylpropanoid glycosides, cycloartane triterpenoids, musambins A-C, Candmusambiosides A-C[130, 136]Spathodea campanulataStem bark, leavesEthyl acetate, ethanol28.9% inhibition ofP. falciparumQuinone (lapachol)[130, 137, 138]Cassia didymobotrya Fres.LeavesMethanol23.4 (D6); undetectable (W2)Alkaloids[57]Warbugia ugandensis SpragueStem barkMethanol, water6.4 (D6); 6.9 (W2), 12.9 (D6); 15.6 (W2)Coloratane sesquiterpenes, e.g., muzigadiolide[57, 131, 139–141]Dichloromethane69% parasite inhibitionCarica papaya L.LeavesEthyl acetate2.96 (D10), 3.98 (DD2)Alkaloids, saponins, tannins, glycosides; no serious toxicity reported; carpaine, an active compound againstP. falciparum had high selectivity and was nontoxic to normal red blood cells[142, 143]Maytenus senegalensisRootsEthanol1.9 (D6), 2.4 (W2)Terpenoids, pentacyclic triterpenes, e.g., pristimerin; no toxicity observed in ethanol extract[144, 145]Ethulia scheffleri S.MooreLeavesChloroform/ethyl acetate/methanol49.8 (K39), 32.2 (V1/S)No reports[58]Combretum molle G. DonStem barkAcetone8.2 (3D7)Phenolics, punicalagin[146]Momordica foetida SchumachShootWater6.16 (NF54); 0.35 (FCR3)Saponins, alkaloid, and cardiac glycosides; no pronounced toxicity against human hepatocellular (HepG2) and human urinary bladder carcinoma (ECV-304, derivative of T-24) cells[25, 134, 147]Clutia abyssinica Jaub. & SpachLeavesMethanol7.8 (D6); 11.3 (W2)Diterpenes[57]Croton macrostachyus Olive.LeavesChloroform, dichloromethaneChemotherapeutic effect of 66–82%, 2 (D6)Triterpenoids including lupeol[14, 56]Flueggea virosa (Roxb. ex Willd) VoigtLeavesWater/methanol2.0 (W2)Bergenin, nontoxic, extracts exposed to murine macrophages did not slow or inhibit growth of cells[148, 149]Erythrina abyssinica Lam.Stem barkEthyl acetate83.6% inhibition ofP. falciparum at 10 μg/mlChalcones (5-prenylbutein and homobutein), flavanones including 5-deoxyabyssinin II, abyssinin III, and abyssinone IV[130, 137]Kigelia africana (Lam.) BenthBark, fruitChloroform/ethyl acetate, methanol59.9 (K39), 83.8 (V1/S); fruits had 165.9 (K39)No reports[58]Trichilia emetica VahlLeaves, twigsDichloromethane/methanol (1 : 1)3.5 for all (D10)Kurubasch aldehyde[76, 150]Senna didymobotrya (Fresen.) H. S. Irwin & BarnebyLeaves, twigsMethanol, dichloromethane/methanol (1 : 1)>100 (K39), 9.5 (D10)Quinones[35, 76, 117]Tamarindus indica L.Stem barkWater25.1% chemosuppressive activity at 10 mg/kg (P. berghei)Saponins (leaves), tannins (fruits)[73]Harungana madagascariensis Lam.Stem barkWater, ethanol9.64 (K1); <0.5 with 28.6–44.8% parasite suppressionQuinones including bazouanthrone, ferutinin A, harunganin, harunganol A, anthraquinones, saponins, steroids[137, 151–153]Rotheca myricoides (Hochst.) Steane and MabbLeavesMethanol9.51–10.56 and 82% parasite suppression at 600 mg/kgNo reports[154]Leucas calostachys Oliv.LeavesMethanol3.45 with parasite inhibition of 3.5–5.2%No reports[82]Ajuga remota Benth.Whole plantEthanol; decoction, ethanol, petroleum ether, methanol, and water55 (FCA/GHA), 57 (W2); 937, 55, 149, 504, 414 (FCA/GHA), 371, 57, 253, 493, 101 (W2)Ajugarin-1, ergosterol-5,8-endoperoxide, 8-oacetylharpagide, steroids[11, 14]Suregada zanzibariensis BaillRoot barkWater, methanol≤10 (K67), (ENT36)Alkaloids[96, 155]Clerodendrum myricoides R. Br.Root barkEthanol4.7 (D6); 8.3 (W2)No reports[156, 157]Chloroform>10 (D6)Cytotoxicity, IC50 > 20.0 μg/ml[48]Hoslundia opposita Vahl.LeavesEthyl acetate66.2% inhibition ofP. falciparum at 10 μg/mlQuinones, saponins, abietane diterpenes (3-obenzoylhosloppone)[50, 130]Roots; aerial partsMethanol79.38 (D6), 64.21 (W2); 19.73 (D6), 29.41 (W2)Leonotis nepetifoliaLeavesEthyl acetate, dichloromethane/methanol (1 : 1), water27.0% inhibition ofP. falciparum at 10 μg/ml, 15, >100 (D10)No reports[76, 130]Ocimum basilicum L.Leaves, whole plantEthanol68.14 (3D7); 67.27 (INDO)No reports[156, 157]Ocimum gratissimum WildLeaves/twigsDichloromethane8.6 (W2)Flavonoids[56, 158]Ocimum suave WildLeavesWater (hot), chloroform/methanol mixture100 mg/kg/day of extracts provided 81.45% and 78.39% parasite chemosuppression[71]Plectranthus barbatus AndrewsLeavesDichloromethaneNo activityNo toxicity recorded[56, 71]Root barkWater (hot), chloroform/methanol mixture100 mg/kg/day of extracts had 55.23% and 78.69% parasite chemosuppressionAzadirachta indica A. Juss.LeavesWater, methanol17.9 (D6); 43.7 (W2)Terpenoids, isoprenoids, gedunin, limonoids: khayanthone, meldenin, and nimbinin; cytotoxicity LD50 of 101.26 and 61.43 μg/ml for water and methanol extracts[53, 144, 158–160]Melia azedarachLeavesMethanol, dichloromethane55.1 (3D7), 19.1 (W2); 28No reports[161, 162]Ficus thonningii BlumeLeavesHexane10.4No reports[163]Cissampelos mucronata A. Rich.Root bark, rootMethanol, ethyl acetate8.8 (D6); 9.2 (W2); root extract <3.91 (D6), 0.24 (W2) for the active compound (curine)Benzylisoquinoline alkaloids, curine[74, 75, 157]Acacia nilotica L.Stem barkMethanol100 mg/kg produced 77.7% parasitic inhibitionTannins, flavonoids, terpenes[53, 164]Water, methanol>250, 153.79 (ENT 30), 73.59, 70.33 (NF 54)LD50 of 368.11 and 267.31 μg/ml for water and methanol extractsAlbizia coriaria Welw. ex OlivStem barkMethanol15.2 (D6); 16.8 (W2)Triterpenoids, lupeol, lupenone[57]Ageratum conyzoides L.Whole plantDichloromethane, methanol2.15 (D6); 3.444 (W2), 11.5 (D6); 12.1 (W2)Flavonoids[57]Albizia zygia (DC.) Macbr.Stem barkMethanol1.0 (K1)Flavonoids mainly 3′,4′,7-trihydroxyflavone; aqueous extract is relatively safe on subacute exposure[165, 166]Maesa lanceolata Forsk.TwigDichloromethane: methanol (1 : 1)5.9 (D10)Lanciaquinones, 2,5, dihydroxy-3-(nonadec-14-enyl)-1,4-benzoquinone[76, 128, 167]Securidaca longipedunculata Fresen.LeavesDichloromethane6.9 (D10)Saponins, flavonoids, alkaloids, steroids[168]Prunus africana (Hook. f.) KalkmanStem barkMethanol17.3 (D6); not detected (W2)Terpenoids[57]Pentas longiflora Oliv.RootMethanol0.99 (D6); 0.93 (W2)Pyranonaphthoquinones, pentalongin and psychorubrin, and naphthalene derivative mollugin; low cytotoxicity[169]Teclea nobilis DelileBark70% ethanol53.27% suppression of parasitemia at 700 mg/kgTannins, alkaloids, saponins, flavonoids[167, 170]Ethyl acetate54.7% inhibition ofP. falciparum at 10 μg/mlQuinoline alkaloids[130]Toddalia asiaticaRoot bark, fruits, and leavesMethanol, water, ethyl acetate, hexane6.8 (D6); 13.9 (W2); ethyl acetate fruit extract (1.80 mg/ml), root bark aqueous (2.43) (W2)Furoquinolines (nitidine and 5,6-dihydronitidine), coumarins; acute and cytotoxicity of the extracts, with the exception of hexane extract from the roots showed LD50 > 1000 mg/kg and CC50 > 100 mg/ml, respectively[84, 157]Zanthoxylum chalybeum Engl.Stem barkWater4.3 (NF54); 25.1 (FCR3)Chelerythine, nitidine, and methyl canadine; no toxicity recorded[25, 71]Trimeria grandifolia (Hochst.) Warb.LeavesMethanol>50 (3D7)No reports[128]Harrisonia abyssinica Olive.RootsWater, methanol4.4 (D6), 10.25 (W2); 89.74, 79.50 (ENT 30); 86.56, 72.66 (NF 54)Limonoids and steroids; LD50 of 234.71 and 217.34 μg/ml for water and methanol extracts[53, 144]Lantana camara L.Leaves, leaves/twigsDichloromethane, dichloromethane/methanol (1 : 1), water8.7 (3D7), 5.7 (W2), 11 (D10), >100 (D10), >100 (D10)Lantanine, sesquiterpenes, triterpenes, flavonoids[76, 171]Flacourtia indica (Burm. f.) Merr.RootsDichloromethane, dichloromethane/methanol (1 : 1), water86.5 (D10), 78 (D10), >100 (D10)No reports[76]Clausena anisataTwigs, leavesDichloromethane/methanol (1 : 1), water18 (D10), >100 (D10); 55, >100 (D10)No reports[76]Flueggea virosa (Roxb.ex Willd.) Baill.Leaves/twigsDichloromethane/methanol (1 : 1), water19 (D10), 11.4 (D10)Alkaloids: Securinine and viroallosecurinine had IC50 of 2.7 and 2.9Alkaloids, bergenin (root bark), securinine, and viroallosecurinine[76, 172–174]Lantana trifolia L.Ariel partsPetroleum ether, chloroform, ethanol13.2, >50, >50 (plasmodial lactate dehydrogenase)Steroids, terpenoids, alkaloids, saponins[125]Bridelia micrantha (Hochst.) Baill.Stem bark, leavesMethanol158.7 (K1)No reports[175]Balanites aegyptiaca (L.) Del.Root barkChloroform3.49 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Sericocomopsis hildebrandtiiRoot barkChloroform3.78 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Boscia angustifoliaInner barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Acacia tortilisRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Commiphora schimperiInner barkChloroform4.63 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Acacia melliferaInner barkChloroform4.48 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Fuerstia africanaLeaf, aerial parts, leavesChloroform, petroleum ether, methanol3.76 (D6), 1.5, <15 with >70% parasite suppressionFerruginol, cytotoxicity IC50 > 20 μg/ml[48, 65, 131, 176]Psiadia punctulataRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Ajuga integrifolia Buch.-HamLeavesMethanol35.17% at 800 mg/kg/day parasite suppressionAlkaloids, flavonoids, saponins, terpenoids, anthraquinone, steroids, tannins, phenols, and fatty acids; no lethal effect on mice in 24 h and within 10 days of observation[177]Albizia gummiferaMethanol0.16 (NF54), 0.99 (ENT 30) for alkaloidal fraction, spermine alkaloids had parasite suppression of 43–72%Spermine alkaloids (budmunchiamine K, 6-hydroxybudmunchiamine K, 5-normethylbudmunchiamine K, 6-hydroxy-5-normethylbudmunchiamine K, 9-normethylbudmunchiamine K)[178]Rhamnus staddoRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Ocimum kilimandscharicumLeaves, twigsDichloromethane0.843 (D6); 1.547 (W2)No reports[56]Gutenbergia cordifoliaLeavesChloroform0.4 (D6)Cytotoxicity IC50 = 0.2 μg/ml[48]Piper capenseRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Pentas lanceolataRoot barkChloroform5.15 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Clematis brachiataRoot barkChloroform4.15 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Ekebergia capensisInner bark, fruit, twigsChloroform, dichloromethane/methanol (1 : 1)3.97 (D6), 10, 18 (D10)Cytotoxicity IC50 > 20 μg/ml[48, 76]Rhamnus prinoidesRoot barkChloroform3.53 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Olea europaea ssp. AfricanaInner bark, leaves, twigsChloroform, dichloromethane/methanol (1 : 1)9.48 (D6), 12, 13 (D10)Cytotoxicity IC50 > 20 μg/ml[48, 76]Pappea capensisInner barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Pittosporum viridiflorum SimsWhole plant, leaves/flowersDichloromethane, methanol, dichloromethane/methanol (1 : 1)3, 10, 27.7, (D10), 28, 47, 70.5 (D10)Triterpenoid estersaponin, pittoviridoside (saponins)[76, 179, 180]Podocarpus latifoliusRoot barkChloroform6.43 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Rumex abyssinicus Jacq.RootDichloromethane<15No reports[176]Rubus pinnatus WildLeavesEthanol20% parasite suppressionNo reports[130]Zanthoxylum gilletiiStem barkDichloromethane/methanol (1 : 1)2.52 (W2), 1.48 (D6), 1.43 (3D7)Nitidine, seas amine 8-acetyl dihydrochelerythrine[86, 176]Solanum incanum L.LeavesChloroform/methanol31% parasite suppressionNo reports[87]Rhoicissus tridentataRootsWater>40.0No reports[62]Acacia hockiiRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Lippia javanica (Burm.f.) SprengRootsChloroform/ethyl acetate, methanol16.7, 40.6 (K39), 19.2, 40.1 (V1/S)No reports[58, 76]Roots, stemDichloromethane, methanol, dichloromethane/methanol (1 : 1)3.8, 27, 24 (D10), 4.5, 21.8, 29.8 (D10)Premna chrysoclada (Bojer) GürkeRoots, leavesMethanol27.63 (D6), 52.35 (W2); 7.75 (D6), 9.02 (W2)Not cytotoxic at 100μg/ml[50]Allophylus pervillei BlumeRoots, stem barkMethanol45.62 (D6), 48.91 (W2); >100 (D6),>100 (W2)Not cytotoxic at 100μg/ml[50]Aganthesanthemum bojeri Klotzsch.Whole plantMethanol55.3 (D6), 55.97 (W2)Not cytotoxic at 100μg/ml[50]Abrus precatorius L.LeavesMethanol85.59 (D6), >100 (W2)Not cytotoxic at 100μg/ml[50]Combretum illairii Engl.Stem bark, leavesMethanol55.96 (D6), 58.54 (W2); 24.21 (D6), 33.31 (W2)Not cytotoxic at 100μg/ml[50]Grewia plagiophylla K. SchumLeaves, stem barkMethanol13.28 (D6), 34.2 (W2); >100 (D6), >100 (W2)Not cytotoxic at 100μg/ml[50]Combretum padoides Engl. & DielsRootsMethanol21.73 (D6), 59.43 (W2)Not cytotoxic at 100μg/ml[50]Uvaria acuminataLeaves, rootsMethanol51.13 (D6), >100 (W2); 8.89 (D6), 6.90 (W2)Cytotoxic with CC50 of 2.37 μg/ml.[50]Ormocarpum trachycarpumRootsChloroform/ethyl acetate, methanol, water19.6, 41.7, 79.4 (K39); 17.5, 32.8 (V1/S)No reports[58]Plectranthus sylvestris GurkeLeavesChloroform/ethyl acetate, methanol41.1, 56.2 (K39); 61.0 (V1/S)No reports[58]Turraea robustaRoot barkWater, methanol25.32, 2.09 (D6), 42.41, 10.32 (W2)IC50 of 24.38 and 45.72 μg/ml for methanol and aqueous extracts against Vero cells (cytotoxic)[49]Lannea schweinfurthiiStem barkWater, methanol10.55 and 75.90, 11.38 and 36.26 (D6 and W2)IC50 of 225.25 and 3256.52 μg/ml for methanol and aqueous extracts against Vero cells[49]Sclerocarya birreaStem barkWater, methanol18.96 and 71.74, 5.91 and 24.96 (D6 and W2)IC50 of 361.24 and 3375.22 μg/ml for methanol and aqueous extracts against Vero cells[49]Withania somniferaStem barkWater, methanol>250, >250 (ENT 30); 145.86, 125.59 (NF 54)LD50 of 301.44 and 207.27 μg/ml for water and methanol extracts[53]Zanthoxylum usambarenseStem barkWater, methanol14.33, 5.25 (ENT 30); 5.54, 3.20 (NF 54)LD50 of 260.90 and 97.66 μg/ml for water and methanol extracts[53]Fagaropsis angolensisStem barkWater, methanol10.65, 6.13 (ENT 30); 5.04, 4.68 (NF 54)LD50 of 173.48 and 57.09 μg/ml for water and methanol extracts[53]Myrica salicifoliaStem barkWater, methanol85.97, 66.84 (ENT 30); 55.89, 51.07 (NF 54)LD50 of 328.22 and 320.17 μg/ml for water and methanol extracts[53]Strychnos henningsii GilgStem barkWater, methanol73.39, 67.16 (ENT 30); 190.0, 159.71 (NF 54)LD50 of 293.93 and 101.22 μg/ml for water and methanol extracts[53]Neoboutonia macrocalyxStem barkWater, methanol92.85, 84.56 (ENT 30); 78.44, 78.40 (NF 54)LD50 of 41.69 and 21.04 μg/ml for water and methanol extracts[53]Urtica massaica Mildbr.Aerial partsHexane, chloroform, ethyl acetate, water, methanol>100 (K39)No reports[35]Uvaria scheffleri DielsLeaves, stem, root barkPetroleum ether, dichloromethane, methanol5–500 (K1)Indole alkaloid-(±L)-schefflone, uvaretin, diuvaretin[181, 182]Rauwolfia cothenRoot barkPetroleum ether, dichloromethane, methanol0–499 (K1)Yohimbine, an indole alkaloid[183, 184]Tridax procumbens L.Whole plantDichloromethane/methanol (1 : 1), water17 (D10), >100 (D10)Bergenin[76, 184, 185]Centella asiaticaLeavesDichloromethane/methanol (1 : 1)8.3 (D10)Alkaloids, sesquiterpenes[76, 186]Ficus surStem barkHexane, chloroform, ethyl acetate, water, methanol19.2, 9.0, >100, >100, >100 (K39)No reports[35]Euphorbia inaequilatera Sond.Whole plantHexane, chloroform, ethyl acetate, water, methanol19.2, 9.0, >100, >100, >100 (K39)No reports[35]Spermacoce princeae (K. Schum.) Verdc.Whole plantHexane, chloroform, ethyl acetate, water, methanol>100 (K39)No reports[35]Senna occidentalisLeavesDimethyl sulfoxide, ethanol48.80 (3D7), 54.28 (NIDO); <3;Quinones[156, 187, 188]Ethanol, dichloromethane>60% parasitemia suppressionSearsia natalensis (Bernh. ex C. Krauss)LeavesChloroform1.8 (plasmodial lactate dehydrogenase)No reports[125]Plasmodium falciparum isolates: D6, 3D7, D10, FCA/GHA (FCA: 20 GHA), FCR3, K39, and NF54 are chloroquine sensitive; DD2, ENT 30, FCR3, K1, NIDO, V1/S, and W2 are chloroquine resistant. For [48], control used for cytotoxicity study (vinblastine) had the effective dose to inhibit 50% growth (ED50) = 0.038 μg/ml. An ED50 greater than 20 μg/ml indicates that the plant extract lacks cytotoxicity. The control drug chloroquine had a toxicity of 17.4 μg/ml and IC50 of 0.004 μg/ml against D6 clone.Export of indigenous medicinal plants bring substantial foreign exchange to African countries such as Egypt [113], South Africa [114], Uganda, Tanzania, and Kenya [115]. Despite the success of traditional practices and abundance of indigenous medicinal plants (Table 1), antimalarial plants research in Kenya stops mostly on ethnobotanical surveys, with extensions limited to evaluation of crude extracts from plants against Plasmodium berghei [48, 56, 71]. A gap is evident with regard to research geared towards identifying and isolating plant bioactive compounds and establishing the efficacy and safety of medicinal plants through in vitro assays using human Plasmodium parasites and in vivo assay involving higher animal models and randomized clinical trials [50]. For example, the toxicity of 16,17-dihydrobrachycalyxolid isolated in Vernonia brachycalyx has been reported to be due to its ability to inhibit the proliferation of phytohaemmaglutinin-treated human lymphocytes [116]. A median inhibitory concentration (IC50) of 7.8 μg/ml was reported, which is comparable to the median concentration obtained in the antiplasmodial assay by Oketch-Rabah et al. [58] (Table 3). To assess whether observed antiplasmodial activities are due to a specific or a general toxicity effect, the experimental selectivity index (SI) needs to be calculated for extracts and only a few studies in Kenya has attempted this [48–50]. It is worth noting that there is always a variation in the degree of toxicity depending on the sensitivity of the animals, tissue, or cells used, type of extract, nature of the test substance, dose, and mode of administration. In this study, 38.8% (54/139) of the total plants were evaluated for their toxicities. Of these, 41 showed low cytotoxicity with LC50 > 20 μg/ml. Some of these plants such as Artemisia annua, Carica papaya, Flueggea virosa, and Schkuhria pinnata fortuitously showed good antimalarial activity. On the contrary, extracts of some plants used for malaria treatment with good activity are potentially toxic, for example, dichloromethane leaf extract of Microglossa pyrifolia, methanolic extract of Uvaria acuminata (CC50 = 2.37 μg/ml), and petroleum ether leaf extract of Vernonia amygdalina.In total, 139 (48.6%) of the species identified have been investigated for antiplasmodial (n = 25, 18%) or antimalarial activities (n = 135, 97.1%). However, there is no record on antiplasmodial or antimalarial activity of about 51.4% of the species used although they could be potential sources of antimalarial remedies. In the antiplasmodial activity, parasite suppression ranged from 3.5 to 5.2% in Leucas calostachys Olive aqueous leaf extracts [82] to 90% in Ajuga integrifolia aqueous leaf extracts [177]. In antimalarial studies against chloroquine-sensitive (D6, 3D7, D10, FCA/GHA, FCR3, K39, and NF54) and chloroquine-resistant (DD2, ENT 30, FCR3, K1, V1/S, and W2) P. falciparum isolates, 49.6% (67/135) were active with the lowest IC50 of 0.16 μg/ml recorded against NF54 isolate for spermine alkaloids in Albizia gummifera [178]. On the other hand, 68 species (50.4%) were inactive. The most active extracts were those of isolated pure compounds. For example, spermine alkaloids: budmunchiamine K, 6-hydroxybudmunchiamine K, 5-normethylbudmunchiamine K, 6-hydroxy-5-normethylbudmunchiamine K, and 9-normethylbudmunchiamine K from Albizia gummifera bark [178] had IC50 of 0.16 μg/ml recorded against ENT30. Curine, isolated from Cissampelos mucronate roots, showed antimalarial activity against W2 isolate with IC50 of 0.24 μg/ml [74]. At present, Artemisia annua [106, 107], Azadirachta indica [108], and Vernonia amygdalina [111] have been subjected to clinical studies. Artemisinin from Artemisia annua is an ingredient of artemisinin-based combination therapy currently recommended for treatment of malaria [124]. As identified earlier, few clinical trials have been done on antimalarial plants. This is partly due to the regulatory requirements for clinical studies, as well as the financial input required.


## 3.1. Antimalarial Plants Used in Kenya

In aggregate, 61 studies and reports identified 286 plant species from different regions of Kenya belonging to 75 botanical families distributed among 192 genera (Table1). Asteraceae (36.5%), Fabaceae (29.7%), Lamiaceae (24.3%), Euphorbiaceae (21.6%), Rutaceae (17.6%), and Rubiaceae (17.6%) were the most common plant families (Figure 1). The most frequently encountered species were Toddalia asiatica (L.) Lam (11 times), Aloe secundiflora Engl. (10 times), Azadirachta indica A. Juss, Carissa edulis (Forsk.) Vahl., Harrisonia abyssinica Olive (9 times each), Zanthoxylum chalybeum Engl. (8 times), Ajuga remota Benth., Rotheca myricoides (Hochst.) Steane and Mabb, Warburgia ugandensis Sprague (7 times each), Albizia gummifera (J. F. Gmel.), Erythrina abyssinica Lam. ex DC., Plectranthus barbatus Andrews, Rhamnus prinoides L.’Herit, Senna didymobotrya (Fresen) Irwin and Barneby, and Solanum incanum L. (6 times). One botanically unidentified plant (Ima) was reported by Kuria et al. [11]. Decoction of a whole lichenized fungi (Usnea species and Intanasoito in Maasai dialect) and Engleromyces goetzei P. Henn. fungi were also reported to be used in management of malaria in rural Kenya [22, 23].Table 1
Synopsis of medicinal plants used in the management of malaria in Kenya.
Plant familyBotanical nameLocal namePart(s) usedHabitPreparation modeReference(s)AcanthaceaeJusticia betonica L.ShikuduliAerial partsHerbDecoction[34, 35]AlliaceaeAllium sativum L.Kitungu saumu (Luo)RootsHerbCrushed, chewed[36]AloeaceaeAloe barbadensis Mill. (vera)Oldopai (Maasai)LeavesHerbNot specified[37]Aloe kedongensis ReynoldsOsukuroi (Maasai)Leaves, rootsHerbInfusion[3, 38–40]Aloe elgonica BullockNot reportedLeaves, rootsHerbDecoction[41]Aloe lateritia Engl.Kiiruma (Kikuyu)Leaves, rootHerbDecoction[3, 42]Aloe volkensii Engl.Osukuroi (Maasai)LeavesHerbDecoction[22]Caesalpinia volkensii HarmsMujuthi (Kikuyu)LeavesLianaDecoction[3, 11, 43, 44]AmaranthaceaeAchyranthes aspera L.Uthekethe (Kamba)Whole plantHerbNot specified[23, 45]Amaranthus hybridus L.Mchicha (Swahili)LeavesHerbDecoction[17, 46]Celosia schweinfurthiana Schinz.Not reportedNot specifiedShrubNot specified[47]Cyathula schimperiana non MoqNamgwetLeaves, rootsHerbDecoction[38, 40]Cyathula cylindrica MoqNg’atumyatRootsHerbDecoction[38, 40]Sericocomopsis hildebrandtii Schinz.Oloituruj-ilpeles (Maasai)RootsShrubDecoction[22, 48]AnacardiaceaeHeeria insignis Del.Mwamadzi (Swahili)Bark, stem barkTreeDecoction[17, 46]Lannea schweinfurthii (Engl.) Engl.MnyumbuBark, leavesShrubNot specified[49, 50]Ozoroa insignis DelileNot reportedNot reportedShrubNot specified[42]Rhus natalensis Bernh. ex KraussMuthigiu (Kikuyu)Root, stem, fruits, root barkTreeDecoction[3, 42, 49–51]Rhus vulgaris MeikleSungulaLeavesHerbDecoction[3, 42]Sclerocarya birrea (A. Rixh.) HochstOloisuki (Maasai)BarkTreeNot specified[49]Searsia natalensis (Bernh. ex C. Krauss)Olmisigiyioi (Maasai)LeavesHerbDecoction[34]AnnonaceaeUvaria acuminata Oliv.Mukukuma (Kamba)RootsShrubNot specified[50]Uvaria scheffleri DielsNot reportedLeavesLianaDecoction[17]ApiaceaeCentella asiatica (L.) Urb.Not reportedLeavesHerbDecoction[17]ApocynaceaeCarissa edulis (Forssk.) Vahl.Olamuriaki (Maasai), Mukawa (Kikuyu)Root, root barkShrubDecoction, inhale steam[3, 17, 34, 38, 40, 47, 48, 52, 53]Catharanthus roseus (L.) G. DonOlubinuNot specifiedHerbNot specified[47]Gomphocarpus fruticosus (L.) W. T. AitonKosirichRootHerbNot specified[54]Laudolphia buchananii (Hall.f) StapfMhonga (Swahili)LeavesLianaDecoction[17, 46]Mondia whiteiOgombo (Luo)RootsHerbChewed[42]Rauwolfia cothenNot reportedRoot barkShrubDecoction[17]Saba comorensis (Bojer ex A.D.C) PichonAbuno (Luo)Not specifiedHerbNot reported[42]AsclepiadaceaeCurroria volubilis (Schltr.) BullockSimatwetBarkLianaDecoction[38, 40]Periploca linearifolia Dill. & A. Rich.Muimbathunu (Kikuyu)BarkLianaDecoction[3, 44]AsteraceaeAchyrothalamus marginatus O. Hoffm.Not reportedLeavesHerbDecoction[55]Acmella caulirhiza Del.ShitutiAerial partsShrubDecoction[34, 56]Ageratum conyzoides L.Not reportedWhole plantHerbDecoction[56, 57]Artemisia afra JacqNot reportedLeavesShrubDecoction[41]Artemisia annua L.Not reportedLeavesShrubDecoction[42]Aspilia pluriseta Schweinf.RirangeraLeavesHerbDecoction[35]Bidens pilosa L.Nyanyiek mon (Luo)LeavesHerbDecoction[11, 37]Ethulia scheffleri S. MooreNot reportedLeavesHerbDecoction[58]Gutenbergia cordifolia Benth.Olmiakaru-kewon (Maasai)LeavesHerbDecoction[48]Kleinia squarrosaMungendya (Kamba)LeavesShrubInfusion[55]Launaea cornuta (Oliv and Hiern) C. JeffreyUthunga (Kamba)LeavesLianaInfusion/decoction[17, 46, 55]Microglossa pyrifolia (Lam.) O. KuntzeNyabung-Odide (Luo)Root, leavesShrubDecoction[34, 37, 38]Psiadia arabica Jaub. & PachNyabende winy (Luo)Not specifiedHerbNot specified[42]Psiadia punctulata (D.C.) VatkeOlobai (Maasai)RootsHerbNot specified[48]Sonchus schweinfurthii Oliv. & HiernEgesemi (Kuria)Not specifiedHerbNot specified[37]Schkuhria pinnata (Lam.) Kuntze ex ThellGakuinini (Kikuyu)Whole plantHerbInfusion[3, 23, 42, 44]Senecio syringitolia O. HoffmanReisa (Digo)LeavesHerbDecoction[17, 46]Solanecio mannii (Hook. f) C. JeffreyMaroo, marowo (Luo), LivokhoLeavesShrubDecoction[23]Sonchus luxurians (R.E. Fries) C. JeffreyKimogit (Nandi)RootsHerbDecoction[38]Sphaeranthus suaveolens (Forsk.) DCNjogu-ya-iriaWhole plantHerbInfusion, rubbed on the body[44, 52]Tithonia diversifolia (Hemsl.) GrayMaua madongo (Luo)LeavesShrubDecoction[3, 34, 42]Tridax procumbens L.Not reportedWhole plantHerbInfusion[17]Vernonia amygdalina Del.MusulilitsaLeavesShrubDecoction[17, 34, 42]Vernonia auriculifera (Welw.) HiernMuthakwaLeaves, roots, barkShrubInfusion, decoction[35, 37, 38, 41, 44]Vernonia brachycalyx O. Hoffm. SchreberIrisabakw (Kuria)LeavesHerbDecoction[37, 44, 58]Vernonia brachycalyx O. Hoffm. Lasiopa Lam.Olusia (Luo)LeavesHerbDecoction[37]Vernonia lasiopus O. Hoffm.Shiroho, MwathaLeaves, root barkShrubInfusion[23, 35, 44]BignoniaceaeKigelia africana (Lamk.) Benth.Omurabe, MorabeLeaves, bark, fruitsTreeDecoction[44, 58, 59]Markhamia lutea (Benth.) K. Schum.Lusiola, ShisimbaliBarkTreeDecoction[34, 47]Markhamia platycalyx SpragueSiala (Luo)Not specifiedTreeNot specified[42]Spathodea campanulata P. Beauv.Muthulio, MutsuriaLeavesTreeDecoction[34]BoraginaceaeEhretia cymosa ThonnMororwetLeaves, rootsShrubInfusion[38, 40]BurseraceaeCommiphora eminii EnglMukungugu (Kikuyu)Not specifiedTreeNot specified[3]Commiphora schimperi (Berg) Engl.Osilalei (Maasai), Dzongodzongo (Swahili)Inner bark, roots, stem barkTreeDecoction[17, 46, 48]CanellaceaeWarburgia salutaris (Bertol.F.) Chiov.Osokonoi (Maasai)BarkTreeDecoction[22, 37, 45]Warburgia stuhlmannii Engl.Not reportedStem barkTreeDecoction[17]Warburgia ugandensis Sprague subsp ugandensisMuthiga (Kikuyu)Stem bark, fruits, leavesTreeDecoction[3, 11, 22, 34, 43, 51, 54]CapparaceaeBoscia angustifolia A. Rich.Oloiroroi (Maasai)Inner bark fibres, stem barkTreeDecoction[42, 44, 48, 52]Boscia salicifolia Oliv.Mwenzenze (Kamba)Not specifiedTreeNot specified[49]Cadaba farinosa ForsskAkado marateng (Luo)Not specifiedShrubNot specified[42]CapparidaceaeCleome gynandra L.IsakiatLeaves, rootsHerbDecoction[40]CariaceaeCarica papaya L.Poipoi, Apoi (Luo)Leaves, roots, sapShrubInfusion, decoction[36]CelastraceaeMaytenus arbutifolia (A. Rich.) WilczekMuragaRoot barkShrubDecoction[44]Maytenus heterophylla (Eckl. & Zeyh.) N. RobsonMuragaRoot, root barkShrubDecoction[41, 44]Maytenus putterlickioides (Loes.) Excell & MendoncaMuthuthiRoot barkShrubDecoction[44]Maytenus senegalensis (Lam.) ExellMuthuthi (Kikuyu)Not specifiedShrubNot specified[3, 47]Maytenus undata (Thunb.) BlakelockMuthithioiRoot bark, leavesShrubDecoction[44]CleomaceaeCleome gynandra L.IsakiatLeaves rootsHerbDecoction[38]CombretaceaeCombretum illairii Engl.Mshinda arumeLeaves, root barkTreeDecoction[50]Combretum molle G. DonMuama, Kiama (Kamba)Bark, leavesTreeDecoction[17, 45]Combretum padoides Engl. & DielsMshinda arumeLeaves, rootsTreeDecoction[17, 46, 50, 60]Terminalia brownii Fresen.Muuku (Kamba)BarkTreeDecoction[55]Terminalia spinosa Engl.Not reportedBark, stem barkTreeDecoction, infusion[17, 61]CommelinaceaeAneilema spekei (C. B. Clarke)Enkaiteteyiai (Maasai)Whole plantLianaDecoction[22]Commelina forskaolii VahNot reportedNot specifiedHerbNot specified[47]CrassulaceaeKalanchoe lanceolata (Forsk.) Pers.Mahuithia (Kikuyu)Not specifiedHerbNot specified[3]CucurbitaceaeCucumis aculeatus Cogn.Gakungui (Kikuyu)LeavesClimberDecoction[3, 34, 42, 62]Cucumis prophetarum L.Chepsawoy (Kipsigis)Root tuberHerbDecoction[39]Gerranthus lobatus (Cogn.) JeffreyMgore manga (Digo)Leaves, rootsHerbDecoction[17, 46]Momordica foetida SchumachCheptenderet (Kipsigis)Leaves, rootsLianaDecoction, roasting[17, 38, 41]Momordica friesiorum Hams C. JeffreyLibobolaRoot tuberHerbDecoction[54]Zehneria minutiflora (Cogn.) C. JeffreyManereriat (Kimanererit)Leaves, rootsLianaDecoction[38]CyperaceaeCyperus articulatus L.NdagoTuberHerbInfusion[44]EbenaceaeEuclea divinorum HiernUswet (Markweta)Root barkTreeDecoction, use for brushing teeth[38, 47]Diospyros abyssinica (Hiern) F. White subsp. abyssinicaLusuiBarkTreeDecoction[41, 59]Diospyros scabraNot reportedBarkTreeDecoction[61]EuphorbiaceaeBridelia micrantha Baill. (Hochst).Mdungu (Digo)Leaves, bark, stem barkShrubDecoction[17, 46]Clutia abyssinica Jaub. & SpachMuthima mburi (Kikuyu)Leaves, root, root barkShrubDecoction[3, 38, 44]Croton dichogamus Pax.Oloiborrbenek (Maasai)Whole plantShrubDecoction[22, 38]Croton macrostachyus Hochst. ex Del.Mukinduri (Kikuyu)Leaves, root, barkTreeDecoction[34, 38, 56]Croton megalocarpoides Friis & M.G. GilbertOrmegweit (Maasai)BarkTreeDecoction[22]Croton megalocarpus Del.Not reportedNot specifiedTreeNot specified[3]Euphorbia inaequilatera Sond.Ogota KwembebaWhole plantShrubDecoction[35]Euphorbia meridionalis Bally & S. CarterEnkokuruoi (Maasai)StemClimberNot specified[22]Euphorbia tirucalli L.Kariria (Kikuyu)Not specifiedTreeNot specified[3]Flueggea virosa (Willd.) VoigtMukwambaRoot barkTreeDecoction[50]Flueggea virosa (Roxb.ex Willd.) RoyleMkwamba, mteja (Swahili)Aerial parts, root barkShrubDecoction[17, 34]Neoboutonia macrocalyx PaxMutuntukiLeaves, stem barkTreeDecoction[44, 53]Phyllanthus sepialis Müll. Arg.Not reportedLeavesShrubDecoction[34]Ricinus communis L.Kivaiki (Kamba)Root, seeds, leavesShrubDecoction, topical[17, 38, 46]Sapium ellipticumAchak (Luo)Not specifiedShrubNot specified[42]Suregada zanzibariensis BaillNot reportedRoot barkShrubDecoction[17]FabaceaeAbrus precatorius L. ssp africanus VerdcNdirakaluLeavesHerbNot specified[42, 50]Acacia hockii De Wild.Eluai (Maasai)Root barkTreeDecoction[48]Acacia mellifera (M.Vahl) Benth.Oiti (Maasai), Muthiia (Kamba)Stem bark, root, pithTreeDecoction[11, 22, 48, 52, 63]Acacia nilotica (L.) Willd.ex DelileOlkirorit, Ol-rai (Masaai)Bark, rootTreeDecoction[22, 37, 53, 64]Acacia oerfota (Forssk.) Schweinf.Not reportedRootTreeNot reported[63]Acacia seyal DelileMgunga (Digo)RootTreeDecoction[17]Acacia tortilis (Forssk.) HayneOltepesi (Maasai)Sap, rootsTreeTaken directly, decoction[22, 48]Albizia amara (Roxb.) Boiv.MwiradathiStem barkTreeDecoction[44]Albizia anthelmintica Brongn.Kyoa (Kamba)Root, barkTreeDecoction[17, 22, 63]Albizia coriaria Welw ex OliverOmubeliMultiple partsTreeDecoction[42, 47, 57, 65]Albizia gummifera (J.F. Gmel.)Seet (Nandi)Root, stem barkTreeDecoction[23, 34, 38, 42, 44, 66]Albizia zygia (DC) J.F. Macbr.Ekegonchori (Kuria)Not specifiedTreeNot specified[37]Cassia didymobotrya Fres.Irebeni (Kuria), MuraoLeaves, roots, root barkShrubInfusion, decoction[37, 38, 40, 44]Cassia occidentalis L.Mnuka uvundo (Swahili)Leaves, rootsHerbDecoction[11, 17, 46]Dichrostachys cinereal L.Chinjiri (Digo)rootsTreeDecoction[17]Erythrina abyssinica Lam. ex DC.Omutembe (Kuria), Muhuti (Kikuyu)Root, barkTreeDecoction[3, 23, 34, 37, 38, 42]Indigofera arrecta A. RichNot reportedRootsHerbDecoction, chew directly[41]Mucuna giganteaOgombo (Luo)Not specifiedLianaNot specified[42]Senna didymobotrya (Fresen) Irwin & BarnebyOsenetoi (Maasai)Roots, leaves, bark, stemShrubDecoction[3, 23, 34, 41, 42, 67]Senna occidentalis (L.) LinkImbindiRootsShrubDecoction[34, 47]Tamarindus indica L.Muthumula (Kamba), Mkwadzu (Swahili)Bark, fruits, roots, leavesTreeDecoction, fruit eaten[17, 46, 47, 54]Tylosema fassoglenseNot reportedTuberClimberNot specified[56]HydnoraceaeHydnora abyssinica Schweinf.Muthigira (Kikuyu)Not specifiedHerbNot specified[3]HypericaceaeHarungana madagascariensis Lam. ex Poir.MusilaStem barkTreeDecoction[17, 34, 42]IcacinaceaePyrenacantha malvifolia Engl.Empalua (Maasai)RootsClimberNot specified[22]LamiaceaeAjuga integrifolia Buch. Ham.Imbuli yumtakhaAerial partsHerbDecoction[34]Ajuga remota Benth.Wanjiru (Kikuyu)Leaves, roots, whole plantHerbDecoction[3, 11, 23, 38, 44, 68, 69]Clerodendrum johnstonii OlivSingoruet (Nandi)LeavesShrubInfusion[34, 38]Fuerstia africana T.C.E.Fr.Kwa matsai, aremo (Luo)Aerial parts, leaves, whole plantHerbDecoction, infusion[34, 38, 44, 48, 65]Hoslundia opposita Vahl.Cheroronit, Cherungut (Nandi)Leaves, whole plantShrubDecoction[17, 38, 46, 50]Leucas calostachys OlivBware (Luo), LumetsaniLeaves, roots, aerial partsShrubDecoction[34, 37, 38]Leucas martinicensis (Jacq.) Ait.f.Chepkari (Nandi)FlowersHerbInfusion[38]Leonotis mollissima GuerkeNyanyondhi (Luo), Orbibi (Maasai)Leaves, rootsShrubDecoction[23, 37, 38]Leonotis nepetifolia (R. Br) Ait.f.Kipchuchuniet (Kipsigis)Not specifiedShrubDecoction[47, 70]Ocimum basilicum L.Sisiyat (Nandi)LeavesHerbDecoction[23, 46]Ocimum balansae Briq.Not reportedLeavesHerbDecoction[17]Ocimum gratissimum L. Suave wiild, O. tomentosum Oliv.Mukandu (Kamba)LeavesHerbDecoction[17, 23]Ocimum kilimandscharicum GuerkeMutaa (Kamba)Aerial partsHerbInhale steam[3, 34, 56]Ocimum lamiifolium BenthNot reportedRootsShrubDecoction[38]Ocimum suave WilldMurihani (Giriama)LeavesHerbDecoction[17, 46, 71]Plectranthus barbatus AndrewsKan’gurwet (Markweta)LeavesShrubInfusion, decoction[17, 34, 42, 46, 56, 58]Plectranthus sylvestris GurkeNot reportedLeavesHerbNot specified[58]Rotheca myricoides (Hochst.) Steane and Mabb (Clerodendrum myricoides (Hochst.) Vatke)Olmakutukut (Maasai), Munjuga iria (Kikuyu)Roots, leaves, root barkShrubDecoction[17, 34, 38, 42, 44, 48, 67]LauraceaeOcotea usambarensis Engl.Muthaiti (Kikuyu)Root barkTreeInfusion[3, 44]LoganiaceaeStrychnos henningsii GilgMuteta (Kamba, Kikuyu)Roots, leaves, stem barkTreeDecoction[3, 11, 44, 47, 55, 67]MalvaceaeAdansonia digitata L.Mbamburi (Swahili)LeavesTreeDecoction[17, 46]Azanza gackeana (F. Hoffm.) Excell & HillcoatMutoo (Kikuyu)Not specifiedTreeNot specified[3]Grewia bicolor JussEsiteti (Maasai)Not specifiedShrubNot specified[47]Grewia hainesiana HoleNot reportedLeavesShrubDecoction[17]Grewia hexamita BurretMkone (Digo)Roots, leavesShrubDecoction[46]Grewia plagiophylla K. SchumMkone (Digo)Bark, leavesNot specified[50]Grewia trichocarpa (Hochst) ex A. Rich.Cone (Digo)RootsShrubDecoction[17, 41, 46]Pavonia kilimandscharica GurkeChemanjililiet, Chepsabuni (Nandi)RootsHerbDecoction[38]Sida cordifolia L.Menjeiwet (Nandi)LeavesShrubInfusion[38]MeliaceaeAzadirachta indica A. JussMuarubaini (Kamba)Leaves, roots, barkTreeDecoction, inhalation, topical[3, 11, 17, 36, 43, 50, 54, 55, 72]Azadirachta indica (L) Burm.Mkilifi (Digo)Leaves, roots, root barkTreeDecoction[46, 73]Ekebergia capensis Sparrm.Olperre-longo (Maasai)BarkTreeDecoction[3, 48]Melia azedarach L.MwarubaineNot specifiedTreeNot specified[47]Melia volkensii L.Mukau (Kamba)BarkTreeDecoction[55]Melia azedarach L.Mwarubaini (Nandi)Leaves, barkTreeDecoction[34, 38, 42]Trichilia emetica Vahl.MunyamaBarkTreeDecoction[34, 72]Turraea mombassana C. DCOnchani Orok (Maasai)Leaves, root, fruitsShrubDecoction[67]Turraea robustaNot reportedRoot barkShrubDecoction[49]MelianthaceaeBersama abyssinica Fres.Kibuimetiet (Nandi)Root bark, bark, seedsTreeDecoction[38, 41]MenispermaceaeCissampelos mucronata A. Rich.MukoyeRootClimberRoot chewed[17, 34, 74, 75]Cissampelos pareira L.Karigi munanaRoot, root barkLianaDecoction[39]MoraceaeFicus bussei Warb ex Mildbr and BurretMgandi (Digo)Roots, leavesTreeDecoction[17, 46]Ficus cordata ThunbOladardar (Maasai)Branches, roots, stemTreeDecoction[67]Ficus sur. ForsskOmoraStem barkTreeDecoction[35]Ficus thonningii BlumeMutotoStem barkTreeDecoction[34]MyricaceaeMyrica salicifolia A. Rich.MurimaRoot barkTreeDecoction[44]MyrsinaceaeEmbelia schimperi VatkeKibong'ong'inik (Nandi)SeedsTreeDecoction[38]Maesa lanceolata ForsskKatera (Luo), Kibabustanyiet (Nandi)Roots, fruits, seeds, barkShrubDecoction[22, 34, 38, 76]MyrtaceaeEucalyptus globulus Labil.Mubau (Kikuyu)Not specifiedTreeNot specified[3]Psidium guajava L.Mapera (Luo)Leaves, fruitsTreeDecoction[36]OleaceaeJasminum floribunda R.Br.Not reportedRootHerbDecoction[41]Jasminum fluminense Vell.KipkoburoBark, stem, root tuberVineNot specified[77]Olea capensis L.Mutukhuyu, MucharageStem barkTreeDecoction[41, 44]Olea europaea L.Oloirien (Maasai)Inner/stem barkTreeDecoction[3, 22, 44, 45, 48]Ximenia americana L.Olamai (Maasai)LeavesTreeDecoction[47]OnagraceaeLudwigia erecta (L.) HaraMungeiWhole plantHerbInfusion, decoction[44, 52]OpiliaceaeOpilia campestris Engl.Enkirashai (Maasai)RootsShrubDecoction[22]OxalidaceaeOxalis corniculata L.Nyonyoek (Nandi)Whole plantHerbDecoction[38]PapilionaceaeCajanus cajan Millsp.Mucugu (Kikuyu)Not specifiedHerbNot specified[3]Dalbergia lactea VatkeMwaritha (Kikuyu)Not specifiedShrubNot specified[3]Ormocarpum trachycarpum (Taub.) HarmsMuthingii (Kamba)Bark, leavesShrubDecoction[52, 58]Rhynchosia hirta (Andrews) Meikle & Verdc.Tilyamook (Nandi)RootsLianaDecoction[38]Stylosanthes fruticosa (Retz.) AlstonKalaa (Kamba)Leaves, whole plantHerbInfusion[55]PassifloraceaePassiflora ligularis A. Juss.Hondo (Kikuyu)Not specifiedShrubNot specified[3]PiperaceaePiper capense L.f.Olerrubaat (Maasai)RootsHerbDecoction[48]PittosporaceaePittosporum lanatum Hutch. & BruceMunyamati (Kikuyu)Not specifiedHerbNot specified[3]Pittosporum viridiflorum SimsMunatiStem barkTreeDecoction[34, 44, 52]PoaceaePennisetum hohenackeri Hochst. ex SteudOlmakutian (Maasai)Bark, branches, rootsGrassDecoction[67]Rottboellia exaltata L.f.Mpunga (Digo)LeavesHerbDecoction[17, 46]Sporobolus stapfianusNot reportedNot specifiedHerbNot specified[45]PodocarpaceaePodocarpus latifolius (Thunb.) R.Br. ex Mirb.Enchani-enkashi (Maasai)RootsTreeDecoction[48]PolygonaceaeRumex abyssinicus Jacq.ShikachiLeavesHerbDecoction[34]Rumex steudelii Hochst ex A. RichAlukhavaRootsHerbDecoction[34]PolygalaceaeSecuridaca longifolia Poepp.Not reportedRootsTreeDecoction[17]Securidaca longipedunculata Fres.Mzigi (Digo)Roots, bark, leavesShrubDecoction[46]PrimulaceaeMyrsine africana L.Oseketeki (Maasai)Seeds, fruits, roots, multiple partsShrubDecoction[54, 67]RahmnaceaeRhamnus prinoides L.’HeritOrkonyil (Maasai)Roots, root barkShrubDecoction[3, 11, 35, 38, 44, 48, 69, 78]Rhamnus staddo A. RichOrkokola (Maasai), Ngukura (Kikuyu)Root bark, stem barkShrubDecoction[3, 11, 35, 44, 48, 69]Scutia myrtina (Burm. f.) KurzOsanankoruri (Maasai)Not specifiedShrubNot specified[3]RanunculaceaeClematis brachiata Thunb.Olkisusheeit (Maasai)Roots, root barkLianaDecoction[44, 48]RhizophoraceaeCassipourea malosana (Baker) AlstonMuthathi (Kikuyu)Not specifiedTreeNot specified[3]RosaceaePrunus africana (Hook. f.) KalkmanOrkujuk (Maasai), Muiri (Kikuyu)Bark, root, stem, stem barkTreeDecoction[3, 38, 44, 79, 80]Rubus pinnatus Wild.ButunduliLeaves, bark, fruitsShrubDecoction[3, 34]RubiaceaeAganthesanthemum bojeri Klotzsch.KahithimaWhole plantHerbNot specified[50]Agathisanthenum globosum (Hochst. ex A. Rich.) Bremek.Chivuma nyuchi (Digo)RootsHerbDecoction[17, 46]Canthium glaucum Hiern.Mhonga/Mronga (Digo)FruitsShrubDecoction[17, 46]Gardenia ternifolia subsp. JovistonatisKibulwaFruitsShrubDecoction[54]Keetia gueinzii (Sond.) BridsonMugukuma (Kikuyu)Not specifiedShrubNot specified[3]Pentanisia ouranogyne S. MooreChungu (Digo)RootsHerbDecoction[17, 46]Pentas bussei K. KrauseNot reportedRoot barkShrubDecoction[17]Pentas longiflora Oliv.Muhuha (Kikuyu), Cheroriet (Nandi)Bark, fruits, leaves, rootsShrubDecoction, rub on skin[3, 17, 38, 41, 61]Pentas lanceolata (Forssk.) DeflersOlkilaki-olkerr (Maasai)Root barkHerbDecoction[48]Rubia cordifolia L.Urumurwa (Kuria)Not specifiedHerbNot specified[37]Spermacoce princeae (K. Schum.) Verdc.OmonhabieboWhole plantHerbDecoction[35]Vangueria madagascariensisGmel (Vangueria acutiloba Robyns)MubiruStem barkShrubDecoction[44]Vangueria volkensii K.Schum.Kimoluet (Nandi)RootsShrubDecoction[38, 47]RutaceaeCitrus aurantiifolia (Christm.) SwingleMutimu (Kikuyu)Not specifiedTreeNot specified[3]Citrus limon (L.) Burm.f.Ndim (Luo)Fruits, leavesTreeEaten, decoction[36]Clausena anisata (Willd) Hook. f. ex Benth.Mtondombare (Digo), MukibiaLeaves, roots, bark, root barkShrubDecoction[17, 34, 41, 44, 46]Fagaropsis angolensis (Eng.) H.M. GardnerMurumu, mukuriampunguLeaves, roots, stem barkTreeDecoction[3, 23, 38, 44, 53]Fagaropsis angolensis (Eng.) DaleMukaragati (Kikuyu)Leaves, rootsTreeDecoction[3, 17, 46]Fagaropsis hildebrandtii (Engl.) Milne-Redh.Muvindavindi (Kamba)LeavesTreeDecoction[3, 81]Harrisonia abyssinica OliveOsiro (Luo), Orongoriwe (Kuria)Leaves, roots, root barkTreeDecoction[17, 23, 37, 44, 46, 47, 54, 82, 83]Teclea nobilisNot reportedStem barkShrubDecoction[11, 45]Teclea simplicifolia (Engl.) VerdoornMutuiu (Kamba), Munderendu (Kikuyu)Leaves, roots, stem barkShrubDecoction[3, 17, 44, 46, 55]Toddalia asiatica (L.) LamMururue (Kikuyu), Oleparmunyo (Maasai)Roots, root bark, leaves, fruits (multiple parts)ShrubDecoction[3, 11, 17, 44, 45, 47, 58, 59, 62, 67, 84]Zanthoxylum chalybeum Engl.Oloisuki (Maasai)Stem bark, root barkTreeDecoction[3, 17, 44, 46, 55, 61, 71, 85]Zanthoxylum gilletii (De Wild.) P.G. WatermanShihumba/ShikumaBarkTreeDecoction[34, 86]Zanthoxylum usambarense (Engl.) KokwaroOloisuki (Maasai)Root, fruits, bark, leaves, stemTreeDecoction[3, 11, 67, 78, 85]SalicaceaeDovyalis abyssinica (A. Rich.) WarbKaiyaba (Kikuyu)Leaves, rootsShrubDecoction[3, 38]Dovyalis caffra (Hook. f. & Harv.) WarbMukambura (Kikuyu)Not specifiedShrubNot specified[3]Flacourtia indica (Burm.f) Merr.Mtondombare (Digo)Roots, barkShrubDecoction[17, 46]Trimeria grandifolia (Hochst.) WarbOledat (Maasai)RootsShrubDecoction[3, 38, 47]SalvadoraceaeSalvadora persica L.Mukayau (Kamba)Root, stemShrubDecoction; prepared with salt and milk[22, 51, 63]SantalaceaeOsyris lanceolata Hochst. & SteudelOlosesiai (Maasai), muthithii (Kikuyu)Not specifiedShrubNot specified[3]SapindaceaeAllophylus pervillei Blume.Mvundza kondoLeaves, roots, barkShrubDecoction[50]Cardiospermum corundumNot reportedNot specifiedShrubNot specified[23]Pappea capensis (Spreng) Eckl. & Zeyh.Muba (Kikuyu), Enkorr irri (Maasai)BranchesShrubDecoction[3, 48]SapotaceaeManilkara butegiAnonBarkShrubDecoction[54]Mimusops bagshawei S. MooreLolwet (Nandi)Leaves, barkTreeDecoction[38]SolanaceaePhysalis peruviana L.MayengoLeavesShrubInhale steam[34]Solanum aculeastrum DunalMutura (Kikuyu)Not specifiedShrubNot specified[3]Solanum incanum L.Mutongu (Kamba), Entulelei (Maasai)Roots, leaves, root barkShrubDecoction[17, 34, 37, 44, 46, 87]Solanum taitense VatkeEntemelua (Maasai)RootsShrubChewed directly[22]Withania somnifera (L.) DunalMurumbae (Kikuyu)Root barkShrubDecoction[3, 44]UlmaceaeChaetacme aristate PlanchNot reportedRootsShrubDecoction[41]UrticaceaeUrtica massaica Mildbr.Thabai (Kikuyu)Aerial partsHerbDecoction[3, 35]VerbenaceaeClerodendrum eriophyllum GuerkeMuumbaRoot barkShrubDecoction[44, 52]Lantana camara L.Ruithiki, Mukenia (Kikuyu)LeavesShrubDecoction[3, 73]Lantana trifolia L.Ormokongora (Maasai)LeavesShrubDecoction[34, 72]Lippia javanica (Burm.f.) SprengAngware-Rao (Luo)RootsHerbNot specified[37, 58]Premna chrysoclada (Bojer) GürkeMvumaRoots, leavesHerbNot specified[50]VitaceaeCissus quinquangularis L.Not reportedNot specifiedHerbNot specified[45]Cyphostemma maranguense (Gilg) Desc.Mutambi (Kikuyu)Not specifiedHerbNot specified[3]Rhoicissus tridentata (L.f.) Wild & DrumNdurutua (Kikuyu)Bark, rootsShrubDecoction[3, 34, 38, 62]XanthorrhoeaceaeAloe deserti A. BergerNgolonje (Digo)LeavesHerbDecoction, infusion[17, 46]Aloe macrosiphon Bak.Golonje (Giriama)LeavesHerbInfusion[46]Aloe secundiflora Engl.Osukuroi (Maasai), Kiluma (Kamba)Leaves, leaf sap (exudate)HerbInfusion, decoction[11, 17, 34, 43, 44, 46, 58, 78, 88, 89]Aloe vera (L) Webb.Alvera (Digo)LeavesHerbInfusion[17, 46]Rhoicissus revoilliRabongo (Luo)ZingiberaceaeZingiber officinaleTangawizi (Luo)RootsHerbChewed[36]ZygophyllaceaeBalanites glabrus Mildbr. & Schltr.Orng’osua (Maasai)Not specifiedTreeNot specified[22]Balanites glabra Mildbr. & Schltr.Olng’osua (Maasai)BarkShrubDecoction[22]Balanites aegyptiaca (L.) Del.Olngosua (Maasai)BarkShrubDecoction[48]Language is also known as Kikamba. Local names with language(s) not indicated are sometimes a blend of Kiswahili and other local languages or were not specified by the authors. Decoction involves boiling a plant part in water. Infusion entails soaking of a plant part in water.Figure 1
Major botanical families from which antimalarial remedies are obtained in Kenya.Some of the plants such asAcacia mellifera has been reported for treatment of malaria in Somalia [24], Albizia coriaria Welw. ex Oliver, Artemisia annua L., Momordica foetida Schumach, Carica papaya L., and Catharanthus roseus (L.) G. Don in Uganda [25, 26], Cameroon [27], and Zimbabwe [28], Clematis brachiata and Harrisonia abyssinica Oliv in Tanzania [29] and South Africa [30], Artemisia afra in Ethiopia [31], and Tamarindus indica L., Carica papaya L., and Ocimum basilicum L. in Indonesia [32].


## 3.2. Growth Habit, Part(s) Used, Preparation, and Administration of Antimalarial Plants

Antimalarial plants used in Kenya are majorly shrubs (33.2%), trees (30.1%), and herbs (29.7%) (Figure2), and the commonly used plant parts are leaves (27.7%) and roots (19.4%) followed by bark (10.8%), root bark (10.5%), and stem bark (6.9%) (Figure 3). Comparatively, plant parts such as fruits, seeds, buds, bulbs, and flowers which have reputation for accumulating phytochemicals are rarely used, similar to reports from other countries [26, 28, 33].Figure 2
Growth habit of antimalarial plants used in Kenyan communities as per ethnobotanical surveys.Figure 3
Frequency of the reported plant parts used for preparation of antimalarial remedies in Kenya.The dominant use of leaves presents little threat to the survival of medicinal plants. This encourages frequent and safe utilization of the plants for herbal preparations. Roots and root structures such as tubers and rhizomes are rich sources of potent bioactive chemical compounds [33], but their frequent use in antimalarial preparations may threaten the survival of the plant species used. For example, Zanthoxylum chalybeum and African wild olive (Olea europaea) have been reported to be threatened due to improper harvesting methods [2]. Thus, proper harvesting strategies and conservation measures are inevitable if sustainable utilization of such medicinal plants are to be realized.Antimalarial remedies in Kenya are prepared by different methods. These include decoctions (70.5%), infusions (5.4%), ointments and steaming (1.3%), and roasting (0.3%). Preparation of antimalarial remedies from dry parts of one plant or several plants and ashes by using grinding stones was reported [38]. Burning, chewing, heating/roasting, pounding, and boiling or soaking in hot or cold water and milk were reported, and these are then orally administered as is the case with Western medicine [38]. Preparations for application onto the skin such as ointments, poultices, and liniments are frequently percutaneous, by rubbing or covering which are occasionally complimented by massage [38]. Rarely are antimalarial remedies administered through the nasal route. Fresh solid materials are eaten and chewed directly upon collection or after initial pounding/crushing. Dry plant materials are smoked and inhaled. These findings corroborate observations in other countries [33, 90–92].Malaria is caused by protozoan intracellular haemoparasites, and its treatment entails delivering adequate circulating concentration of appropriate antiprotozoal chemicals. The oral route is a convenient and noninvasive method of systemic treatment as it permits relatively rapid absorption and distribution of active compounds from herbal remedies, enabling the delivery of adequate curative power [93]. In addition, potential risk of enzymatic breakdown and microbial fermentation of active chemical entities may prompt the use of alternative routes of herbal remedy administration like inhalation of the steam or rubbing on the skin.In this survey, it was noted that few plant species are used for management of malaria simultaneously in different locations. This could probably be attributed to the abundant distribution of the analogue active substances among species, especially belonging to family Asteraceae, Euphorbiaceae, Fabaceae, Meliaceae, Rubiaceae, and Rutaceae. Differences in geographical and climatic conditions may also influence the flora available in a given region. However, some plants have a wider distribution and therefore are used by most communities [34].


## 3.3. Perception, Prevention, and Treatment of Malaria and Its Symptoms

In rural Kenya, some believe thatesse (malaria in native Tugen dialect) is caused by Cheko che makiyo (fresh unboiled milk), dirty water, ikwek (vegetables such as Solanum nigrum and Gynadropis gynadra) [54], mosquito bites, or cold weather [42]. Thus, burning of logs and plants such as Albizia coriaria with cow dung, Azadirachta indica (L) Burm (fresh leaves), Ocimum basilicum L., Ocimum suave Willd. (fresh leaves), and Plectranthus barbatus Andr. (ripe fruits or seeds) are done to keep mosquitoes away [17, 42]. Artemisia annua L. is planted in the home vicinity or near the bedroom window to repel mosquitoes believed to cause malaria [42].Except in the case of life-threatening illnesses or where there is concern that there may be some supernatural forces in the aetiology of the disease, malaria and its symptoms (periodic fever, sweating, headache, backache, and chills) are treated primarily using decoctions and infusions of plants. Whenever it is thought that malaria is due to supernatural forces, diviners (such asOrgoiyon among the Tugen and Oloiboni among the Maasai) are consulted [94]. Croton dichogamus Pax though used for normal malaria treatment is used by Oloiboni for treatment of malaria or other ailment(s) thought to be due to witchcraft [22]. According to indigenous diagnoses, malaria is due to the presence of excess bile in the body, so the bile has to be expelled before healing can take place. Thus, purgation is regarded as the key treatment regimen for malaria [22, 54].On the basis of this knowledge, different forms of herbal medications are prescribed according to the severity of the illness. Treatment of malaria is based on a number of interlinked elements: beliefs related to causation, the action or effectiveness of “modern” medicines, and the availability of plant treatments [54]. Salvadora persica L. is used for management of malarial colds, while Aneilema spekei (C. B. Clarke) is used for prevention of malaria fever [22]. The whole plant is mixed with other herbs in milk and sprinkled onto the patient. This is often administered by an Oloibon among the Maasai [22].Though single plant parts are often used, more than one plant part, for example, decoctions from a mixture of roots ofPlectranthus sylvestris together with those of Cassia didymobotrya and Clerodendrum johnstonii may be used as a remedy for malaria and headache [52]. Acacia species stem bark was reported to be used as a first treatment and is usually prepared as an overnight cold-water infusion, and then 40 ml is taken three times a day [11]. A follow-up medication would involve taking a decoction made from powders of Aloe species (leaf juice), Rhamnus staddo (stem or root bark), Clerodendrum myricoides (root bark), Warburgia ugandensis, Teclea nobilis (stem barks), and Caesalpinia volkensii, Ajuga remota Benth, Rhamnus prinoides, and Azadirachta indica leaves [11]. For this, 40 ml is taken thrice a day for 5 days.The popular method of preparation as decoctions and concoctions suggest that the herbal preparations may only be active in combination, due to synergistic effects of several compounds that are inactive singly [95]. It is possible that some of the compounds that are inactive in vitro could exhibit activity in vivo due to enzymatic transformation into potent prodrugs [96] as reported for Azadirachta indica extracts [97].


## 3.4. Adverse Side Effects, Antidotes, and Contraindications of Medicinal Plants in Kenya

In traditional context, the pharmacological effect of medicinal plants is generally ascribed to their active and “safe” content that will only exert quick effect when taken in large quantities [22, 33]. Most reviewed reports in this study did not mention the side effects of antimalarial preparations. Nevertheless, herbal preparations from some antimalarial plants were reported to induce vomiting, diarrhea, headache, and urination [22, 54] (Table 2). This may be due to improper dosage, toxic phytochemicals, or metabolic by-products of these preparations [22].Table 2
Side effects, antidotes, and contraindications of medicinal plants used for traditional management of malaria in Kenya.
PlantSide effectsAntidote(s)ContraindicationReference(s)Albizia anthelmintica Brongn.Induces vomiting, diarrhea, and bile release from the gall bladderNot reportedPregnant women[22]Aloe volkensii L.Induces vomitingNot reportedChildren[22]Balanites glabrus Mildbr. & Schltr.Induces vomiting, diarrhea, and bile release from the gall bladderNot reportedPregnant women[22]Croton megalocarpoides Friis & M.G. GilbertStomachache, induce vomiting, and bile release from the gall bladderNot reportedNot reported[22]Euphorbia meridionalis Bally & S. CarterInduces diarrhea as a means of cleansing the bodyTaken with goat or sheep soupNot reported[22]Momordica friesiorum Hams C. JeffreyInduces vomiting and bile release from the gall bladderNot reportedNot reported[54]Opilia campestris Engl.Induces vomiting and bile release from the gall bladderMixed with soupNot reported[22]Pyrenacantha malvifolia Engl.Induces vomitingNot reportedPregnant women[22]Salvadora persica L.Induces vomiting and bile releaseMilk, saltNot reported[22]Sericocomopsis hildebrandtii Schinz.Stomachache, weight loss through induced vomiting, and bile release from the gall bladderMilkPregnant women[22]However, purgation and emesis are interpreted as signs that malaria is leaving the body and that the healing process has begun [22, 54]. It is reasonable that some side effects might also be masked through the use of more than one plant (or plant parts) especially for bitter remedies (such as Ajuga remota Benth.) [11, 38]. However, some herbalists are known to use more than one plant (plant parts) as a trick of keeping the secrecy of their formula [11]. Boiling of plant parts in goat fat, meat bone broth (as is done for Carissa edulis), taking decoctions mixed with milk (for Rhamnus prinoides), and mixing remedies with milk and salt for Salvadora persica L. [22] could serve as antidotes for potential side effects from use of the herbal preparations as reported elsewhere [33]. Some of the plants reported in this study such as Ajuga integrifolia and Croton macrostachyus were reported in Ethiopia to cause vomiting, nausea, headache, urination, and diarrhea when used for management of malaria [33]. Because the outcome of the treatment remains generally unclear due to lack of feedback from patients, herbalists rely on anecdotal reporting as far as efficacy and side effects are concerned.Some antimalarial plants were reported as contraindicated to pregnant women and children (Table2). Gathirwa et al. [50] reported that the posology of antimalarial herbal preparations in Kenya sometimes is dictated by the plant to be used, the traditional herbalist, the sex and the age of the patient, reiterating that pregnant women and children are often given lower dosages compared to other adults. This indicates the existence of research gaps with regard to the potential toxicities and corresponding counteracting mechanisms of antimalarial plants in Kenya. This gap represents a barrier to effective development and exploitation of indigenous antimalarial plants. In essence, some of the plants listed are reported to exhibit marked toxicity. Teclea simplicifoli (roots) is regarded to be poisonous by rural Kenyans [98]. Catharanthus roseus (L.) G. Don is another such plant known to house neurotoxic alkaloids [99]. Vincristine and vinblastine in this plant are highly cytotoxic antimitotics that block mitosis in metaphase after binding to mitotic microtubules [100]. Side effects such as kidney impairment, nausea, myelosuppression, constipation, paralytic ileus, ulcerations of the mouth, hepatocellular damage, abdominal cramps, pulmonary fibrosis, urinary retention, amenorrhoea, azoospermia, orthostatic hypotension, and hypertension [101–103] have been documented for antitumor drugs vincristine and vinblastine derived from this plant. These observations could partly explain why some antimalarial herbal preparations in Kenya are ingested in small amounts, applied topically, or are used for bathing. This gives a justification for the investigation of the plants for their potential toxicity.


## 3.5. Other Ethnomedicinal Uses of Antimalarial Plants Used in Rural Kenya

Most of the antimalarial plant species identified are used for traditional management of other ailments in Kenya and in other countries.Ajuga remota Benth (different parts), for example, are used to relieve toothache, severe stomachache, oedema associated with protein-calorie malnutrition disorders in infants when breast-feeding is terminated, pneumonia, and liver problems [52, 104, 105]. Such plants are used across different ethnic communities for managing malaria and can be a justification of their efficacy in malaria treatment [19].


## 3.6. Toxicity, Antiplasmodial, and Antimalarial Studies

Table3 shows the list of some of the antimalarial plants used in Kenya with reports of toxicity/safety, antimalarial, and antiplasmodial activity evaluation. Across African countries, many antimalarial plants captured in this review have demonstrated promising therapeutic potential on preclinical and clinical investigations [68, 106–111]. Interestingly, antimalarial compounds have been identified and isolated from some of these species [62, 112].Table 3
Antiplasmodial/antimalarial activities of investigated plants used for malaria treatment in Kenya and their active chemical constituents.
PlantPart usedExtracting solventAntiplasmodial (IC50 μg/ml)/antimalarial activity (Plasmodium strain)Active phytochemicals and toxicity informationReference (s)Justicia betonica L.ShootMethanol, water, ether69.6 (K39), >100 (K39), 13.36μg/mlJustetonin (indole(3,2-b) quinoline alkaloid glycoside)[117, 118]Allium sativum L.SyntheticEthanol50 mg/kg of ajoene suppressed development of parasitemia; ajoene (50 mg/kg) and chloroquine (4.5 mg/kg), given as a single dose, prevented development of parasitemiaAjoene, nontoxic[119]Acmella caulirhizaWhole plantDichloromethane9.939 (D6); 5.201 (W2)No reports[56]Aloe kedongensis ReynoldsLeavesMethanol87.7 (D6); 67.8 (W2)Anthrone, C-glucoside homonataloin, anthraquinones, aloin, lectins[120, 121]Aloe secundiflora Eng.Leaf exudateTested direct66.20 (K39)No reports[58]Achyranthes aspera L.Leaf, stem, roots, seedsEthanol>100, 76.75, >100, >100μg/mlAlkaloids, glycosides, saponins, triterpenoids[122]Artemisia annua L.LeavesWater1.1 (D10), 0.9 (W2)Sesquiterpenes and sesquiterpene lactones including artemisinin; safe and effective; artemisinin is safe for pregnant women[120, 123, 124]Bidens pilosa L.LeavesDichloromethane, chloroform, water, and methanol8.5, 5, 11, 70 (D10)No reports[76]Maytenus undata (Thunb.) BlakelockLeavesDichloromethane, dichloromethane/chloroform (1 : 1), methanol, water>100, 21, 60, >100 (D10)No reports[76]StemDichloromethane, dichloromethane/chloroform (1 : 1), methanol, water85, 24, 38, >100 (D10)RootsDichloromethane, chloroform, methanol, water23, 36, 40, >100 (D10)Rhus natalensis Bernh. ex KraussStem bark, leavesEthanol>50 (FcB1)Triterpenoids[50, 125]Leaves, rootsMethanol43.92 (D6), 51.2 (W2); >100 (D6), 80.44 (W2)Carissa edulis (Forssk.) VahlStem bark, root bark, rootsDichloromethane, chloroform, water, and methanol33 (D10), 6.41 (D6), >250, 148.53 and >250, >250 against ENT 30, and NF 54, respectivelyLignan, nortrachelogenin, cytotoxicity IC50 > 20, LD50 of 260.34, and 186.71 μg/ml for water and methanol extracts[48, 53, 76]Euphorbia tirucalli L.LeavesDichloromethane, dichloromethane/methanol (1 : 1), methanol, water12, 23.5, >100, 83 (D10)No reports[76]Psiadia punctulataTwigsDichloromethane, water9, >100 (D10)No reports[76]LeavesDichloromethane, dichloromethane/methanol (1 : 1), water14, 22.5, >100 (D10)Whole plantDichloromethane/methanol (1 : 1), water18 (D10), >100 (D10)Ricinus communis L.LeavesDichloromethane/methanol (1 : 1), water27.5, >100 (D10)No reports[76]StemsDichloromethane/methanol (1 : 1), water8, >100 (D10)FruitDichloromethane/methanol (1 : 1), water90, >100 (D10)Catharanthus roseus G. DonLeavesMethanol4.6 (D6); 5.3 (W2)Has neurotoxic alkaloids, terpenoids, flavonoids, sesquiterpenes[57, 126]Caesalpinia volkensii HarmsLeavesDecoction, ethanol, petroleum ether, methanol, water480, 481, 490, 858, 404 (FCA: 20 GHA), 923, 960, 250, 961, 563 (W2)No reports[11]Artemisia afra Jacq. ex WilldLeavesMethanol9.1 (, D6); 3.9 (W2)Acacetin, genkwanin, 7-methoxyacacetin; cytotoxicity observed in Vero cells[57, 127]Microglossa pyrifolia (Lam.) O. KtzeLeavesChloroform, dichloromethane<5 (both NF54 and FCR3)E-Phytol, 6e-geranylgeraniol-19-oic acid; cytotoxic to human foetal lung fibroblast cell lines[18, 25, 128, 129]Cucumis aculeatus CognFruitWater>30No reports[62]Schkuhria pinnata (Lam.)Whole plantWater22.5 (D6); 51.8 (W2)Schkuhrin I and schkuhrin II; methanol extract: low cytotoxicity against human cells; aqueous extracts: no toxicity observed in mice[57, 130]Solanecio mannii (Hook. f.) C. JeffreyLeavesMethanol21.6 (3D7); 26.2 (W2)Phytosterols,n-alkanes, and N-hexacosanol[120, 128]Tagetes minuta L.LeavesEthyl acetate61.0% inhibition at 10μg/mlNo reports[130]Tithonia diversifolia A. GrayLeaves, aerial partsMethanol, ether1.2 (3D7), 1.5 (W2), methanolic extract had 74% parasitemia suppressionTagitinin C and sesquiterpene lactones; aerial parts are cytotoxic against cells from the human foetal lung fibroblast cell line.[128, 131–133]Vernonia amygdalina Del.LeavesMethanol/dichloromethane, ethanol2.7 (K1), 9.83.In vivo parasite suppression of between 57.2 and 72.7% in combination with chloroquineVernolepin, vernolin, vernolide, vernodalin and hydroxy vernodalin, and steroid glucosides; petroleum ether extract shows strong cytotoxicity[111, 120, 130, 131, 134, 135]Vernonia auriculifera (Welw.) HiernLeavesEthane, chloroform, ethyl acetate, water>100, 37.7, 40.3, 55.2, >100 (K39)No reports[35]Vernonia brachycalyx O. Hoffm. SchreberLeavesChloroform/ethyl acetate, methanol6.6, 31.2 (K39) 29.6, 30.2 (V1/S)5-Methylcoumarin isomers, 16,17-dihydrobrachycalyxoloid[58]Vernonia lasiopus O. Hoffm.LeavesMethanol44.3 (D6); 52.4 (W2)Sesquiterpene lactones, polysaccharides[57, 120]Markhamia lutea (Benth.) K. Schum.LeavesEthyl acetate71% inhibition ofP. falciparum at 10 μg/mlPhenylpropanoid glycosides, cycloartane triterpenoids, musambins A-C, Candmusambiosides A-C[130, 136]Spathodea campanulataStem bark, leavesEthyl acetate, ethanol28.9% inhibition ofP. falciparumQuinone (lapachol)[130, 137, 138]Cassia didymobotrya Fres.LeavesMethanol23.4 (D6); undetectable (W2)Alkaloids[57]Warbugia ugandensis SpragueStem barkMethanol, water6.4 (D6); 6.9 (W2), 12.9 (D6); 15.6 (W2)Coloratane sesquiterpenes, e.g., muzigadiolide[57, 131, 139–141]Dichloromethane69% parasite inhibitionCarica papaya L.LeavesEthyl acetate2.96 (D10), 3.98 (DD2)Alkaloids, saponins, tannins, glycosides; no serious toxicity reported; carpaine, an active compound againstP. falciparum had high selectivity and was nontoxic to normal red blood cells[142, 143]Maytenus senegalensisRootsEthanol1.9 (D6), 2.4 (W2)Terpenoids, pentacyclic triterpenes, e.g., pristimerin; no toxicity observed in ethanol extract[144, 145]Ethulia scheffleri S.MooreLeavesChloroform/ethyl acetate/methanol49.8 (K39), 32.2 (V1/S)No reports[58]Combretum molle G. DonStem barkAcetone8.2 (3D7)Phenolics, punicalagin[146]Momordica foetida SchumachShootWater6.16 (NF54); 0.35 (FCR3)Saponins, alkaloid, and cardiac glycosides; no pronounced toxicity against human hepatocellular (HepG2) and human urinary bladder carcinoma (ECV-304, derivative of T-24) cells[25, 134, 147]Clutia abyssinica Jaub. & SpachLeavesMethanol7.8 (D6); 11.3 (W2)Diterpenes[57]Croton macrostachyus Olive.LeavesChloroform, dichloromethaneChemotherapeutic effect of 66–82%, 2 (D6)Triterpenoids including lupeol[14, 56]Flueggea virosa (Roxb. ex Willd) VoigtLeavesWater/methanol2.0 (W2)Bergenin, nontoxic, extracts exposed to murine macrophages did not slow or inhibit growth of cells[148, 149]Erythrina abyssinica Lam.Stem barkEthyl acetate83.6% inhibition ofP. falciparum at 10 μg/mlChalcones (5-prenylbutein and homobutein), flavanones including 5-deoxyabyssinin II, abyssinin III, and abyssinone IV[130, 137]Kigelia africana (Lam.) BenthBark, fruitChloroform/ethyl acetate, methanol59.9 (K39), 83.8 (V1/S); fruits had 165.9 (K39)No reports[58]Trichilia emetica VahlLeaves, twigsDichloromethane/methanol (1 : 1)3.5 for all (D10)Kurubasch aldehyde[76, 150]Senna didymobotrya (Fresen.) H. S. Irwin & BarnebyLeaves, twigsMethanol, dichloromethane/methanol (1 : 1)>100 (K39), 9.5 (D10)Quinones[35, 76, 117]Tamarindus indica L.Stem barkWater25.1% chemosuppressive activity at 10 mg/kg (P. berghei)Saponins (leaves), tannins (fruits)[73]Harungana madagascariensis Lam.Stem barkWater, ethanol9.64 (K1); <0.5 with 28.6–44.8% parasite suppressionQuinones including bazouanthrone, ferutinin A, harunganin, harunganol A, anthraquinones, saponins, steroids[137, 151–153]Rotheca myricoides (Hochst.) Steane and MabbLeavesMethanol9.51–10.56 and 82% parasite suppression at 600 mg/kgNo reports[154]Leucas calostachys Oliv.LeavesMethanol3.45 with parasite inhibition of 3.5–5.2%No reports[82]Ajuga remota Benth.Whole plantEthanol; decoction, ethanol, petroleum ether, methanol, and water55 (FCA/GHA), 57 (W2); 937, 55, 149, 504, 414 (FCA/GHA), 371, 57, 253, 493, 101 (W2)Ajugarin-1, ergosterol-5,8-endoperoxide, 8-oacetylharpagide, steroids[11, 14]Suregada zanzibariensis BaillRoot barkWater, methanol≤10 (K67), (ENT36)Alkaloids[96, 155]Clerodendrum myricoides R. Br.Root barkEthanol4.7 (D6); 8.3 (W2)No reports[156, 157]Chloroform>10 (D6)Cytotoxicity, IC50 > 20.0 μg/ml[48]Hoslundia opposita Vahl.LeavesEthyl acetate66.2% inhibition ofP. falciparum at 10 μg/mlQuinones, saponins, abietane diterpenes (3-obenzoylhosloppone)[50, 130]Roots; aerial partsMethanol79.38 (D6), 64.21 (W2); 19.73 (D6), 29.41 (W2)Leonotis nepetifoliaLeavesEthyl acetate, dichloromethane/methanol (1 : 1), water27.0% inhibition ofP. falciparum at 10 μg/ml, 15, >100 (D10)No reports[76, 130]Ocimum basilicum L.Leaves, whole plantEthanol68.14 (3D7); 67.27 (INDO)No reports[156, 157]Ocimum gratissimum WildLeaves/twigsDichloromethane8.6 (W2)Flavonoids[56, 158]Ocimum suave WildLeavesWater (hot), chloroform/methanol mixture100 mg/kg/day of extracts provided 81.45% and 78.39% parasite chemosuppression[71]Plectranthus barbatus AndrewsLeavesDichloromethaneNo activityNo toxicity recorded[56, 71]Root barkWater (hot), chloroform/methanol mixture100 mg/kg/day of extracts had 55.23% and 78.69% parasite chemosuppressionAzadirachta indica A. Juss.LeavesWater, methanol17.9 (D6); 43.7 (W2)Terpenoids, isoprenoids, gedunin, limonoids: khayanthone, meldenin, and nimbinin; cytotoxicity LD50 of 101.26 and 61.43 μg/ml for water and methanol extracts[53, 144, 158–160]Melia azedarachLeavesMethanol, dichloromethane55.1 (3D7), 19.1 (W2); 28No reports[161, 162]Ficus thonningii BlumeLeavesHexane10.4No reports[163]Cissampelos mucronata A. Rich.Root bark, rootMethanol, ethyl acetate8.8 (D6); 9.2 (W2); root extract <3.91 (D6), 0.24 (W2) for the active compound (curine)Benzylisoquinoline alkaloids, curine[74, 75, 157]Acacia nilotica L.Stem barkMethanol100 mg/kg produced 77.7% parasitic inhibitionTannins, flavonoids, terpenes[53, 164]Water, methanol>250, 153.79 (ENT 30), 73.59, 70.33 (NF 54)LD50 of 368.11 and 267.31 μg/ml for water and methanol extractsAlbizia coriaria Welw. ex OlivStem barkMethanol15.2 (D6); 16.8 (W2)Triterpenoids, lupeol, lupenone[57]Ageratum conyzoides L.Whole plantDichloromethane, methanol2.15 (D6); 3.444 (W2), 11.5 (D6); 12.1 (W2)Flavonoids[57]Albizia zygia (DC.) Macbr.Stem barkMethanol1.0 (K1)Flavonoids mainly 3′,4′,7-trihydroxyflavone; aqueous extract is relatively safe on subacute exposure[165, 166]Maesa lanceolata Forsk.TwigDichloromethane: methanol (1 : 1)5.9 (D10)Lanciaquinones, 2,5, dihydroxy-3-(nonadec-14-enyl)-1,4-benzoquinone[76, 128, 167]Securidaca longipedunculata Fresen.LeavesDichloromethane6.9 (D10)Saponins, flavonoids, alkaloids, steroids[168]Prunus africana (Hook. f.) KalkmanStem barkMethanol17.3 (D6); not detected (W2)Terpenoids[57]Pentas longiflora Oliv.RootMethanol0.99 (D6); 0.93 (W2)Pyranonaphthoquinones, pentalongin and psychorubrin, and naphthalene derivative mollugin; low cytotoxicity[169]Teclea nobilis DelileBark70% ethanol53.27% suppression of parasitemia at 700 mg/kgTannins, alkaloids, saponins, flavonoids[167, 170]Ethyl acetate54.7% inhibition ofP. falciparum at 10 μg/mlQuinoline alkaloids[130]Toddalia asiaticaRoot bark, fruits, and leavesMethanol, water, ethyl acetate, hexane6.8 (D6); 13.9 (W2); ethyl acetate fruit extract (1.80 mg/ml), root bark aqueous (2.43) (W2)Furoquinolines (nitidine and 5,6-dihydronitidine), coumarins; acute and cytotoxicity of the extracts, with the exception of hexane extract from the roots showed LD50 > 1000 mg/kg and CC50 > 100 mg/ml, respectively[84, 157]Zanthoxylum chalybeum Engl.Stem barkWater4.3 (NF54); 25.1 (FCR3)Chelerythine, nitidine, and methyl canadine; no toxicity recorded[25, 71]Trimeria grandifolia (Hochst.) Warb.LeavesMethanol>50 (3D7)No reports[128]Harrisonia abyssinica Olive.RootsWater, methanol4.4 (D6), 10.25 (W2); 89.74, 79.50 (ENT 30); 86.56, 72.66 (NF 54)Limonoids and steroids; LD50 of 234.71 and 217.34 μg/ml for water and methanol extracts[53, 144]Lantana camara L.Leaves, leaves/twigsDichloromethane, dichloromethane/methanol (1 : 1), water8.7 (3D7), 5.7 (W2), 11 (D10), >100 (D10), >100 (D10)Lantanine, sesquiterpenes, triterpenes, flavonoids[76, 171]Flacourtia indica (Burm. f.) Merr.RootsDichloromethane, dichloromethane/methanol (1 : 1), water86.5 (D10), 78 (D10), >100 (D10)No reports[76]Clausena anisataTwigs, leavesDichloromethane/methanol (1 : 1), water18 (D10), >100 (D10); 55, >100 (D10)No reports[76]Flueggea virosa (Roxb.ex Willd.) Baill.Leaves/twigsDichloromethane/methanol (1 : 1), water19 (D10), 11.4 (D10)Alkaloids: Securinine and viroallosecurinine had IC50 of 2.7 and 2.9Alkaloids, bergenin (root bark), securinine, and viroallosecurinine[76, 172–174]Lantana trifolia L.Ariel partsPetroleum ether, chloroform, ethanol13.2, >50, >50 (plasmodial lactate dehydrogenase)Steroids, terpenoids, alkaloids, saponins[125]Bridelia micrantha (Hochst.) Baill.Stem bark, leavesMethanol158.7 (K1)No reports[175]Balanites aegyptiaca (L.) Del.Root barkChloroform3.49 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Sericocomopsis hildebrandtiiRoot barkChloroform3.78 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Boscia angustifoliaInner barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Acacia tortilisRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Commiphora schimperiInner barkChloroform4.63 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Acacia melliferaInner barkChloroform4.48 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Fuerstia africanaLeaf, aerial parts, leavesChloroform, petroleum ether, methanol3.76 (D6), 1.5, <15 with >70% parasite suppressionFerruginol, cytotoxicity IC50 > 20 μg/ml[48, 65, 131, 176]Psiadia punctulataRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Ajuga integrifolia Buch.-HamLeavesMethanol35.17% at 800 mg/kg/day parasite suppressionAlkaloids, flavonoids, saponins, terpenoids, anthraquinone, steroids, tannins, phenols, and fatty acids; no lethal effect on mice in 24 h and within 10 days of observation[177]Albizia gummiferaMethanol0.16 (NF54), 0.99 (ENT 30) for alkaloidal fraction, spermine alkaloids had parasite suppression of 43–72%Spermine alkaloids (budmunchiamine K, 6-hydroxybudmunchiamine K, 5-normethylbudmunchiamine K, 6-hydroxy-5-normethylbudmunchiamine K, 9-normethylbudmunchiamine K)[178]Rhamnus staddoRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Ocimum kilimandscharicumLeaves, twigsDichloromethane0.843 (D6); 1.547 (W2)No reports[56]Gutenbergia cordifoliaLeavesChloroform0.4 (D6)Cytotoxicity IC50 = 0.2 μg/ml[48]Piper capenseRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Pentas lanceolataRoot barkChloroform5.15 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Clematis brachiataRoot barkChloroform4.15 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Ekebergia capensisInner bark, fruit, twigsChloroform, dichloromethane/methanol (1 : 1)3.97 (D6), 10, 18 (D10)Cytotoxicity IC50 > 20 μg/ml[48, 76]Rhamnus prinoidesRoot barkChloroform3.53 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Olea europaea ssp. AfricanaInner bark, leaves, twigsChloroform, dichloromethane/methanol (1 : 1)9.48 (D6), 12, 13 (D10)Cytotoxicity IC50 > 20 μg/ml[48, 76]Pappea capensisInner barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Pittosporum viridiflorum SimsWhole plant, leaves/flowersDichloromethane, methanol, dichloromethane/methanol (1 : 1)3, 10, 27.7, (D10), 28, 47, 70.5 (D10)Triterpenoid estersaponin, pittoviridoside (saponins)[76, 179, 180]Podocarpus latifoliusRoot barkChloroform6.43 (D6)Cytotoxicity IC50 > 20 μg/ml[48]Rumex abyssinicus Jacq.RootDichloromethane<15No reports[176]Rubus pinnatus WildLeavesEthanol20% parasite suppressionNo reports[130]Zanthoxylum gilletiiStem barkDichloromethane/methanol (1 : 1)2.52 (W2), 1.48 (D6), 1.43 (3D7)Nitidine, seas amine 8-acetyl dihydrochelerythrine[86, 176]Solanum incanum L.LeavesChloroform/methanol31% parasite suppressionNo reports[87]Rhoicissus tridentataRootsWater>40.0No reports[62]Acacia hockiiRoot barkChloroform>10.0 (D6); not activeCytotoxicity IC50 > 20 μg/ml[48]Lippia javanica (Burm.f.) SprengRootsChloroform/ethyl acetate, methanol16.7, 40.6 (K39), 19.2, 40.1 (V1/S)No reports[58, 76]Roots, stemDichloromethane, methanol, dichloromethane/methanol (1 : 1)3.8, 27, 24 (D10), 4.5, 21.8, 29.8 (D10)Premna chrysoclada (Bojer) GürkeRoots, leavesMethanol27.63 (D6), 52.35 (W2); 7.75 (D6), 9.02 (W2)Not cytotoxic at 100μg/ml[50]Allophylus pervillei BlumeRoots, stem barkMethanol45.62 (D6), 48.91 (W2); >100 (D6),>100 (W2)Not cytotoxic at 100μg/ml[50]Aganthesanthemum bojeri Klotzsch.Whole plantMethanol55.3 (D6), 55.97 (W2)Not cytotoxic at 100μg/ml[50]Abrus precatorius L.LeavesMethanol85.59 (D6), >100 (W2)Not cytotoxic at 100μg/ml[50]Combretum illairii Engl.Stem bark, leavesMethanol55.96 (D6), 58.54 (W2); 24.21 (D6), 33.31 (W2)Not cytotoxic at 100μg/ml[50]Grewia plagiophylla K. SchumLeaves, stem barkMethanol13.28 (D6), 34.2 (W2); >100 (D6), >100 (W2)Not cytotoxic at 100μg/ml[50]Combretum padoides Engl. & DielsRootsMethanol21.73 (D6), 59.43 (W2)Not cytotoxic at 100μg/ml[50]Uvaria acuminataLeaves, rootsMethanol51.13 (D6), >100 (W2); 8.89 (D6), 6.90 (W2)Cytotoxic with CC50 of 2.37 μg/ml.[50]Ormocarpum trachycarpumRootsChloroform/ethyl acetate, methanol, water19.6, 41.7, 79.4 (K39); 17.5, 32.8 (V1/S)No reports[58]Plectranthus sylvestris GurkeLeavesChloroform/ethyl acetate, methanol41.1, 56.2 (K39); 61.0 (V1/S)No reports[58]Turraea robustaRoot barkWater, methanol25.32, 2.09 (D6), 42.41, 10.32 (W2)IC50 of 24.38 and 45.72 μg/ml for methanol and aqueous extracts against Vero cells (cytotoxic)[49]Lannea schweinfurthiiStem barkWater, methanol10.55 and 75.90, 11.38 and 36.26 (D6 and W2)IC50 of 225.25 and 3256.52 μg/ml for methanol and aqueous extracts against Vero cells[49]Sclerocarya birreaStem barkWater, methanol18.96 and 71.74, 5.91 and 24.96 (D6 and W2)IC50 of 361.24 and 3375.22 μg/ml for methanol and aqueous extracts against Vero cells[49]Withania somniferaStem barkWater, methanol>250, >250 (ENT 30); 145.86, 125.59 (NF 54)LD50 of 301.44 and 207.27 μg/ml for water and methanol extracts[53]Zanthoxylum usambarenseStem barkWater, methanol14.33, 5.25 (ENT 30); 5.54, 3.20 (NF 54)LD50 of 260.90 and 97.66 μg/ml for water and methanol extracts[53]Fagaropsis angolensisStem barkWater, methanol10.65, 6.13 (ENT 30); 5.04, 4.68 (NF 54)LD50 of 173.48 and 57.09 μg/ml for water and methanol extracts[53]Myrica salicifoliaStem barkWater, methanol85.97, 66.84 (ENT 30); 55.89, 51.07 (NF 54)LD50 of 328.22 and 320.17 μg/ml for water and methanol extracts[53]Strychnos henningsii GilgStem barkWater, methanol73.39, 67.16 (ENT 30); 190.0, 159.71 (NF 54)LD50 of 293.93 and 101.22 μg/ml for water and methanol extracts[53]Neoboutonia macrocalyxStem barkWater, methanol92.85, 84.56 (ENT 30); 78.44, 78.40 (NF 54)LD50 of 41.69 and 21.04 μg/ml for water and methanol extracts[53]Urtica massaica Mildbr.Aerial partsHexane, chloroform, ethyl acetate, water, methanol>100 (K39)No reports[35]Uvaria scheffleri DielsLeaves, stem, root barkPetroleum ether, dichloromethane, methanol5–500 (K1)Indole alkaloid-(±L)-schefflone, uvaretin, diuvaretin[181, 182]Rauwolfia cothenRoot barkPetroleum ether, dichloromethane, methanol0–499 (K1)Yohimbine, an indole alkaloid[183, 184]Tridax procumbens L.Whole plantDichloromethane/methanol (1 : 1), water17 (D10), >100 (D10)Bergenin[76, 184, 185]Centella asiaticaLeavesDichloromethane/methanol (1 : 1)8.3 (D10)Alkaloids, sesquiterpenes[76, 186]Ficus surStem barkHexane, chloroform, ethyl acetate, water, methanol19.2, 9.0, >100, >100, >100 (K39)No reports[35]Euphorbia inaequilatera Sond.Whole plantHexane, chloroform, ethyl acetate, water, methanol19.2, 9.0, >100, >100, >100 (K39)No reports[35]Spermacoce princeae (K. Schum.) Verdc.Whole plantHexane, chloroform, ethyl acetate, water, methanol>100 (K39)No reports[35]Senna occidentalisLeavesDimethyl sulfoxide, ethanol48.80 (3D7), 54.28 (NIDO); <3;Quinones[156, 187, 188]Ethanol, dichloromethane>60% parasitemia suppressionSearsia natalensis (Bernh. ex C. Krauss)LeavesChloroform1.8 (plasmodial lactate dehydrogenase)No reports[125]Plasmodium falciparum isolates: D6, 3D7, D10, FCA/GHA (FCA: 20 GHA), FCR3, K39, and NF54 are chloroquine sensitive; DD2, ENT 30, FCR3, K1, NIDO, V1/S, and W2 are chloroquine resistant. For [48], control used for cytotoxicity study (vinblastine) had the effective dose to inhibit 50% growth (ED50) = 0.038 μg/ml. An ED50 greater than 20 μg/ml indicates that the plant extract lacks cytotoxicity. The control drug chloroquine had a toxicity of 17.4 μg/ml and IC50 of 0.004 μg/ml against D6 clone.Export of indigenous medicinal plants bring substantial foreign exchange to African countries such as Egypt [113], South Africa [114], Uganda, Tanzania, and Kenya [115]. Despite the success of traditional practices and abundance of indigenous medicinal plants (Table 1), antimalarial plants research in Kenya stops mostly on ethnobotanical surveys, with extensions limited to evaluation of crude extracts from plants against Plasmodium berghei [48, 56, 71]. A gap is evident with regard to research geared towards identifying and isolating plant bioactive compounds and establishing the efficacy and safety of medicinal plants through in vitro assays using human Plasmodium parasites and in vivo assay involving higher animal models and randomized clinical trials [50]. For example, the toxicity of 16,17-dihydrobrachycalyxolid isolated in Vernonia brachycalyx has been reported to be due to its ability to inhibit the proliferation of phytohaemmaglutinin-treated human lymphocytes [116]. A median inhibitory concentration (IC50) of 7.8 μg/ml was reported, which is comparable to the median concentration obtained in the antiplasmodial assay by Oketch-Rabah et al. [58] (Table 3). To assess whether observed antiplasmodial activities are due to a specific or a general toxicity effect, the experimental selectivity index (SI) needs to be calculated for extracts and only a few studies in Kenya has attempted this [48–50]. It is worth noting that there is always a variation in the degree of toxicity depending on the sensitivity of the animals, tissue, or cells used, type of extract, nature of the test substance, dose, and mode of administration. In this study, 38.8% (54/139) of the total plants were evaluated for their toxicities. Of these, 41 showed low cytotoxicity with LC50 > 20 μg/ml. Some of these plants such as Artemisia annua, Carica papaya, Flueggea virosa, and Schkuhria pinnata fortuitously showed good antimalarial activity. On the contrary, extracts of some plants used for malaria treatment with good activity are potentially toxic, for example, dichloromethane leaf extract of Microglossa pyrifolia, methanolic extract of Uvaria acuminata (CC50 = 2.37 μg/ml), and petroleum ether leaf extract of Vernonia amygdalina.In total, 139 (48.6%) of the species identified have been investigated for antiplasmodial (n = 25, 18%) or antimalarial activities (n = 135, 97.1%). However, there is no record on antiplasmodial or antimalarial activity of about 51.4% of the species used although they could be potential sources of antimalarial remedies. In the antiplasmodial activity, parasite suppression ranged from 3.5 to 5.2% in Leucas calostachys Olive aqueous leaf extracts [82] to 90% in Ajuga integrifolia aqueous leaf extracts [177]. In antimalarial studies against chloroquine-sensitive (D6, 3D7, D10, FCA/GHA, FCR3, K39, and NF54) and chloroquine-resistant (DD2, ENT 30, FCR3, K1, V1/S, and W2) P. falciparum isolates, 49.6% (67/135) were active with the lowest IC50 of 0.16 μg/ml recorded against NF54 isolate for spermine alkaloids in Albizia gummifera [178]. On the other hand, 68 species (50.4%) were inactive. The most active extracts were those of isolated pure compounds. For example, spermine alkaloids: budmunchiamine K, 6-hydroxybudmunchiamine K, 5-normethylbudmunchiamine K, 6-hydroxy-5-normethylbudmunchiamine K, and 9-normethylbudmunchiamine K from Albizia gummifera bark [178] had IC50 of 0.16 μg/ml recorded against ENT30. Curine, isolated from Cissampelos mucronate roots, showed antimalarial activity against W2 isolate with IC50 of 0.24 μg/ml [74]. At present, Artemisia annua [106, 107], Azadirachta indica [108], and Vernonia amygdalina [111] have been subjected to clinical studies. Artemisinin from Artemisia annua is an ingredient of artemisinin-based combination therapy currently recommended for treatment of malaria [124]. As identified earlier, few clinical trials have been done on antimalarial plants. This is partly due to the regulatory requirements for clinical studies, as well as the financial input required.


## 4. Conclusion

Indigenous knowledge on medicinal plants in Kenya is a good resource for malaria management. However, further studies are required to isolate the active compounds in the unstudied plants which can be used to standardize plant materials so as to install a reproducible herbal medicine practice. Safety and toxicity as well as clinical studies are required as some of the plants are used as admixtures in traditional herbal management of malaria.



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*Source: 4538602-2020-06-12.xml*