# Anthelmintic Agents from African Medicinal Plants: Review and Prospects

Authors: Jonathan Jato; Emmanuel Orman; Yaw Duah Boakye; Emelia Oppong Bekoe; Samuel Oppong Bekoe; Samuel Asare-Nkansah; Verena Spiegler; Andreas Hensel; Eva Liebau; Christian Agyare
Journal: Evidence-Based Complementary and Alternative Medicine
 (2022)

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## Abstract

Soil-transmitted helminthiasis affects more than 1.5 billion people globally and largely remains a sanitary problem in Africa. These infections place a huge economic burden on poor countries and affect livestock production, causing substantial economic losses and poor animal health. The emergence of anthelmintic resistance, especially in livestock, and the potential for its widespread in humans create a need for the development of alternative therapies. Medicinal plants play a significant role in the management of parasitic diseases in humans and livestock, especially in Africa. This report reviews anthelmintic studies that have been conducted on medicinal plants growing in Africa and published within the past two decades. A search was made in various electronic databases, and only full articles in English were included in the review. Reports show that aqueous and hydroalcoholic extracts and polar fractions obtained from these crude extracts form the predominant (80%) form of the extracts studied. Medicinal plants, extracts, and compounds with different chemical groups have been studied for their anthelmintic potential. Polyphenols and terpenoids are the most reported groups. More than 64% of the studies employed in vitro assays against parasitic and nonparasitic nematode models. Egg hatch inhibition, larval migration inhibition, and paralysis are the common parameters assessed in vitro. About 72% of in vivo models involved small ruminants, 15% rodents, and 5% chicken. Egg and worm burden are the main factors assessed in vivo. There were no reports on interventions in humans cited within the period under consideration. Also, few reports have investigated the potential of combining plant extracts with common anthelmintic drugs. This review reveals the huge potential of African medicinal plants as sources of anthelmintic agents and the dire need for in-depth clinical studies of extracts, fractions, and compounds from African plants as anthelmintic agents in livestock, companion animals, and humans.


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## Body

## 1. Introduction

Parasitic worms affect more than one-quarter of the world’s population, with soil-transmitted helminthiases (STH) accounting for about 1.5 billion infections [1, 2]. STH is one of the neglected tropical diseases (NTDs) that affects mainly people living in regions of high poverty, without adequate sanitation, and in close contact with infectious vectors, domestic animals, and livestock [2, 3]. They occur globally in the tropics and subtropics, including the Americas, Asia, and sub-Saharan Africa. These areas are more impacted because of the low levels of development [2, 4].Helminth infection is largely a sanitary problem and is associated with the human-animal food chain. Parasite eggs present in human faeces contaminate the soil where they embryonate and are taken back into the intestinal tract through poorly treated drinking water and foods [5]. This creates a vicious cycle of recurrent infections that is often difficult to break or interrupt [3, 6].Although helminthiases have a low fatality rate, they have a huge impact on human health and livestock production. The severity of symptoms in humans depends on the worm burden and whether monospecific or mixed infections are involved [2, 7]. Whilst children constitute the most vulnerable group to worm infestation, pregnant women also suffer impaired immunity and a lower quality of life [5, 8–10].Based on the location of the adult parasite in the body, helminthiases may clinically present as intestinal (whipworms, intestinal roundworms, and hookworms), or tissue (trematodes, hydatid tapeworms, and tissue roundworms) parasites [5, 11]. The most common and widespread intestinal nematodes in humans include Ascaris lumbricoides, Ancylostoma duodenale, Necator americanus, Trichuris trichiura, and Strongyloides stercoralis, which have been classified as soil-transmitted helminthiases [3, 12]. Mild symptoms include abdominal pain, nausea, diarrhoea, and loss of appetite, and in children, severe cases may lead to anaemia, eosinophilia, stunted growth, malnutrition, pneumonia, and poor physical and cognitive development [3, 13]. High-intensity infections could result in intestinal obstruction requiring surgery and death in cases of Strongyloides stercoralis [14].Unlike for some viral and bacterial diseases, there are currently no vaccines developed for human intestinal parasites [5, 15, 16]. In livestock, however, the first vaccine (Barbervax®) against H. contortus, which is derived from an intestinal surface antigen of the nematode, has proven to be a sustainable control measure in small ruminants [17]. Control measures mainly include periodic deworming, health education, and improvements in environmental sanitation. Seasonal chemotherapy with synthetic anthelmintics remains the primary measure to eliminate or reduce infecting helminths. Health education helps to prevent reinfection, while improved sanitary conditions reduce egg transfer to soil [14].Morbidity due to helminthiases has been greatly reduced by the annual or biannual mass drug administration (MDA) in vulnerable populations. The two benzimidazole drugs, mebendazole and albendazole, are the core agents recommended by the World Health Organization (WHO) for MDA in children of school age. Both drugs are effective, cheap, easy to administer, and have been used in large populations for several years with minor side effects [14]. Other classes of anthelmintic drugs available include macrocyclic lactones, imidazothiazoles, tetrahydropyrimidines, and amino-acetonitrile derivatives. Other drugs, including levamisole, pyrantel pamoate, niclosamide, ivermectin, and piperazine, have contributed immensely to tackling livestock and human parasites [18].The increase in cost, availability, continual reinfection, emergence of drug-resistant parasites, adverse events associated with population-wide drug use [9, 17, 19], and lack of coverage for other infectious agents like Strongyloides have become major drawbacks to the success of anthelmintic chemotherapy [20]. These threats have spurred the quest to discover and develop new, innovative, sustainable, effective, safe, alternative, and complementary treatment options, mostly from natural products [21–24].In Africa, about 80% of the population largely depend on traditional remedies for their primary healthcare needs [25–27]. Compared to orthodox medicines, these remedies are relatively accessible and cheaper, perceived to be safe and effective, and form part of folkloric practices [22, 24, 28]. Plants form the larger part of these traditional remedies and have historically been used in treating internal parasites and other diseases in humans and livestock [15, 29, 30]. They constitute a viable source of chemically diverse molecules with broad-spectrum activity and can be a ready means to combat parasite resistance. From January 1981 to September 2019, 71 new approved drugs were entirely derived from natural products, 14 as natural botanicals, and 356 as semisynthetic derivatives of natural molecules [31]. However, there is currently no anthelmintic drug product approved that has been developed from plant sources [18].Even though the chemical constituents and mechanisms by which medicinal plants elicit the observed activities are less known [28, 32], technological advancement has reignited research using in vitro and in vivo assays to evaluate ethnopharmacological claims and, where possible, identify such chemical entities and their mechanisms [22, 28].This review is unique in the sense that it gathers information on anthelmintic extracts, fractions, and compounds from African medicinal plants. It seeks to reveal the potential of African medicinal plants as sources of new anthelmintic molecules and alternative therapies against helminthiases.Whereas the African continent has a huge natural resource pool that is widely used by local people, especially indigenous people, for the management of many disease conditions, the continent remains one of the hardest hits by intestinal parasites [2]. There is increasing research into natural products, especially medicinal plants, as sources of new antiparasitic agents. Despite efforts to gather the library of these plant products, be they extracts, fractions, or purified compounds [7, 23, 33], those available from African medicinal plants are scattered and limited to certain geographical regions. This review, therefore, sought to expand this pool of information and to create a clear picture of the situation as far as studies of anthelmintic agents from African medicinal plants are concerned. Here, we elaborate on the various studies that have been conducted on medicinal plants native to Africa and espoused on the very promising plant families and species.


### 1.1. Methodology

#### 1.1.1. Inclusion and Exclusion Criteria

For the scope of this review, full-text articles published in credible peer-reviewed journals, publishers, and repositories (see below) whose studies focused on the anthelmintic activities of medicinal plants that grow in Africa were included. Only articles written in English and published between January 2002 and December 2021 were included, no matter where the study was conducted.Articles written before 2001 and after 2021 were excluded. Articles that focused on extracts, fractions, and/or compounds isolated from medicinal plants not growing in Africa were also excluded. Even though this review is extensive, it is not a systematic review. The review also significantly focused on gastrointestinal nematode-related studies than other types of helminthiases.


#### 1.1.2. Literature Search and Data Extraction

Articles were identified through literature searches in relevant electronic databases and search engines, including Scopus, Science Direct, Academic Journals, African Journals Online (AJOL), HINARI, BioMed Central, Google Scholar, JSTOR, and PubMed. Bibliographies of included articles were further searched, and pertinent, relevant information retrieved in primary searches was added. This search was conducted between April 2020 and April 2022.Articles that were retrieved were independently screened by at least three authors, and those that met the inclusion criteria were selected for review.Data were often obtained from relevant portions of the articles, including the “materials and methods” and “results” sections. The extraction focused on the botanical source of plant material, the nature of extracts, fractions, or compounds, and the type of assay employed, including in vitro and in vivo studies. The relevant measures of efficacy in the test system, including IC50, EC50, LC50, and LD50, were used to assess the anthelmintic potential of the study samples. Mendeley Desktop (version 1.19.4, copyright 2008–2020, Mendeley Ltd.) was used to manage the citations.The botanical identities of plants and their habitats in Africa were verified against information fromhttps://www.worldfloraonline.org/search (formerly https://www.theplantlist.org) and https://plants.jstor.org/plants/browse.


## 1.1. Methodology

### 1.1.1. Inclusion and Exclusion Criteria

For the scope of this review, full-text articles published in credible peer-reviewed journals, publishers, and repositories (see below) whose studies focused on the anthelmintic activities of medicinal plants that grow in Africa were included. Only articles written in English and published between January 2002 and December 2021 were included, no matter where the study was conducted.Articles written before 2001 and after 2021 were excluded. Articles that focused on extracts, fractions, and/or compounds isolated from medicinal plants not growing in Africa were also excluded. Even though this review is extensive, it is not a systematic review. The review also significantly focused on gastrointestinal nematode-related studies than other types of helminthiases.


### 1.1.2. Literature Search and Data Extraction

Articles were identified through literature searches in relevant electronic databases and search engines, including Scopus, Science Direct, Academic Journals, African Journals Online (AJOL), HINARI, BioMed Central, Google Scholar, JSTOR, and PubMed. Bibliographies of included articles were further searched, and pertinent, relevant information retrieved in primary searches was added. This search was conducted between April 2020 and April 2022.Articles that were retrieved were independently screened by at least three authors, and those that met the inclusion criteria were selected for review.Data were often obtained from relevant portions of the articles, including the “materials and methods” and “results” sections. The extraction focused on the botanical source of plant material, the nature of extracts, fractions, or compounds, and the type of assay employed, including in vitro and in vivo studies. The relevant measures of efficacy in the test system, including IC50, EC50, LC50, and LD50, were used to assess the anthelmintic potential of the study samples. Mendeley Desktop (version 1.19.4, copyright 2008–2020, Mendeley Ltd.) was used to manage the citations.The botanical identities of plants and their habitats in Africa were verified against information fromhttps://www.worldfloraonline.org/search (formerly https://www.theplantlist.org) and https://plants.jstor.org/plants/browse.


## 1.1.1. Inclusion and Exclusion Criteria

For the scope of this review, full-text articles published in credible peer-reviewed journals, publishers, and repositories (see below) whose studies focused on the anthelmintic activities of medicinal plants that grow in Africa were included. Only articles written in English and published between January 2002 and December 2021 were included, no matter where the study was conducted.Articles written before 2001 and after 2021 were excluded. Articles that focused on extracts, fractions, and/or compounds isolated from medicinal plants not growing in Africa were also excluded. Even though this review is extensive, it is not a systematic review. The review also significantly focused on gastrointestinal nematode-related studies than other types of helminthiases.


## 1.1.2. Literature Search and Data Extraction

Articles were identified through literature searches in relevant electronic databases and search engines, including Scopus, Science Direct, Academic Journals, African Journals Online (AJOL), HINARI, BioMed Central, Google Scholar, JSTOR, and PubMed. Bibliographies of included articles were further searched, and pertinent, relevant information retrieved in primary searches was added. This search was conducted between April 2020 and April 2022.Articles that were retrieved were independently screened by at least three authors, and those that met the inclusion criteria were selected for review.Data were often obtained from relevant portions of the articles, including the “materials and methods” and “results” sections. The extraction focused on the botanical source of plant material, the nature of extracts, fractions, or compounds, and the type of assay employed, including in vitro and in vivo studies. The relevant measures of efficacy in the test system, including IC50, EC50, LC50, and LD50, were used to assess the anthelmintic potential of the study samples. Mendeley Desktop (version 1.19.4, copyright 2008–2020, Mendeley Ltd.) was used to manage the citations.The botanical identities of plants and their habitats in Africa were verified against information fromhttps://www.worldfloraonline.org/search (formerly https://www.theplantlist.org) and https://plants.jstor.org/plants/browse.


## 2. Anthelmintic Resistance in Humans and Livestock

Parasite susceptibility to the existing anthelmintic drugs continues to rapidly decline, leading to the emergence of drug-resistant parasites. Several studies have reported the development and spread of resistance to all major classes of anthelmintics [34–36], especially in livestock and, to a lesser extent, in companion animals and humans [9, 37]. The main contributing factors to drug resistance include selective pressure induced by high treatment frequencies, single-drug regimens, preventive mass treatments, inadequate dosing, indiscriminate use, and overreliance on synthetic drugs to control helminthiases [18, 34, 38].High-frequency preventive chemotherapy in humans and livestock, as a result of the high disease burden and limited number of anthelmintics, causes a reduction in worm refugia-enhancing mutations and resistance development [5, 21, 39]. Prolonged use of single drugs, for example, the use of ivermectin for Onchocerciasis control in West Africa and praziquantel against Schistosomiasis in Egypt, has been associated with widespread resistance [34].The development and spread of drug-resistant traits at the molecular level have been well investigated in the model organismC. elegans [40] and the barber’s pole worm (H. contortus) [41]. Mutations in genes coding for drug receptor sites or the expression of genes involved in drug efflux, detoxification, or amphidial drug uptake have for instance been reported as possible causes of drug resistance [42, 43]. Resistance to the benzimidazoles in trichostrongylid nematodes in ruminants has been ascribed to mutations in the isotype 1 β-tubulin gene (E198A, E198L, F167Y, and F200Y) [44–46].Nematodes, generally upon hatching, undergo multiple larval developmental stages into adult worms [5], and this multistage cycle poses a challenge to drugs that target just a few stages. Broad-spectrum activity against egg hatching, larval metamorphosis, and adult worms is therefore an ideal requirement for anthelmintic agents [7].The use of plant extracts may significantly delay and reduce the spread of resistance among parasite populations [47, 48]. These multicomponent systems with natural products from very different classes could interact with multiple developmental stages, help reduce natural selection pressures, and delay resistance development, which are typically found in such multitarget systems [49–51]. Selective treatment of individuals, multidrug therapy, and environmental parasite control strategies slow down the emergence of selective resistance alleles [38].


## 3. Anthelmintic Drug Development from Natural Products: Prospects and Challenges

Since the beginning of the use of modern anthelmintics era in the 1950s, only a handful of such drugs are available for use in humans [52]. The rate of anthelmintic drug development by the pharmaceutical industry has nosedived over the past four decades, partly due to high costs and low returns from investments in this area [16, 53–55]. Following the successful introduction of ivermectin in 1987 against onchocerciasis in humans [56], two other agents, namely emodepside and tribendimidine, are well advanced in human clinical trials against this disease [5, 57, 58]. On the other hand, monepantel, emodepside, and derquantel have recently been approved for use in livestock [16].Natural products, including those from plants, animals, fungi, marine organisms, and bacteria, have been acclaimed as the panacea to synthetic drug discovery challenges [54, 59]. Many studies end with the evaluation of plant extracts, fractions, and some isolated compounds for anthelmintic activities [50], with no plant-derived compound currently in use as an anthelmintic drug in humans [18]. Pyrethrum, nicotine, and rotenone are some drug products of plant origin that have been used as antiparasitic agents in veterinary practice [60].The discovery and development of anthelmintic agents from natural sources and the isolation and characterization of bioactive constituents have therefore become the end goal of research in this less-funded area [7, 60]. Whereas several efforts have been made towards the isolation and characterization of antiparasitic compounds from plant sources in the past two decades, little is seen in other organisms such as bacteria and fungi [7]. The disadvantage of the isolation approach, however, is the unavoidable loss of so-called pharmacological synergy or toxicological antagonism associated with multicomponent extracts and fractions [7].Issues of availability of bioactive minor compounds from the plant material in sufficient amounts, stability, formulation, delivery, compatibility, and many years of development have also kept some promising plant molecules out of the market. Because of their bulky nature, semisynthetic measures to modify the chemical structures and properties of plant molecules have proven difficult and expensive [60].Generally, medicinal plants have not competed favourably with orthodox medicines as anthelmintics. The expensive human clinical efficacy and safety trials and bureaucratic licensing procedures, accompanied by a limited drug market, disincentivize the pharmaceutical industry from plant-based anthelmintic product development. The yield and nature of phytoconstituents are also variedly influenced by environmental factors like climate, altitude, soil type, rainfall, and herbivore predation. This erratic and unpredictable outcome affects the establishment of consistent quality control measures and hence reduces the interest of pharmaceutical investors [7].Proprietary issues of ownership, royalties, access, government charges, and patency for plant-based drugs further deflate the hopes of drug-producing companies, which have high expectations for investment returns [60]. The presence of “pan assay interference compounds,” often referred to as “PAINS,” is militating against the advancement of preliminary bioassays on plant extracts. PAINS is an unorganised group of promiscuous molecules that occur as unspecific hits in several enzyme assays and in vitro screenings. These subversive compounds have often been considered for optimisation steps but end up consuming a lot of resources of investigators [61]. The presence of these molecules in high-throughput screens, on the other hand, should be recognised as a cautious group requiring further assessment rather than an outright rejection as irrelevant [62].Contrary to the popular notion, not all natural compounds are innocuous [7]. Often produced as defence mechanisms or in response to external stress, some natural products from plants are potentially toxic to humans and animals and can be deleterious to physiological functions [63, 64]. An investigation by Ali et al. [65], for instance, revealed that even though the crude saponins from aerial parts of Achillea wilhelmsii and Teucrium stocksianum have significant anthelmintic activities, they were cytotoxic in the brine shrimp assay. This, therefore, implies that any anthelmintic hit from plant extracts must be verified for its safety in mammalian cells [66] and, if possible, in living organisms.With the emergence and rapid spread of multidrug resistance to existing synthetic anthelmintics, the prospects for drug development from natural sources remain high [67]. To attract investors, herbal anthelmintics must be developed to a stage where rigorous and reproducible quality control can be assured. Standardized extracts have a huge market potential due to the current drive for organic food supplements [60]. Multicomponent plant extracts may potentiate efficacy, counter toxicity, enhance bioavailability, or improve the stability of each other in formulations [68–71].A more interesting addition to the herbal industry is the advancement in the genetic engineering of specific metabolic pathways [72]. Genetic modification and tissue cultures can increase the yield of target molecules and improve the turnover rate [59]. This also counters the risk of plant depletion through wild harvesting and reduces the impact of an unfavourable climate on raw materials [72].


## 4. Brief Comparison of In Vitro and In Vivo Anthelmintic Assays

Preliminary screening of natural products for pharmacological activities requires the use of validated methods to guarantee reproducible outcomes [73]. Since helminth infections are complex and often involve mixed parasites with varied lifecycles, models for testing for antiparasitic activities also widely differ between species. These investigations are grouped into the in vitro and in vivo techniques [74].Most primary investigations of plant materials for anthelmintic activity employ in vitro bioassays [22, 74–76], which rapidly screen large numbers of samples, are simple in design, easy to perform, cheap to implement, require minimal ethical considerations, require a small quantity of samples, and quickly churn out reproducible results [49, 75, 77, 78]. These assays target various stages of the parasite lifecycle, including egg laying or hatching, larval development, migration, motility, motor paralysis, and lethality [5, 79]. The current gold standard for assessing the susceptibility of adult and larval worms to drugs is in vitro worm motility assays using read out by microscopy [53]. Some in vitro assays use nonparasitic worm models, whereas others involve the isolation of eggs or larvae from experimentally or naturally infected animal hosts and the growth of larvae in vitro, during which periods the test substances can be applied and activity evaluated [80].The results of basic in vitro assays of test samples (“hits”) are confirmed by the higher test models, which are specialized in vitro and in vivo studies to define possible “lead” status [78]. It is however often difficult to reproducibly extrapolate results from in vitro investigations to in vivo activity owing to pharmacokinetics issues [81]. The growth and maintenance of parasitic nematodes for long periods outside the host is often a laborious, expensive, and slow process that hinders effective in vitro studies [82]. The versatility, availability, ease of culture maintenance, and high proliferation rate make C. elegans, a free-living, nonparasitic nematode, a suitable model for many nematocidal and mechanistic studies [40, 76, 82].In vivo assays involve the use of whole animals and are models that remain close to the patient, which is the final target for drug development [73]. Studies involve the in vivo investigation of anthelmintic potential using animals infected with the relevant parasites. The outcomes of in vivo studies are influenced by the mode of administration, nature, and dose of the test substance, host organism, and parasite species involved. Faecal worm, egg count, worm shedding, and host immune response are usually the parameters evaluated. Egg counts evaluate the effect of treatment on adult parasite fecundity, whereas parasite load depicts the effect on larvae or adult worms. The density-dependent fecundity effect, however, limits the significance of the FECR assay [49, 53] and cannot be used for Strongyloides spp., whose eggs are not passed in stool but larvae.Although in vivo studies provide superior and reliable outcomes for pharmacological screening due to the natural, biological, pharmacological, pharmacokinetic, and toxicological environments, they are expensive, slow for large-scale investigations, labour-intensive, and often bedevilled with ethical and animal welfare issues [73, 75].


## 5. General Overview of Anthelmintic Evaluation of African Medicinal Plants

From this review, it is evident that African medicinal plants have great potential as sources of anthelmintic agents. An ideal anthelmintic agent should have broad spectrum activity, affecting almost all stages of the lifecycle of the nematodes and sufficient safety. Whereas some studies that considered more than one parasite stage reported such broad spectrum activities, a few others reported disparities in efficacy against various forms of the parasites [83–85].The majority (78%) of the studies or reports reviewed employed in vitro assays in evaluating the anthelmintic activities of medicinal plants. In vitro models mainly focused on the ability of drug candidates to inhibit egg hatching, larval migration, motility, larval development or exsheathment, and survival [86–94].The in vitro test models involve parasitic nematodes such asHaemonchus contortus, Ancylostoma caninum, Ascaris suum, Heligmosomoides bakeri, Heligmosomoides polygyrus, Trichostrongylus axei, Strongyloides papillosus, Trichuris ovis, Oesophagostomum columbianum, and Oesophagostomum venulosum [95–97]. Nonparasitic earthworms, including Pheretima posthuma, Lumbricus terrestris, Eisenia fetida, and Eudrilus eugeniae, have also been used as in vitro models for studying the anthelmintic effects of many extracts [98–103], cited in [104]. The free-living nematode, C. elegans, continues to remain the most widely used non-parasitic test model for in vitro anthelmintic studies [105–110].H. contortus and related gastrointestinal nematodes (GIN) of small ruminants are the most widely investigated organisms in in vivo models, whereas sheep and goats are the major animals in which such clinical investigations have been reported [86, 87, 111, 112]. There are few reports involving trials in pigs, chickens, goldfish, snails, rats, and mice [113–117]. The ability of test substances to reduce faecal egg count (FEC), a typical measure of effects on fecundity, and postmortem intestinal worm burden are the parameters measured in in vivo assays. A few other studies evaluated the physiological impact of test substances on haematological indices of host animals in addition to the antiparasitic investigations [95, 111, 116, 118–120]. There was no report cited that investigated the clinical efficacy of extracts or isolated compounds in human subjects, neither was any activity testing reported on commercially available herbal anthelmintic products from these medicinal plants. There is, therefore, is a need to clinically evaluate some of these plant products and establish quality parameters for their development into standardised remedies for helminthiases.The anthelmintic activities reported vary widely depending on the plant species, type of extract, strain of nematode, and its parasitic stage of development. A similar observation was reported in a review of anthelmintic agents used in goats [74]. Most in vivo studies, however, produced lower efficacies compared to their in vitro counterparts regarding the same plant samples [74]. The effects of pharmacokinetic processes such as absorption and metabolism and the biological variations of host animals could be accountable for these observations [75]. Also, many of the studies report activity lower than that observed for the standard anthelmintic drugs often used as positive controls [121–124]. An in vitro study of Carica papaya extracts against the Indian earthworm P. posthuma, however, was reported to show better paralytic (p<0.0001) and wormicidal (p<0.0001) activity than albendazole [6].Almost 80% of the studies evaluated aqueous or hydroalcoholic extracts evaluated aqueous or hydroalcoholic extracts of various plant materials including root barks, stem barks, flowers, seeds, and whole plants, oils, and latex or exudates (Table1). A few organic extracts, fractions, and crude powdered plant materials (mostly as feed) have also been studied [65, 84, 112, 169, 172, 197]. This trend is expected since many studies seek to replicate traditional applications of the study materials.Table 1
African medicinal plants with anthelmintic activities, sorted according to the respective plant families.
No.Nature of extractBotanical sourceHabitat in AfricaAssay(s) conductedOutcome of assay(s)Acanthaceae(1)Aqueous extractLeaves ofAcanthus montanus (Nees) T. AndersWest and East AfricaIn vitro EHIA, and larval growth inhibition assay against strongylid nematodes of sheep and goats91.75% reduction in egg hatch and 67.02% larval inhibition at 25 mg/ml in 24 h [90](2)1 : 1 DCM: methanolic extractRoots and leaves ofLinariantha bicolor B. L. Burtt & R. M. Sm.Tropical AfricaIn vitro activity againstL3, L4 and adult C. elegans (wild type, Bristol N2)Root extract significantly reduced survival of young adult worms to 57% [107]Amaranthaceae(3)Ethanolic extractLeaves ofAmaranthus spinosus L.West AfricaIn vivo FEC assay againstAscaris suum, Hyostrongylus rubidus and Trichuris trichiura in pigsMore than 80% reduction of FEC on day 7 posttreatment with 0.5 g/kg [125](4)Ethanolic extractIn vitro activity against GIN from goats60% mortality at 100 mg/mL [126](5)Aqueous and methanolic extractsWhole plant ofChenopodium album L.East AfricaIn vitro antimotility, and EHIA againstH. contortus and in vivo against FEC in mixed parasite infected sheepLC50 = 0.134 mg/mL against egg hatching and significantly reduced FEC (93.9% at 3.0 g/kg on day 13 posttreatment [127]Anacardiaceae(6)Acetone extract and fractionsLeaves ofAnacardium occidentale L.West Tropical AfricaIn vitro EHIA and larval development and viability assays againstH. contortusLC50 of acetone extract was 0.31 and 1.72 mg/ml for hatchability and larval viability test, respectively [122](7)Ethanolic extractsMangifera indica L.Tropical AfricaIn vitro activity against GIN from goatsExtract induced 50% mortality at 100 mg/mL [126](8)Aqueous extractLeaves, stem, and root barks ofSpondias mombin L.Tropical AfricaParalysis and death time in vitro assay against earthwormE. eugeniaeLeaf extract caused paralysis and death at 15 ± 0.33 and 34 ± 0.65 min, respectively [128](9)n-Hexane, acetone, and aqueous extractsLeaves ofSpondias mombin L.In vitro activity against adultHaemonchus placeiAll extracts show some level of activity against the worms with LC50 values of 104, 30.5 and 56.27 mg/mL, respectively [129]Annonaceae(10)Aqueous extractLeaves ofAnnona muricata L.West AfricaIn vitro EHIA, and larval mortality assay againstH. contortusEffective against egg hatching,L3 larvae (84.91%) and adult worms and 89.08% inhibition at 33% v/v [130](11)Aqueous extractsStem bark ofAnnona senegalensis Pers.Tropical AfricaIn vitro faecal egg hatch inhibition activity againstH. contortus in sheepConcentration-dependent decline in larval recovery (88.5 ± 3.1% at 7.1 mg/ml) [131](12)Aqueous extractSeeds ofMonodora tenuifolia Benth.West and East AfricaIn vitro EHIA against mixed intestinal nematodes of goatsSignificant reduction in egg hatching (93%) at 100  mg/ml [87](13)Ethanolic extractLeaves and stem bark ofPolyalthia longifolia (Sonn.)West AfricaIn vitro larval mortality and in vivo FEC assays against H. bakeri in miceBoth extracts possess inhibitory effects on larvae and FEC. At 400  mg/kg the extracts reduced FEC to 0.60 ±  0.24 and 0.40 ±  0.24 EPG, respectively [132](14)Methanolic extractsSeeds and leaves ofXylopia aethiopica A. RichTropical AfricaIn vivo assay of postmortem worm recovery againstNippostrongylus brasiliensis in ratsExtract produced about 76% deparasitisation [133](15)Ethanolic extractsFruits and leaves ofXylopia aethiopica A. Rich.In vitro activity againstP. posthumaAt 30  mg/ml, the fruit extract caused paralysis and death in 65.34 ± 7.05 and 81.72 ± 19.63 min, respectively, whilst leaf extract caused same effects in 69.27 ± 0.00 and 96.39 ± 0.00 min, respectively [134]Apocynaceae(16)Hydroethanolic extractStem and root barks ofAlstonia boonei De WildTropical West and East AfricaIn vitro assay againstP. PosthumaBoth extracts induced significant paralysis (17.00 ± 2.10 and 93.00 ± 2.04 min) and death (100.00 ± 2.47 and 151.00 ± 2.27 min), respectively [135](17)Aqueous and ethanolic extractsStem bark ofAlstonia boonei De WildIn vitro paralysis and mortality assay against earth worms-Lumbricus terretrisBoth extracts induced paralysis (43.50 ± 7.67 and 34.89 ± 2.48 min, respectively) [99](18)Crude powder, aqueous and methanolic extractsFlowers ofCalotropis procera Ait. F.Tropical AfricaIn vitro assay against adult motility, and in vivo FEC againstH. contortus in sheepPowder and aqueous extract reduced FEC (88.4 and 77.8% at 3 g/kg on day 7 and 10 posttreatment, respectively). Aqueous extract induced 70% worm paralysis at 6 h of 25 mg/ml treatment [121](19)Dried and fresh latexLatex ofCalotropis procera Ait. F.In vitro activity against adultP. posthumaLatex possess wormicidal activity (100% mortality at 60 min of 100 mg/ml treatment) and caused causing irreversible paralysis in lower doses [136](20)Methanolic extractsStem bark and leaves ofRauvolfia vomitoria Afzel.Tropical AfricaIn vitro activity againstP. posthumaAt 50 mg/ml, the two extracts caused paralysis at 11.17 ± 0.08 and 21.68 ± 0.10 min and death at 21.67 ± 0.73 and 143.35 ± 1.41 min, respectively [137](21)Methanolic extractsStem bark and leaves of Voacanga africana Stapf ex. Scott-ElliotTropical AfricaIn vitro activity againstP. posthumaAt 50 mg/ml, both extracts caused paralysis at 7.03 ± 0.49 and 22.55 ± 0.57 min and death at 14.77 ± 0.12 and 113.99 ± 1.01 min, respectively [137]Asparagaceae(22)Aqueous extractSisal waste liquid ofAgave sisalana Perrine ex Engelm.West Tropical AfricaIn vivo FEC assay, coprocultures and postmortem worm counts in goatsExtracts reduced FEC (50.3%) and faecal worm count (80%) at 1.7 g/kg with no apparent toxicity to the animals [119](23)Aqueous extractsLeaf, scape, and bulb ofDrimia indica (Roxb.) Jessop.East and West AfricaIn vitro action against adultP. posthumaAll extracts had significant anthelmintic effects. The hot aqueous extract of the leaf was the most active, inducing paralysis at 41.3 ± 0.94 min and death at 50 ± 0.81 at 5 mg/ml [104]Asteraceae(24)Saponin fractionAerial parts ofAchillea wilhelmsii K. KochNorth AfricaIn vitro assay onP. posthuma, tapeworms (R. spiralis), and adult roundworms (A. galli)At 40 mg/ml,A. wilhelmsi fraction was 1.96 and 2.12 times more potent than albendazole against P. posthuma and R. spiralis, respectively [65](25)Aqueous extractLeafy stems ofAgeratum conyzoides L.Tropical AfricaIn vitro effects on adultL. terrestrisExtract caused 100% mortality at 62 ± 0.28 min [138](26)Aqueous and ethanolic extractsAerial parts ofArtemisia absinthium L.North AfricaIn vitro worm motility assay againstH. contortus and in vivo FEC in sheep nematodesBoth extracts were active against ovine nematodes. Ethanolic extract caused FECR of 90.46% at 2.0 g/kg on day 15 posttreatment, and >80% inhibition of worm motility in vitro after 8 h with 25 mg/ml treatment [139](27)Aqueous and methanolic extractsWhole plant ofArtemisia brevifolia Wall.South and Tropical AfricaIn vitro inhibition of adult worm motility against H.contortus and in vivo FEC assay against H. contortus, T. colubriformis, T. axei, O. columbianum, S. Papillosus and T. ovis in sheepMethanolic extract inhibited motility (80% at 6 h with 25 mg/ml treatment) and aqueous extract reduced FEC in vivo (67.2% at 3 g/kg on day 14) [140](28)Aqueous and ethanolic extractsLeaves ofVernonia amygdalina Del.Tropical AfricaIn vitro paralysis and mortality assay against earth worms-Lumbricus terretrisBoth extracts caused significant paralysis (59.94 ± 8.25 and 33.18 ± 12.41 min, respectively) [99](29)Aqueous extractIn vitro faecal egg hatch inhibition activity againstH. contortus in sheepExtract had no significant inhibition at 11.2 mg/ml [131](30)Acetone extractIn vitro testing on eggs, infective larvae, and adult stages ofH. contortusExtract was active with 42% ovicidal effect, 70% inhibition of larval migration 90% adulticidal effects at 300μg/mL [141](31)Chloroformic and ethanolic extractsStem ofVernonia amygdalina Del.In vitro activity against adultP. posthumaChloroformic extract was more active causing paralysis and death at 11.95 ± 0.28 and 41.74 ± 2.21 min, respectively, at 75 mg/ml [142]Burseraceae(32)Aqueous extractsLeaves, stem, and root barks ofCommiphora africana A. Rich, Engl.Tropical AfricaParalysis and death time in vitro assay against earthwormE. eugeniaeLeaf extract induced paralysis and death at 17 ± 0.72 and 87 ± 6.89 min, respectively [128](33)Aqueous and methanolic extractsStem bark ofBoswellia dalzielii Hutch.West AfricaIn vitro assay against egg hatching ofC. elegans strainsBoth extracts, respectively, yield 53.8% and 69.1% egg hatch inhibition at 2 mg/ml [106]Combretaceae(34)Aqueous extractLeaves ofAnogeissus leiocarpus (DC.) Guill. & Perr.West, Central and East AfricaIn vivo effects on FEC in sheep naturally infected with gastrointestinal nematodesDose-dependent FECR and worm burden reduction (39.5% and 33%, respectively, after 3 consecutive days 400 mg/kg treatment) [143](35)Aqueous decoctionIn vitro EHIA, larvicidal assay and mortality of adultH. contortusSignificant ovicidal (ED50 = 409.5 μg/mL), and larvicidal (100% eclodibility inhibition at 1.2 mg/ml) actions. Active against adult worms, but not dose dependent [89](36)Acetone extract and fractionsIn vitro EHIA and larval viability assays againstH. contortusThe extract and fractions exhibited concentration-dependent ovicidal and larvicidal activity. LC50 of 360 and 509 μg/ml, respectively, for the acetone extract [92](37)Aqueous and ethanolic extractsLeaves and bark ofAnogeissus leocarpus (DC.) Guill. & Perr.In vitro activity againstC. elegans (wild type) larvaeEthanolic extract of the bark was the most active with LC50 of 380 μg/ml [144](38)Methanolic and chloromethylenic extractsLeaves, roots, and bark ofAnogeissus leocarpus (DC.) Guill. & Perr.In vitro activity againstRhabditis pseudoelongataAll extracts possess anthelmintic action with EC50 between 2.5 μg/ml and 10 μg/ml [145](39)Fractions of ethanolic extractStem bark ofAnogeissus schimperi Hochst.Tropical AfricaIn vivo activity againstNippostrongylus braziliensis in rats.Aqueous fraction showed 64.15% efficacy at 50 mg/kg body weight [146](40)Acetone extract and fractionsLeaves ofCombretum molle R. Br. ex G. DonTropical East AfricaIn vitro EHIA, larval development, and viability assay inH. contortusExtract and fractions exhibited ovicidal (LC50 = 0.87 mg/ml) and larvicidal (LC50 = 0.60 mg/ml) action against H. contortus [147](41)Ethanolic extractsLeaves ofCombretum mucronatum Schumach. & Thonn.Tropical AfricaIn vitro adulticidal and larvicidal action againstA. ceylanicum, H. bakeri, and T. muris and in vivo against these parasites in NMRI miceExtract possess nematicidal activities with in vitro minimum lethal concentration of 10μg/mL against T. muris and a worm burden reduction of 85.3% in vivo [148](42)Hydroethanolic extractIn vitro action againstC. elegans larvaeExtract caused 41.9% inhibition of larvae at 1 mg/ml [149](43)Hydroethanolic extract and fractionsIn vitro action againstC. elegans L4 larvae.Extract exhibited moderate activity with LC50 of 1.67 mg/ml. Ethyl acetate fraction was active with LC50 of 1.73 mg/ml [150]Atomic force microscopy ofC. elegans treated with tannin-enriched extract.Ultrastructural changes were reported in the cuticle but no morphological changes on the intestines [151](44)Aqueous and methanolic extractsStem barkGuiera senegalensis J. F. Gmel.Tropical AfricaIn vitro EHIA and larval development ofC. elegans (wildtype and ivermectin-resistant DA1316) strainsMethanolic extract inhibited egg hatch (>80%) and larval development (>90%) in both strains [152](45)Pet. ether, DCM, ethyl acetate, methanolic and aqueous extractsDry fallen leaves ofTerminalia catappa L.Tropical West AfricaIn vitro EHIA and larval mortality assay againstH. contortus98.9% inhibition of egg hatching and 98.9% larval reduction by DCM extract at 6.25 mg/ml [153](46)Methanolic and chloromethylenic extractsLeaves ofTerminalia glaucescens Planch. ex Benth.Tropical AfricaIn vitro activity againstRhabditis pseudoelongataBoth extracts with active with EC50 of 2.5 μg/ml each [145]Cucurbitaceae(47)Aqueous and methanolic extractsSeeds ofCitrullus lanatus (Thunb.) Mansf.East and South AfricaIn vitro paralysis and mortality effects againstL. terrestrisAqueous extract at 50 mg/ml induced paralysis and death at 38.49 ± 1.20 and 58.2 ± 3.41 min, respectively [154](48)Aqueous and methanolic extractsSeeds ofCucurbita pepo L.West AfricaIn vitro paralysis and mortality effects againstL. terrestrisAqueous extract caused concentration-dependent paralysis and death of the worms (37.25 ± 1.60 and 50.49 ± 2.28 min, respectively) at 50 mg/ml [154].(49)Ethanolic extractsLeaves ofMomordica charantia L.Tropical AfricaIn vitro action against adultC. elegans (wild type, N2, Bristol)Extracts of plants from different ecological zones showed varying degree of activities with LC50 between 473 and 997 μg/ml [155].(50)Ethanolic extractsFruits ofMomordica charantia L.In vitro activity against GIN and in vivo FECR assay in goats100% mortality at 100 mg/ml and 78% FECR on day 9 posttreatment [126](51)Aqueous and methanolic extractsSeeds ofTelfairia occidentalis Hook. f.Tropical AfricaIn vitro paralysis and mortality effects againstL. terrestrisAqueous extract at 50 mg/ml caused paralysis and death in 42.97 ± 1.45 and 66.63 ± 4.10 min, respectively [154]Euphorbiaceae(52)Petroleum ether, chloroform, and methanol extractsLeaves ofAlchornea cordifolia (Schumach.) Müll. Arg.Tropical AfricaIn vitro activity againstE. eugeniae (earthworms)The methanol extract was the most active inducing paralysis and death at 26.28 ± 0.575 and 57.30 ± 0.370 min, respectively, at 12 mg/ml concentration [156](53)Methanolic and chloromethylenic extractsIn vitro activity againstRhabditis pseudoelongataThe chloromethylenic extract and alkaloidal fraction significantly inhibited the worms with EC50 of 2.5 μg/ml [145](54)Aqueous and ethanolic extractsLeaves ofEuphorbia hirta L.Tropical AfricaIn vitro activity againstC. elegans (wild type) larvaeEthanolic extract was the most active with LC50 of 2.0 mg/ml [144](55)Methanolic and chloromethylenic extractsLeaves ofMallotus oppositifolius Müll. Arg.West AfricaIn vitro activity againstRhabditis pseudoelongataBoth extracts and alkaloid fraction were active with EC50 of 2.5 μg/ml against the worms [145]Fabaceae(56)Methanolic extractFruits ofAcacia nilotica (L.) Del.Tropical AfricaIn vitro EHIA, adult motility, and larval development assay againstH. contortus and in vivo against H. contortus, T. circumcincta, and T. ovis in sheep.LC50 = 512.86 and 194.98 μg/mL against egg hatch and larval development, respectively. FEC reduced by 78.5% on day 13 post 3.0 g/kg treatment [97](57)Hydroalcoholic extractsIn vitro larvicidal action againstC. elegans strains and Onchocerca ochengiLC50 = 10.8 ±  0.3 μg/mL against microfilariae of O. onchengi and 350 ± 1.1 μg/mL against C. elegans WT [110](58)Dry feed (browse meal)Leaves ofAcacia polyacantha Wild.Ethiopia, South AfricaIn vivo effect on FEC and worm burdens in experimentally infected sheep and goatsModerate reduction in FEC and worm burden: 27% and 13%, respectively, in sheep and 19% FEC reduction in goats [112](59)Acetone extracts of indigenous browsesLeaves ofAcacia senegal (L.) Willd.Tropical AfricaIn vitro EHIA, LMIA and adult motility inhibition assays (AMIA) againstH. contortusEffective against egg hatching (38% at 300μg/mL), with no dose-dependent inhibition of larvae and adults [141](60)Acetone extracts of indigenous browsesLeaves ofAcacia seyal Del.Tropical AfricaIn vitro EHIA, LMIA and AMIA againstH. contortusConcentration-dependent ovicidal effects (34% at 300μg/mL) with minimal effects on larvae and adult worms [141](61)Acetone extracts of indigenous browsesLeaves ofAcacia tortilis (Forssk.) HayneTropical AfricaIn vitro EHIA, LMIA and AMIA againstH. contortusConcentration-dependent ovicidal effects (39% at 300μg/mL) but no significant larvicidal and adulticidal activity [141](62)Methanolic and chloromethylenic extractsLeaves ofAfrormosia laxiflora (Benth. ex Baker) HarmsWest AfricaIn vitro activity againstRhabditis pseudoelongataBoth extracts and alkaloid fraction were active with EC50 of 2.5 μg/ml against the worms [145](63)Ethanolic extractStem bark ofAfzelia africana Sm.West, Central and East AfricaIn vitro EHIA againstH. contortusAbout 90.9% egg hatch inhibition at 5 mg/ml [88](64)Aqueous, methanolic, and chloroformic extractsRoot bark ofAlbizia anthelmintica Brongn.Southern AfricaIn vitro EHIA and larvicidal activity against strongyle-type sheep nematodeThe aqueous extract inhibited egg hatching, larval development, and survival of worms (ED50 = 144.2, 65.2 and 312.4 μg/mL, respectively). The methanolic extract only caused high mortality of larvae (ED50 = 11.8 μg/mL). The chloroformic extract had moderate effects on larval development (ED50 = 208.0 μg/mL) [86](65)Aqueous extractIn vivo efficacy againstHaemonchus spp., Trichostrogylus spp. and Oesophagostomum spp. mixed infection in sheepEfficacy of 89.8% was observed against the nematodes [157](66)Aqueous and ethanolic extractStem bark ofAlbizia schimperiana Oliv.Tropical AfricaIn vitro ovicidal and larvicidal activity againstH. contortusOvicidal activities with ED50 = 0.11 μg/mL of aqueous extract and significantly inhibited larval development (99.31% at 50 mg/ml) [158](67)Methanolic extractSeeds, leaves, flowers ofButea monosperma (Lam.) KuntzeWest Tropical AfricaIn vitro assay againstC. elegans (wild type) larvaeExtract of seeds very active againstC. elegans (ED50 = 901.5 μg/mL) in microwell assay [109](68)Aqueous and methanolic extractsSeed kernel ofCaesalpinia crista L.Tropical AfricaIn vitro antimotility, and EHIA againstH. contortus and in vivo against FEC in mixed parasite infected sheepLC50 = 0.449 mg/ml in egg hatch test. EPG reduced by 82.2% at dose of 3.0 g/kg on day 5 posttreatment [127](69)Aqueous decoctionStem bark ofDaniellia oliveri (Rolfe) Hutch. & Dalz.Sudan, Senegal, Egypt, UgandaIn vitro EHIA, larvicidal assay and mortality of adultH. contortusOvicidal (ED50 = 245.9 μg/mL and larvicidal (100% eclodibility inhibition at 1.2 mg/ml) actions. Active against adult worms, but not dose-dependent [89]70)Acetone extracts of indigenous browsesLeaves ofMillettia ferruginea (Hochst.) ex. BakerTropical AfricaIn vitro testing on eggs, infective larvae, and adult stages ofH. contortusOvicidal action (35% at 300μg/mL) but no significant effects against larvae and adult worms [141](71)Aqueous methanolic extractLeaves ofMimosa pudica L.East AfricaIn vitro egg hatch assay and in vivo usingH. bakeri experimentally infected adult albino miceExtract significantly inhibited egg hatch in vitro (LC50 of 1.160 μg/mL) and reduced worm count in vivo [118](72)Aqueous and ethanolic extractLeaves ofSenna occidentalis (L.) LinkTropical AfricaIn vitro ovicidal and larvicidal activity againstH. contortusED50 = 0.13 μg/mL against egg hatch and 96.36% inhibition of larval development [158](73)Chloroformic and methanolic extractsAerial parts ofTephrosia spinosa (L.f.) Pers.Tropical AfricaIn vitro anthelmintic activity on adult Indian earth worms (Pheretima posthuma)Significant paralytic effect on worms. Chloroformic extract (14.34 ± 0.04 min), methanolic extract (21.98 ± 0.15 min) [98](74)Aqueous extractsLeaves ofTephrosia villosa (L.) Pers.West AfricaIn vitro EHIA and larval development assays againstH. contortus93.2 ± 0.9% inhibition of egg hatch and 81.8 ± 2.99% inhibition of larval development at 500 mg/ml [94](75)Aqueous extractsLeaves ofTephrosia vogelii Hook.f.Tropical AfricaIn vitro EHIA and larval development assays againstH. contortusSignificant inhibition against of egg hatch (95.8 ± 1.71%) and larval development (99.0 ± 1.41%) at 500 mg/ml [94]Lamiaceae(76)Aqueous and ethanolic extractFlowers and roots ofLeonotis ocymifolia (Burm.f.) IwarssonSouthern and East AfricaIn vitro ovicidal and larvicidal activity againstH. contortusAqueous extract had ED50 = 0.25μg/mL against egg hatch and 100% larval development inhibition at 50 mg/ml [158](77)Aqueous and ethanolic extractAerial parts ofLeucas martinicensis (Jacq) R.Br.Tropical AfricaIn vitro ovicidal and larvicidal activity againstH. contortusED50 = 0.09μg/mL of aqueous extract against egg hatch and inhibited larval development by 99.85% at 50 mg/ml [158](78)Hexane and ethanolic extractsFruits ofOcimum basilicum L.West Tropical AfricaIn vitro activity against the earthwormE. eugeniaeEthanolic extract was most active causing paralysis in 11.85 ± 0.71 min and death in 24.74 ±  0.42 min at 5 mg/ml. This was significantly active than mebendazole, the positive control [159](79)Acetone extractLeaves ofOcimum gratissimum Forssk.Tropical AfricaIn vitro activity against adultH. placeiConcentration-dependent inhibition of parasites with LC50 of 17.70 mg/ml [160](80)Essential oilsWhole plant ofOcimum sanctum L.Across AfricaIn vitro assay againstC. elegans (wild type) larvaeOil and eugenol (ED50 of 62.1μg/mL) showed activity against C. elegans larvae [108](81)Essential oilAerial parts ofThymus bovei Benth.North AfricaIn vitro wormicidal action on adultP. posthumaAt 10 mg/ml, paralysis and death time were 19.61 ± 0.88 and 47.32 ± 0.94 min, respectively [161](82)Aqueous and methanolic extractsStem barks ofVitex doniana SweetTropical AfricaIn vitro assay against egg hatching ofC. elegans strainsAt 2 mg/ml, both extracts had 83.8% and 92.3% ovicidal activity, respectively, against the ivermectin-resistant strain DA1316 [106](83)Saponin fractionAerial parts ofTeucrium stocksianum Boiss.Tropical East and North AfricaIn vitro assay onP. posthuma, tapeworms (R. spiralis), and adult roundworms (A. galli)At 40 mg/ml, the fraction was 1.89, 1.96 and 1.37 times active than albendazole against the three organisms, respectively [65]Meliaceae(84)Aqueous, methanolic extract and fractionSeeds ofAzadirachta indica A. Juss.Tropical AfricaIn vitro EHIA and larval survival assay againstH. contortusAll fractions exhibited dose-dependent effects. Ethyl acetate fraction had LC50 = 21.32μg/ml against egg hatching and 83% wormicidal effects at 50 mg/ml 1 h postexposure [162](85)Aqueous and methanolic extractsIn vivo inhibition of FEC and larval counts in sheep naturally infected withH. contortus and Trichostrongyus sppBoth extracts induced 29.3% and 40.2% reduction in EPG on day 15 posttreatment with 3 g/kg [163](86)Aqueous extractLeaves ofAzadirachta indica A. Juss.In vitro activity againstP. posthuma, tapeworms (Raillietina spiralis) and roundworms (Ascaridia galli)The extract significantly reduced paralysis (17 ± 0.32, 13 ± 0.85, 19 ± 0.50 min) and death time (30 ± 0.11, 38 ± 1.20, 40 ± 0.50 min), respectively, against all parasites [164](87)Crude feedIn vivo efficacy against bovine strongylosisInduced about 98% FECR on day 14 posttreatment [165](88)Diethyl etheric, chloroformic, ethanolic and methanolic extractsIn vitro activity against microfilariae ofSetaria cerviMethanolic and ethanolic extracts were the most active with 87% and 60% mortality at 45 min posttreatment with 200μg/ml [166](89)Traditional preparationsIn vivo activity (FEC and TWC) againstH. polygyrus in mice26% FECR and 15% TWCR at 7 days posttreatment [84](90)Ethanolic extractsIn vitro activity against GIN and in vivo FECR assay in goats100% mortality at 100 mg/ml with 81% reduction in EPG on day 9 posttreatment [126](91)Aqueous extractsLeaves, stem, and root barks ofAzadirachta indica A. Juss.In vitro EHIA and larval inhibition against strongylid nematodes of small ruminantsDose-dependent activity with over 90% inhibition of survival and about 50% inhibition of egg hatch at 100 mg/ml [167](92)Aqueous and ethanolic extractsStem barkKhaya senegalensis A. Juss.West, Central and East AfricaIn vitro activity against larvae of strongyles, and in vivo against mixed intestinal nematodes in sheepBoth extracts are active with no significant difference between them. Ethanolic extract had LC50 of 0.51  mg/ml and 88.82% FECR at 500  mg/kg, respectively [168].(93)Aqueous and ethanolic extractsLeaves and bark ofKhaya senegalensis A. Juss.In vitro activity againstC. elegans (wild type) larvaeEthanolic extract of the bark and leaves had LC50 of 470μg/ml and 1.0  mg/ml, respectively, against C. elegans [144].(94)1 : 1 DCM: methanolic extractWhole plant ofLansium domesticum CorrêaTropical East AfricaIn vitro activity against L3, L4 and adultC. elegans (wild type, Bristol N2)Extract significantly reduced survival of adult worms to 59% [107].Musaceae(95)Dry feedLeaves ofMusa sppTropical AfricaIn vivo assay againstH. contortus, and T. colubriformis in sheepSignificant inhibition of egg hatching inT. colubriformis (91% on day 15 posttreatment) [169](96)Aqueous extractsLeaves, pseudostems, and hearts ofMusa spp.Tropical AfricaIn vitro activity against larval development inH. contortusSignificant inhibition of larval development (>96.9%) recorded at 75 mg/ml [170](97)Aqueous extractsLeaves, pseudostems, and heart ofMusa spp. cv. Prata anãTropical AfricaIn vitro egg hatch, and larval development assays, and in vivo FEC reduction assay againstH. contortus in lambsThe leaf extract exhibited ovicidal (LC50 = 0.19 mg/ml) and larvicidal activities in vitro, and 33.0% FECR after 1 week of treatment with 303 mg/kg body weight [171](98)Dry feedLeaves ofMusa x paradisiaca L.Tropical AfricaIn vivo assay as feed for lambs experimentally infected withH. contortusSignificant FECR after 21 consecutive days of feeding with 7000 g/lamb/day [172](99)Hydromethanolic extractsIn vitro activity againstH. contortus eggs, adult motility assay in vivo effect on FEC and larval counts in sheep naturally infected with mixed species of nematodesExtract exhibited strong in vitro activity on egg hatching (LC50 = 2.13μg/mL) and caused 80.7% reduction in FEC in vivo at 8 g/kg body [173](100)Methanolic extractsRoots ofMusa spp. (M. paradisiaca, M. sapientum, and M. nana)Tropical AfricaIn vitro assay against sheep tapeworm (Moniezia benedeni), roundworm (Ascaris lumbricoides), and adult earthworm (Esenia fetida)All extracts showed significantly paralytic effects on the worms.M. paradisiaca was more active with 26.07 ± 1.7, 57.08 ± 1.32, and 80.04 ± 0.5 min paralysis time against the three worms, respectively [173]Phyllanthaceae(101)Methanolic and chloromethylenic extractsLeaves and bark ofBridelia ferruginea Benth.Tropical AfricaIn vitro activity againstRhabditis pseudoelongataThe dichloromethane extracts were more active than the methanolic extracts with EC50 of 2.5μg/ml and 5μg/ml, respectively [145](102)Hydroethanolic extractShoots ofPhyllanthus urinaria L.Tropical AfricaIn vitro action againstC. elegans larvaeExtract caused 10.8% inhibition of larvae (89.2% survival) at 1 mg/ml [149]Piperaceae(103)Aqueous extractSeeds ofPiper guineense Thonn.West, East, And Central AfricaIn vitro EHIA against mixed intestinal nematodes of goats90% inhibition of egg hatch at 100 mg/ml [87]((104)In vitro effects on adultL. terrestrisExtract induced 100% mortality of worms at 40 ± 0.68 min [138]((105)Ethanolic extractsSeeds ofPiper betle L.Tropical East AfricaIn vitro activity against GIN from goats70% mortality at 100 mg/ml [126]Poaceae(106)Acetone extractLeaves ofCymbopogon citratus Stapf.Tropical AfricaIn vitro activity against adultH. placeiExtract was active against the worm with LC50 of 56.04 mg/ml [160](107)Ethanolic extractCynodon dactylon (L.) Pers.Tropical East AfricaIn vitro activity against GIN from goatsExtract exhibited 50% mortality at 100 mg/ml [126]Primulaceae(108)Aqueous and ethanolic extractsSeeds ofEmbelia rowlandii GilgTropical West AfricaIn vitro ovicidal and larvicidal activities of extracts againstH. bakeriThe two extracts showed concentration-dependent ovicidal (82.5 and 46.9%), hatch inhibition (85.8 and 41.0%), andL1 larvicidal (86.0 and 61.2%) effects, respectively, at 5 mg/ml [174](109)Aqueous extractFruits and leaves ofMyrsine africana L.East and South AfricaIn vivo efficacy againstHaemonchus spp., Trichostrogylus spp., and Oesophagostomum spp. mixed infection in sheepExtract exhibited 77% efficacy against the parasites [157](110)Traditional preparationsSeeds ofMyrsine africana L.In vivo activity (FEC and TWC) againstH. polygyrus in mice16% FECR and 10% TWCR at 7 days posttreatment [84](111)Feed pasteFruits ofRapanea melanophloeos L.Tropical AfricaIn vivo activity againstH. polygyrus in miceModerate reduction in FEC and with no apparent effects on total worm counts [84]Rosaceae(112)Serial ether, chloroformic, methanolic, and chloromethylenic extractsStem bark ofHagenia abyssinica Bruce J.F. GmelEthiopia, Malawi, Tanzania, DRCIn vitro activity againstPanagrellus redivivus and C. elegansRelatively polar extracts possess anthelmintic activities against the test organisms. Methanolic extract at 20 mg/ml caused 67% mortality inC. elegans after 24 h [105](113)Methanolic extractFruits ofRubus fruticosus MarshallNorth AfricaIn vitro activity againstR. spiralis and A. galli89.83% and 84.2% parasiticidal activity at 40 mg/ml againstR. spiralis and A. galli, respectively [175]Rubiaceae(114)Ethanolic, aqueous extractsStem bark ofCanthium mannii Hiern.West AfricaIn vitro EHIA againstAncylostoma caninumEthanolic extract caused 90% egg hatch inhibition at 1 mg/ml after 48 h. The aqueous extracts had <50% eclodibility inhibition [96](115)Methanolic and chloromethylenic extractsLeaves and roots ofMorinda lucida A. GrayTropical AfricaIn vitro activity againstR. pseudoelongataBoth extracts were active with EC50 of 2.5μg/ml against the worms [145](116)Hydroethanolic extractStem bark ofZanthoxylum zanthoxyloides A. GrayIn vitro action againstP. posthumaExtract induced dose-dependent inhibition with paralysis and death time of 18.17 ± 0.03 and 24.34 ± 0.21 min, respectively, at 50 mg/ml [176](117)Ethanolic extractLeaves ofMorinda lucida A. GrayIn vitro effects on egg hatching, infective larvae, and adult worms ofT. colubriformisConcentration-dependent ovicidal effect, with 18% inhibition of motility at 48 h of 2.5 mg/ml treatment [177](118)Aqueous and ethanolic extractsLeaves ofNauclea latifolia Sm.West and Central AfricaIn vitro EHIA againstH. contortus, Trichostrongylus spp., Strongyloides spp., Trichuris ovis and Oesophagostomum spp. and in vivo in sheep naturally infected with ovine nematodesLC50 of 0.704 and 0.650 mg/ml for the aqueous and ethanolic extract in vitro, respectively, for mixed parasites. Both extracts caused reduction of FEC in vivo with improved haemoglobin and leukocytosis in worm-infested sheep [95](119)Aqueous extractStem bark ofNauclea latifolia Sm.In vivo efficacy study against strongyle ovine nematodesFEC was significantly reduced (93.8%) in infected animals treated with 1600 mg/kg body weight for 5 consecutive days [178]Rutaceae(120)Ethanolic extractRoots ofClausena anisate (Willd.) Hook. F.Tropical AfricaIn vitro LMIA againstAscaris suumExtracts were significantly active with EC50 of 74μg/mL [24](121)DCM -methanolic (1:1) extractRoot bark ofTeclea trichocarpa Engl.East AfricaIn vitro EHIA and larval development inStrongyloidesEffective against egg hatching (IC50 = 185.25μg/mL) and but not larval development at 1 mg/ml [93](122)Ethanolic extractRoot bark ofZanthoxylum zanthoxyloides (Lam.) Zepern. & TimlerWest AfricaIn vitro LMIA againstAscaris suumExtract inhibited larval migration with EC50 of 164μg/mL [24](123)Ethanolic extractLeaves of Zanthoxylum zanthoxyloides (Lam.) Zepern. & TimlerIn vitro effects on egg hatching, infective larvae, and adult worms ofTrichostrongylus colubriformisSignificant inhibition of adult worm motility (87% after 48 of 2.5 mg/ml treatment) [177]Zingiberaceae(124)Methanolic and chloromethylenic extractsLeaves and rhizomes ofAframomum sceptrum (Oliv. & D. Hanb.) K. Schum.West Tropical AfricaIn vitro activity againstRhabditis pseudoelongataBoth extract and alkaloid fraction were active with EC50 of 2.5μg/ml against the worms [145](125)Aqueous extractLeafy stems ofAframomum alboviolaceum (Ridl.) K. SchumTropical AfricaIn vitro effects on adultL. terrestrisExtract caused 100% mortality at 86 ± 3.21 min [138](126)Crude powderRhizomes ofZingiber officinale RoscoeTropical AfricaIn vivo FEC in pigs experimentally infected withS. ransomi, H. rubidus, T. axei and G. urosubulatusThe powder significantly reduced FEC (92.6% with 25 g/kg treatment againstS. ransomi) [179](127)Aqueous extract and powderIn vivo FEC assay against mixed nematode infection in sheepBoth powder and extract caused a dose-dependent reduction in FEC (25.6% and 66.6%, respectively) [180]Others(128)Hydromethanolic extractsWhole plant ofTrianthema portulacastrum L. (Aizoaceae)Tropical AfricaIn vitro EHIA, adult motility assay againstH. contortus. In vivo FEC assay in sheep naturally infected with mixed species of nematodesExtract strongly inhibited egg hatching (LC50 = 2.41μg/mL) and significantly reduced FEC (85.6% at 8.0 g/kg on day 15 posttreatment) [181](129)Aqueous and ethanolic extractsSeeds ofCoriandrum sativum L. (Apiaceae)Tropical East AfricaIn vitro EHIA and effects on adult worms, and in vivo FEC assay againstH. contortus in sheepBoth extracts were active against egg hatching (ED50 = 0.12 and 0.18 mg/ml resp.), and moderately reduced FEC (24.5% at 0.9 g/kg) [182](130)Ethanolic extractIn vitro and in vivo FEC assay againstHymenolepis nana in miceExtracts paralysed and killed the worms within 30 min and caused a 100% FECR at 500 mg/kg on day 15 posttreatment [114](131)Aqueous and hydroethanolic extractsRipe fruits ofHedera helix L. (Araliaceae)North and South AfricaIn vitro EHIA, faecal worm burden and adult worm mortality, and in vivo FEC assay againstH. contortus in sheepBoth extracts reduce faecal parasite count (44.2% at 2.25 g/kg) and produced ovicidal effects; ED50 = 0.12 and 0.17 mg/ml for aqueous and hydroalcoholic extracts, respectively [183](132)Ethyl acetate extractHusk of green fruits ofCocos nucifera L (Arecaceae)Lowland Tropical AfricaIn vitro egg hatching and larval development assays againstH. contortus. In vivo FEC assay in sheepExtract exhibited larvicidal (99.77% inhibition at 80 mg/ml) and ovicidal (100% inhibition at 5 mg/ml). No statistically significant activity was observed in vivo [184](133)Aqueous acetone extractsLeaves ofNewbouldia laevis (P. Beauv.) Seem. (Bignoniaceae)West AfricaIn vitro action against larval exsheathment inH. contortus and T. colubriformisConcentration-dependent inhibition ofH. contortus and T. colubriformis larval exsheathment (81.65% and 78.6%, respectively) at 600μg/ml [185](134)Ethanolic extractIn vitro effects on egg hatching, infective larvae, and adult worms ofTrichostrongylus colubriformis100% inhibition of adult worm motility after 48 of 2.5 mg/ml treatment [177](135)Ethanolic extractsLeaves ofAnanas comosus (L.) Merr. (Bromeliaceae)Tropical AfricaIn vitro activity against GIN and in vivo FECR assay in goats100% mortality at 100 mg/ml and 73% reduction in EPG on day 9 posttreatment [126](136)Aqueous extractsLeaves, stem, and root barks ofCanna bidentata Bertol. (Cannaceae)Tropical AfricaParalysis and death time in vitro assay against earthwormE. eugeniaeConcentration-dependent activity was observed. Root extract caused paralysis and death at 3 ± 0.00 and 5 ± 0.15 min, respectively [128](137)Hydroethanolic extractSeeds ofBuchholzia coriacea Engl. (Capparaceae)West and Central Africain vitro assay againstL3 larvae of Haemonchus contortus and Heligmosomoides polygyrusSignificant larvicidal activity causing 94% and 100% mortality against the two parasites at 100 mg/ml, respectively, and IC50 of 16.82 and 11.20 mg/ml, respectively [117]In vivo assay in chicken experimentally infected withAscardia galliExtract had no effect on worm load and FEC in the infected animals [117](138)LatexUnripped fruits ofCarica papaya L. (Caricaceae)Tropical AfricaIn vivo anthelmintic efficacy againstAscaridia galli and Cappilaria spp. in poultryLatex caused 77.7% reduction in FEC after 1 week of treatment [186](139)Aqueous extractsSeeds ofCarica papaya L. (Caricaceae)In vivo against GI nematodes in naturally infected goatsExtract exhibited significant reduction in FEC (100%) in 7 days after drenching with 100 mg/ml [187](140)In vivo assay against FEC ofH. contortus, Trichostrongylus spp, Strongyloides spp, and Ostertagia spp. in sheepExtracts showed 100% reduction in FEC in listed worms after 7 days treatment with 100 mg/ml [188].(141)In vivo against FEC in mixed infections in chicksImproved haematological indices and significantly (100%) reduced FEC in chicks after 2 weeks of treatment with 1 : 10 ml (w/v) extract [116](142)In vivo assay againstH. contortus, Oesophagostomum spp., Trichostrongylus spp., and Cooperia spp. in goatsImproved haematological indices and a significant (100%) FECR 2 weeks after drenching with 1 : 10 ml (w/v) extract) [111](143)Ethanolic extractIn vitro assay against egg hatch, larvae, and adult worms ofT. colibriformisSignificant inhibition of all stages of the worm with 90.5% immobilisation after 48 h treatment at 2.5 mg/ml [177](144)Ethanolic and chlorofomic extractsSeeds ofCarica papaya L. (Caricaceae)In vitro activity against adultP. posthumaEthanolic extract was the most active, inducing paralysis and death at 6.69 ± 0.68 and 19.75 ± 0.73 min, respectively, at 75 mg/ml [142](145)Ethanolic and hydroethanolic extractsLeaves, stem bark, and seeds ofCarica papaya L. (Caricaceae)Comparative in vitro anthelmintic effect of extracts against adultP. posthumaAll extracts induced paralysis and caused death of worms, Seeds were more active with 7.21 ± 0.01 and 9.15 ± 0.01 paralysis and death times, respectively, at 5 mg/ml [6](146)Aqueous extractsLeaves and seeds ofCarica papaya L. (Caricaceae)In vitro EHIA and larval development assays againstH. contortusSeeds extract was most active (LD50 of 49.94 mg/ml for egg hatch and 49.32 mg/ml against larval development) [94](147)Hydroethanolic extractSeeds ofGarcinia kola (Heckel) (Clusiaceae)West and South AfricaIn vitro EHIA, and larval mortality assay againstHeligmosomoides bakeri18.75% inhibition of the egg-hatch at 100 mg/ml and 76.52% irreversible paralysis of the larvae at 50 mg/ml [91](148)Aqueous extractIn vitro larvicidal effects against strongylid nematodes of goatsExtract exhibited larvicidal action with 53.3%, 66.6% and 73.3% mortality at 50, 100, and 150 mg/ml, respectively [189](149)Hydroethanolic extractStem bark ofGarcinia kola Heckel (Clusiaceae)In vitro action againstP. posthumaExtract induced dose-dependent paralysis and death of the adult worms at 39.29 ± 0.12 and 54.29 ± 0.01 min, respectively, for 50 mg/ml [176](150)Aqueous extractsSeeds and stem bark ofGarcinia kola Heckel (Clusiaceae)In vitro EHIA against strongylid nematodes of small ruminantsBoth extracts were ovicidal (98.9% and 100%, respectively) at 100 mg/ml [190](151)Aqueous extractRoot bark ofHildebrandtia sepalosa Rendle (Convolvulaceae)Tropical AfricaIn vivo efficacy againstHaemonchus spp., Trichostrogylus spp. and Oesophagostomum spp. mixed infection in sheepA 90% reduction in FEC was observed on day 12 posttreatment [157](152)Methanolic extractWhole plant ofCyperus difformis L. (Cyperaceae)AfricaIn vitro action againstP. posthumaThe extract showed a concentration-dependent paralysis (66.67 ± 1.8 min) and death (140.7 ± 2.3 min) at 20 mg/ml, respectively. It also improved the activity of albendazole, mebendazole and levamisole when 2 mg/ml of the extract was combined with these drugs [100](153)Ethanolic extractLeaves ofDiospyros mespiliformis Hochst. ex A. DC. (Ebenaceae)Tropical AfricaIn vivo assay against fecundity of adultH. contortus in sheepExtract induced about 55.08% reduction in FEC at 200 mg/kg dose [191](154)Ethanolic extractRoots ofAnthocleista djalonensis A. Chev. (Gentianaceae)West Tropical AfricaIn vitro againstL3 larvae of H. polygyrusConcentration-dependent lethal effects onL3 larvae with LC50 of 268.89 mg/ml [192](155)Hydromethanolic extractStem bark ofSacoglottis gabonensis (Baill.) Urb. (Humiriaceae)West Tropical AfricaIn vitro EHIA, and larval mortality assay againstHeligmosomoides bakeri100% larval paralysis at 15.63 mg/ml [91](156)1 : 1 DCM: methanolic extractWhole plant, and leaves ofPicria fel-terrae Lour. (Linderniaceae)North and East AfricaIn vitro effects on various stages ofH. contortusExtracts showed considerable activity against the parasitic larval stages ofH. contortus. It inhibited (94.1%) the development of L3 to L4 larvae 7 days posttreatment [193](157)In vitro activity againstL3, L4 and adult C. elegans (wild type, Bristol N2)Both extracts significantly affected all 3 stages ofC. elegans. It produced 50% defective egg laying phenotypes [107](158)Aqueous fraction of an ethanolic extractWhole plant ofSpigelia anthelmia L. (Loganiaceae)West AfricaIn vivo efficacy inNippostrongylus braziliensis infected ratsEfficacy of 74.35 ± 22.29% at 25 mg/kg body weight [194](159)Ethanolic extractFruit peels ofPunica granatum L. (Lythraceae)EthiopiaIn vitro LMIA againstAscaris suumExtracts active against larval migration with EC50 of 97μg/mL [24](160)Ethanolic extractLeaves ofCorchorus olitorius L. (Malvaceae)Tropical AfricaIn vitro activity against GIN from goatsExtract induced 60% mortality at 100 mg/ml [126](161)Chloroformic, pet. ether and ethanolic extractsLeaves ofMemecylon umbellatum Burm. (Melastomataceae)Tropical AfricaIn vitro activity against adultPheretima posthumaEthanolic extract was most potent with paralysis and death time of 29.66 ± 0.66 and 42.33 ± 1.45 min, respectively [195](162)Ethanolic extractFruits and seeds ofSphenocentrum jollyanum Pierre (Menispermaceae)Tropical AfricaIn vitro activity against adult earthwormsEudrilus eugeniae, H. placei, and T. saginataSeed extract caused paralysis and death at 18 ± 0.35 and 133 ± 3.75 min, respectively, againstE. Eugeniae [196](163)Feed for snailsLeaves ofMoringa oleifera Lam. (Moringaceae)West AfricaIn vivo against roundworms in snails (Achatina achatina)Significant prevention of parasitisation (c2 (1) = 14.97; p=0.0001) was observed in the treated snails [197](164)Methanolic extractStem bark ofPycnanthus angolensis (Welw.) Warb. (Myristicaceae)Tropical AfricaIn vitro activity against adult earthwormsEudrilus eugeniae, H. placei, and T. saginataExtract showed potent activity against all worms studied. At 80 mg/ml, paralysis occurred in the earthworm at 41 ± 1.81 min and death at 67 ± 2.60 min [196](165)Ethanolic extractsFlower buds ofSyzygium aromaticum (L.) Merr. & L. M. Perry (Myrtaceae)Tropical AfricaIn vitro activity against GIN and in vivo FECR assay in goats100% mortality at 100 mg/ml and 85% FECR on day 9 posttreatment [126](166)Hydroethanolic and 1:1 DCM: methanolic extractsLeaves, trunk bark and root bark ofLophira lanceolata Tiegh. ex Keay (Ochnaceae)Tropical AfricaIn vitro activity against adultO. ochengi and L4 larvae of various strains of C. elegansAll extracts exhibited 100% inhibition ofO. ochengi at 20μg/mL after 72 h. Ethanolic extract of the leaves was the most active against the drug-resistant strains [68](167)Methanolic and chloromethylenic extractsLeaves ofAdenia lobata Engl. (Passifloraceae)Central AfricaIn vitro activity againstRhabditis pseudoelongataBoth extracts were active with EC50 of 5μg/ml each against the worms [145](168)Ethyl acetate and methanloic extractsLeaves ofPlumbago zeylanica L. (Plumbaginaceae)Tropical AfricaIn vitro effects on paralysis and mortality ofP. posthumaEthyl acetate extract was the most active of the two causing paralysis and death at 59.85 ± 3.35 and 80.55 ± 2.66 min, respectively [198](169)Aqueous and ethanolic extractLeaves and roots ofRumex abyssinicus Jacq. (Polygonaceae)East AfricaIn vitro ovicidal and larvicidal activity againstH. contortusED50 = 0.11μg/mL of aqueous extract against egg hatch [158](170)Methanolic extractBark ofZiziphus nummularia (Burm.f.) Wight & Arn. (Rhamnaceae)North AfricaIn vitro EHIA, adult motility, and larval development assay againstH. contortus and in vivo against H. contortus, T. circumcincta, and T. ovis in sheep.LC50 = 676.08 and 398.11μg/ml against egg hatch and larval development, respectively. FECR (84.7%) was recorded on day 13 post 3.0 g/kg treatment [97](171)Hydroethanolic extractRoot bark ofPaullinia pinnata L. (Sapindaceae)Tropical AfricaIn vitro action againstC. elegans larvaeExtract caused 14.8% inhibition of larvae (85.2% survival) [149](172)Hydroethanolic extractIn vitro mortality assay against larvae ofC. elegans, Toxocara cati, Ancylostooma caninum, and Trichuris vulpis. EHIA and LMIA against H. contortusExtract was active against some of the test organisms.C. elegans (LC50 of 2.5  mg/ml), T. cati (LC50 of 112μg/mL), and T. vulpis (LC50 = 17μg/mL) [199].(173)Aqueous-acetone extract, ethyl acetate, and water partitionsIn vitro action againstC. elegans larvaeEthyl acetate partition was more effective (LC50 = 1.1 mg/ml) than the crude extract (LC50 = 1.9 mg/ml) and water fraction (LC50 = 2.9 mg/ml) [200](174)PAC fractionsIn vitro action againstC. elegans larvaeAll PAC fractions exhibited a minimum of 70% inhibition against the larvae [200](175)Methanolic and chloromethylenic extractsLeaves and roots ofPaullinia pinnata L. (Sapindaceae)In vitro activity againstRhabditis pseudoelongataExtracts of both parts were active against the worm with EC50 of 2.5μg/ml [145](176)Aqueous methanolic extractAerial parts ofVerbascum thapsus L. (Scrophulariaceae)North AfricaIn vitro activity againstR. spiralis and A. galliExtract produced relative paralysis index of 2.08 at 40 mg/ml againstA. galli [201](177)Methanolic extractDried fruits ofBrucea javanica (L.) Merr. (Simaroubaceae)Tropical East AfricaIn vivo activity againstDactylogyrus intermedius in goldfishExtract showed profound activity against the parasites (EC50 = 49.96 mg/L) [113](178)Aqueous and alcoholic extractsLeaves ofNicotiana tabacum L. (Solanaceae)Tropical AfricaIn vitro assay against motility ofMarshallagia marshalliExtracts significantly inhibited the motility of the worms, causing 0.44 death rate at 75 mg/ml [77](179)Aqueous and methanolic extractsIn vitro inhibition of motility againstH. contortus and in vivo FEC assay against H. contortus, T. axei, T. colubriformis, O. columbianum, S. Papillosus and T. ovis in sheepExtracts significantly inhibited worm motility at 6 h postexposure and caused a reduction in FEC (73.6% on day 5 posttreatment with methanolic extract at 3.0 g/kg) [202](180)Ethanolic extractsIn vitro activity against GIN from goats80% mortality at 100 mg/ml [126]The pharmacological potential of medicinal plants is attributed to their specific natural product composition, which can be influenced by various factors, including changes in environmental conditions [203]. To assess the pharmacological activities of individual constituents, they must first be isolated and characterized. The elucidated chemical structures provide grounds for quality control, structural modification, syntheses, elucidation of biosynthesis pathways, and quantitative structure-activity relations (QSAR) studies [7]. In this review, several bioactive anthelmintic compounds belonging to different biosynthetical classes have been isolated from medicinal plants native to Africa. Though there have been efforts to gather these antiparasitic phytochemical libraries [7, 23, 33], there exists no such profile for African medicinal plants. The majority of the studies reporting anthelmintic activities of medicinal plants focused on extracts or fractions with limited bioactive constituents [8]. Like the extracts, most of their activities have only been evaluated at the in vitro stage, with not much clinical reporting in animals or humans.Some specific compounds isolated from plants have been reported to exhibit anthelminthic activity (Table2 and Figure 1). Phenolic compounds such as tannins and flavonoids constitute a large class of natural molecules with potential anthelmintic or antiparasitic activities [74, 79, 244]. Because of their bulky structure and ability to bind several macromolecules, phenolic compounds have been reported to possess a broad range of biological activities. Oligomeric and polymeric proanthocyanidins, hydrolysable tannins, and flavonoids, for example, have been more intensively studied than any other class of natural anthelmintic compounds [79, 245]. A study conducted by Engström et al. [244] isolated and studied the in vitro activity of 33 hydrolysable tannins and gallic acid against egg hatching and larval motility of H. contortus. These compounds, isolated from various plants in Finland, showed varying anthelmintic activities [244]. Other studies isolated different types of proanthocyanidins from P. pinnata root bark and C. mucronatum leaves and reported varied activities against C. elegans and some animal intestinal parasites [150, 200]. Recent reviews on polyphenolics with anthelmintic potential have been published by Spiegler et al. [79] and Mukherjee et al. [246]. Alkaloids, coumarins, triterpenes, terpenoids, lignoids, prenylated derivatives, isothiocyanates formed after fermentation from glucosinolates, and saponins have also been widely isolated and studied [74]. Several fatty acids and aromatic compounds have also been reported to possess anthelmintic activities [247, 248]. Pineda-Alegría et al. [249] recently reported that long-chain fatty acids, including β-sitosterol, palmitic, pentadecanoic, stearic, and linoleic acids have nematocidal activity.Table 2
Anthelmintic compounds isolated from African medicinal plants.
No.CompoundChemical nature/groupPlant sourceReference(s)Habitats of plant in Africa(1)β-AsaronePhenylpropanoidRhizomes ofAcorus calamus L. and A. gramineus Aiton (Acoraceae)[204]Southern Africa(2)AspidinolPhloroglucinol derivativeLeaves ofLeucosidea sericea Eckl. & Zeyh. (Rosaceae)[205]Southern Africa(3)3-Geranyl-1-(2'-methylbutanoyl)-phloroglucinolPhloroglucinol derivativeLeaves ofHypericum roeperianum Schimp. ex.A.Rich. (Hypericaceae)[206]West Tropical Africa(4)α-BisabololSesquiterpeneLeaves ofSiparuna guianensis Aubl. (Siparunaceae)[207]West Africa(5)Betulinic acidTerpenoidStem bark ofBerlinia grandiflora (Vahl) Hutch. & Dalziel (Leguminosae)[208]West Africa(6)Ursolic acidTerpenoidsLeaves ofCurtisia dentata (Burm.f.) C.A.Sm (Cornaceae)[209]Southern Africa(7)Lupeol(8)Dichapetalin ATerpenoidsRoots ofDichapetalum filicaule Breteler (Dichapetalaceae)[210]West Africa(9)Dichapetalin X(10)Glycerol monostearate(11)ThymolMonoterpenoidEssential oils ofThymus vulgaris L. (Lamiaceae)[211]West Tropical Africa(12)AndrographolideTerpenoidLeaves ofAndrographis paniculata (Burm.f.) Nees (Acanthaceae)[212]East and South Africa(13)TotarolTerpenoidBerries ofJuniperus procera Hochst. Endl. (Cupressaceae)[213]East Africa(14)(3R, 6R)-Linalool oxide acetateMonoterpenoid(15)BorneolMonoterpenoidAerial parts ofZanthoxylum simulans Hance (Rutaceae)[214]West, Central and East Africa(16)β-Elemene(17)8(14),15-Sandaracopimaradiene-7α,18-diolDiterpeneLeaves ofTetradenia riparia (Hochst.) Codd (Lamiaceae)[215]East and South Africa(18)Terpinen-4-ol (4-carvomenthenol)MonoterpenoidEssential oilsof Melaleuca alternifolia (Maiden & Betche) Cheel (Myrtaceae)[216]South Africa(19)WarburganalSesquiterpeneLeaves ofWarburgia ugandensis Sprague (Canellaceae)[217]East and South Africa(20)Polygodial(21)2-Decanonet is ok mistake from meEssential oils from the aerial parts ofRuta chalepensis L. (Meliaceae)[218]North Africa(22)2-Nonanone(23)2-Undecanone(24)(E,E)-2-4-Decadienal(25)Furfural(26)Salicylaldehyde(27)EryngialCarbonalWhole herb ofEryngium foetidum Walter (Apiaceae)[219]Africa(28)tr-CinnamaldehydeCarbonalBark ofCinnamomum verum J. Presl. (Lauraceae)[220]Tropical Africa(29)AcetogeninPolyketideSeeds ofAnnona squamosa Delile (Annonaceae)[221]West Tropical Africa(30)(+)-Epicatechin-3-O-gallateProanthocyanidinsFruits ofAcacia nilotica (L.) Delile (Fabaceae)[110]Tropical Africa(31)(+)-Catechin-3-O-gallate(32)(+)-Gallocatechin(33)(−)-Epigallocatechin(34)(−)-Epigallocatechin-3-O-gallate(35)ProdelphinidinsProanthocyanidinsFlowers ofTrifolium repens L. (Papilionaceae)[203]South Africa(36)Ellagic acidSimple phenolicsLeaves and stem bark ofAnogeissus leiocarpus (DC.) Guill. & Perr. (Combretaceae)[15]Tropical, Central and East Africa(37)Gentisic acid(38)Gallic acidSimple phenolicFruits ofCaesalpinia coriaria (Jacq.) Willd. (Fabaceae)[222]West Africa(39)Caffeic acidCinnamic acid-like derivatives (phenolics)Leaves ofAcacia cochliacantha Willd. (Fabaceae)[223]Africa(40)Ferulic acid(41)p-Coumaric acidLeaves ofSenegalia gaumeri (S.F. Blake) Britton & Rose. (Fabaceae)[224]North-West Africa(42)6-GingerolPhenolicsRhizomes ofZingiber officinale Roscoe (Zingiberaceae)[225]Tropical Africa(43)6-Shogaol(44)10-Gingerol(45)10-Shogaol(46)Hexahydrocurcumin(47)Chlorogenic acidPhenolicAerial parts ofTagetes filifolia Lag. (Compositae)[226]Southern Africa(48)Joazeiroside BSaponinsStem bark ofZiziphus joazeiro Mart. (Rhamnaceae)[210]North Africa(49)Lotoside A(50)Urs-19(29)- en-3-yl acetateSaponinsLatex from the stem and leaves ofCalotropis procera (Aiton) Dryand. (Apocynaceae)[227]North and Tropical Africa(51)(3β)-Urs-19(29)-en-3-ol(52)1-(2′,5′-dimethoxyphenyl)-glycerol(53)TribulosinSpirostanol saponinsWhole plants ofTribulus terrestris L. (Zygophyllaceae)[228]Tropical Africa(54)β-Sitosterol-D-glucoside(55)DioscinSteroidal saponinsRhizomes ofParis polyphylla Sm. (Melanthiaceae)[229]South Africa(56)Polyphyllin D(57)AvenacosideSteroidal saponinSeeds ofAvena sativa L. (Poaceae)[230]Tropical Africa(58)UzarigeninCardenolidesBranches ofNerium indicum Mill. (Apocynaceae)[231]North Africa(59)Cardenolide N-1(60)3β-O-(β-D-Diginosyl)-14,15α-dihydroxy-5α-card-20(22)-enolide(61)ChelerythrineAlkaloidAerial parts ofChelidonium majus L. (Papaveraceae)[232]Northern Africa(62)PiperineAlkaloidStems ofPiper sylvaticum Roxb. (Piperaceae)[233]West Africa(63)6-Methoxydihydro-sanguinarineAlkaloidsAerial parts ofMacleaya macrocarpa (x kewensis) Turill (Papaveraceae)[234]North and South Africa(64)Sanguinarine(65)(S)-DicentrineAporphine alkaloidsAerial parts ofCissampelos capensis L. f. (Menispermaceae)[235]Southern Africa(66)(S)-Neolitsine(67)MelicopicineAcridine alkaloidsRoot bark ofTeclea trichocarpa Engl. (Rutaceae)[93]East Africa(68)6-Methoxytecleanthine(69)DeguelinIsoflavonoidsStem bark ofMundulea sericea (Wild.) A. Chev. (Leguminosae)[216]Southern Africa(70)RutinFlavonoidsAerial hay ofOnobrychis viciifolia Scop. (Fabaceae)[236]Tropical Africa(71)Nicotiflorin(72)Narcissin(73)LuteolinFlavonoidAerial parts ofAjania nubigena (Wall.) C. Shih (Compositae)[237]Africa(74)Galangal acetateFlavonoidSeeds ofTorreya grandis (Semen torreyae) Fortune ex Lindl. (Taxaceae)[33]Tropical West Africa(75)Miogadial(76)EpicatechinFlavan-3-olSeeds ofPersea americana Mill. (Lauraceae)[238]West Africa(77)(−)-Epigallocatechin-(2β⟶O⟶7′,4β⟶8′)-epicatechin-3′-O-gallateDimeric flavan-3-olLeaves ofCamellia sinensis (L.) Kuntze (Theaceae)[239]East Africa(78)Benzyl isothiocyanateIsothiocynatesSeeds ofCarica papaya L. (Caricaceae)[240]West, Central and East Africa(79)Bruceine AQuassinoidDried fruits ofBrucea javanica (L.) Merr. (Simaroubaceae)[113]East Africa(80)Bruceine D(81)FarnesolPrenyl alcoholsAerial parts ofMatricaria chamomilla Blanco (Compositae)[241]Northern and Southern Africa(82)Nerolidol(83)2H-Chromen-2-oneCoumarinLeaves ofGliricidia sepium (Jacq.) Walp. (Fabaceae)[242]West Tropical Africa(84)MimosineAmino acidLeaves ofLeucaena leucocephala (Lam.) de Wit. (Fabaceae)[243]Southern Africa(85)α-Linolenic acidFatty acidLeaves ofWarburgia ugandensis Sprague (Canellaceae)[217]East and South AfricaFigure 1
Chemical structures of compounds listed in Table2 against helminthiases.
(a)(b)(c)(d)(e)With the ever-increasing emergence of drug-resistant parasites and polyparasitism in animal and human helminthiases, there is a great need to explore the potential of developing some of the studied plants and their compounds into commercial drug products. The African herbal drug market should, therefore, explore the possibility of developing polyherbal formulations especially for use in livestock and companion animals, and as chemopreventive food supplements for humans.


## 6. Anthelmintic Activities of African Medicinal Plants

Medicinal plants belonging to different genera and families have been reported to have anthelmintic activities. However, some families have been frequently reported than others.


### 6.1. Fabaceae

This is the plant family with the highest reported number of plants with anthelmintic activities.Acacia nilotica (L.) Del. (Fabaceae), for instance, is a popular remedy for helminthiasis in Kenya [250]. Bachaya et al. [97] reported significant in vitro and in vivo activity of methanolic extracts of its fruits against the eggs (LC50 = 512.86 μg/mL) and larvae (LC50 = 194.98 μg/mL) of H. contortus and related ovine gastrointestinal nematodes. It also induced 78.5% reduction in FEC on day 13 post 3.0 g/kg treatment in sheep [97]. Similar effects were reported of its hydroalcoholic extracts against the larvae of C. elegans (wild type strain) and Onchocerca ochengi microfilariae with LC50 of 350 ± 1.1 μg/mL and 10.8 ± 0.3 μg/mL, respectively [110].The aqueous extract of the root bark ofAlbizia anthelmintica Brongn, a plant traditionally used as an anthelmintic [251, 252], revealed potent in vitro ovicidal (ED50 of 144.2 μg/mL) and larvicidal (ED50 of 65.2 μg/mL) activities against strongyle nematodes of sheep [86]. Gathuma et al. [157] also reported 89.8% in vivo efficacy of similar extracts of the plant in FECR assays against mixed GIN infections in sheep.OtherAcacia spp. have been reported to possess promissory anthelmintic activities against various test models. This included the leaves of A. polyacantha Wild [112], A. senegal, A. seyal, and A. tortilis [141]. Extracts of other fabaceous plants, such as leaves of Afrormosia laxiflora, Butea monosperma, Millettia ferruginea, Mimosa pudica, Senna occidentalis, Tephrosia spinosa, Tephrosia vogelii, and Tephrosia villosa, stem barks of Afzelia africana, Albizia schimperiana, Daniellia oliveri, and the seed kernel of Caesalpinia crista, have all been reported to exhibit a varying spectrum of anthelmintic activities [88, 89, 94, 98, 109, 118, 127, 141, 145, 158].


### 6.2. Combretaceae

One important species in the familyCombretaceae is Anogeissus leiocarpus (DC.) Guill. and Perr. (common name: Axlewood tree). It is widely used in African traditional practices and by livestock farmers for managing various parasitic disease conditions [89, 143, 145, 178]. Aqueous extracts of A. leiocarpus leaves caused 39.5% reduction in faecal egg count and 33% reduction in faecal worm burden in sheep treated with 400 mg/kg extract [143]. It also exhibited in vitro ovicidal (ED50 = 409.5 μg/mL) and larvicidal (100% excludability inhibition at 1.2 mg/mL) actions against H. contortus [89], whereas its acetone extract inhibited egg hatch (LC50 = 360 μg/ml) and larval development (LC50 = 509 μg/ml) [92]. Ndjonka et al. [144] reported that an ethanolic extract of A. leiocarpus bark was more active than an aqueous extract with LC50 of 380 μg/ml, significantly retarding the development of larvae into adult worms [144]. Another study reported significant in vitro activity of methanol and DCM extracts of leaves, roots, and bark against larvae of Rhabditis pseudoelongata with EC50 between 2.5 and 10 μg/ml [145].Combretum mucronatum Schumach and Thonn, traditionally used for various ailments including helminthiases in Africa [149, 253], has also been reported to exhibit anthelmintic activities against various test models. Ethanolic extract of C. mucronatum leaves exhibited in vitro nematocidal effects with 10 μg/mL minimum lethal concentration against T. muris and induced 85.3% reduction of worm burden in mice [148]. Hydroalcoholic extracts also inhibited C. elegans larvae with LC50 of 1.67 mg/mL. A partition of this extract revealed that the ethyl acetate portion possessed stronger anthelmintic activity than the remaining aqueous fraction. The respective activity can be related to the presence of oligomeric proanthocyanidins with different structures [150]. Subsequent ultrastructural studies showed that the tannin-rich extract caused visible effects on the cuticle without overt effects on the intestines/gut of the worms [151].Other plants from this family with reported potential anthelmintic activities includeAnogeissus schimperi, Combretum mole, Guiera senegalensis, Terminalia catappa, and Terminalia glaucescens [106, 145–147, 153].


### 6.3. Cucurbitaceae

Some plants belonging to this taxonomic family have also been investigated for anthelmintic effects. Ethanolic extracts ofMomordica charantia leaves collected from different ecological zones in Togo exhibited varying degrees of inhibition against C. elegans larvae with LC50 values between 473 and 997 μg/ml [155]. Similar extracts of its fruits also caused 100% mortality of GIN larvae at 100 mg/mL in vitro and 78% FECR on day 9 posttreatment of goats with 100 mg/kg [126]. Aqueous and ethanolic extracts of seeds of Citrullus lanatus, Cucurbita pepo, and Telfairia occidentalis all exhibited significant mortality and paralysis in vitro against the earthworm Lumbricus terrestris at 50 mg/mL [154].


### 6.4. Lamiaceae

Some plants belonging to theLamiaceae have been reported to possess anthelmintic properties. These include Ocimum sanctum L., whose essential oils and eugenol inhibited C. elegans larvae with ED50 of 62.1 μg/mL [108]. The aqueous extracts of roots of Leonotis ocymifolia (Burm.f.) Iwarsson and aerial parts of Leucas martinicensis (Jacq) R.Br. showed ovicidal (ED50 = 0.25 μg/mL and ED50 = 0.09 μg/mL, respectively), and larvicidal (100% and 99.85% inhibition, respectively, at 50 mg/mL) effects against H. contortus [158]. Whereas the fruits of O. basilicum L. were active against the earthworm E. eugeniae [159], the leaves of O. gratissimum and essential oils of Thymus bovei Benth., respectively, inhibited H. placei (LC50 of 17.70 mg/mL) [160] and P. posthuma (μg/mL) [161].


### 6.5. Meliaceae

Azadirachta indica A. Juss. (neem) is a widely known plant in African traditional medicine and contributes immensely to the management of livestock diseases and pests [254–256]. Almost every part of this plant has been reported to have anthelmintic activity. Polar extracts of neem seeds exhibited significant ovicidal and larvicidal action in vitro against H. contortus, with the ethyl acetate fraction causing 83% wormicidal effects at 50 mg/ml 1 h postexposure [162]. Aqueous and methanolic extracts of the seeds induced 29.3% and 40.2% reduction in EPG in sheep naturally infected with H. contortus and Trichostrongyus spp. on day 15 posttreatment with 3 g/kg [163]. Neem leaves also exhibited in vitro anthelmintic effects against the earthworm Pheretima posthuma, the tapeworm Raillietina spiralis, and the roundworm Ascaridia galli [164]. In vivo studies of feed in sheep reported significant inhibition of bovine nematodes, causing 98% reduction in FEC on day 14 posttreatment [165]. The leaf extracts also inhibited microfilariae of Setaria cervi in vitro [166] and caused a significant reduction in FEC and TWC against H. polygyrus in mice [84]. Sujon et al. [126] reported a 100% in vitro mortality at 100 mg/mL against GIN with 81% reduction in EPG on day 9 posttreatment of goats [126]. Leaves, stems, and root barks extracts inhibit strongyle nematodes, causing over 90% mortality of larvae at 100 mg/mL [167].Another medicinally relevant species from the family Meliaceae isKhaya senegalensis (Mahogany). Ethanolic extract of K. senegalensis bark induced in vitro LC50 of 0.51 mg/mL and 88.82% FECR at 500 mg/kg in sheep against strongyle nematodes [168]. Similar extracts of the bark and leaves had LC50 of 470 μg/mL and 1.0 mg/mL, respectively, against C. elegans larvae [144]. Methanol-dichloromethane extract of the whole plant of Lansium domesticum also inhibited adult C. elegans, significantly reducing their survival to 59% [107].


### 6.6. Musaceae

Musa spp. is the only genus in this family that has been reported to possess anthelmintic properties. Species such as M. x paradisiaca, M. sapientum, and M. nana inhibited the sheep tapeworm (Moniezia benedeni), roundworm (Ascaris lumbricoides), and adult earthworm (Esenia fetida), with M. x paradisiaca exhibiting the highest activity against the three worms [173]. M. x paradisiaca also caused significant FECR when fed to lambs infected with H. contortus [172] and in vitro ovicidal effects (LC50 = 2.13 μg/mL) against the same parasite [181]. Other preparations of various parts of Musa spp. demonstrated ovicidal activities against T. colubriformis in sheep [169], in vitro ovicidal and larvicidal effects against H. contortus, and reduction of FEC in sheep infected with H. contortus [170, 171].


### 6.7. Rubiaceae

Morinda lucida and Nauclea latifolia are two plants from this family for which anthelmintic potential has been widely reported. Methanol and DCM extracts of leaves and roots of M. lucida inhibited larvae of R. pseudoelongata with EC50 of 2.5 μg/mL [145], whereas hydroethanolic extracts of the stem bark induced dose-dependent paralysis (18.17 ± 0.03 min) and death (24.34 ± 0.21 min) at 50 mg/mL against P. posthuma [176]. Ethanolic extract of M. lucida leaves demonstrated concentration-dependent ovicidal action against T. colubriformis [177]. The aqueous and ethanolic extracts of N. latifolia leaves induced ovicidal activities (LC50 of 0.704 and 0.650 mg/ml, respectively) against ovine GIN and reduced faecal egg count when administered to naturally parasitised sheep [95]. Onyeyili et al. [178] reported significant reduction (93.8%) in FEC when sheep, infected with nematodes were treated with 1600 mg/kg body weight of aqueous extract of N. latifolia stem bark for 5 consecutive days [178]. Ethanolic extract of Canthium mannii stem bark induced 90% inhibition of egg hatching against Ancylostoma caninum at 1 mg/mL after 48 h incubation [96].


### 6.8. Other Plant Species with Anthelmintic Activities

#### 6.8.1.Carica papaya L. (Caricaceae)

Although the only plant in this family whose anthelmintic activities have been reported,Carica papaya (pawpaw) is one African medicinal plant whose anthelmintic potential has been widely investigated. Investigations on various extracts and parts of this plant have all reported some level of anthelmintic activity. Latex exudate from unripe fruits of C. papaya significantly reduced FEC (77.7%) of Ascaridia galli and Cappilaria spp. in poultry after one week of treatment [186]. After one week of posttreatment with 100 mg/mL, aqueous extracts of papaya seeds caused 100% reduction in FEC of GIN in goats [187] and sheep [188]. The seed extract also induced 100% reduction in FEC two weeks posttreatment in chicks [116] and goats [111]. In vitro studies reported that C. papaya seed extracts caused significant paralysis and death of adult P. posthuma [142] and inhibited egg hatch, larvae, and adult worms of T. colibriformis [177]. An in vitro comparative study of the leaves, stem bark, and seeds extracts of C. papaya reported that the seed extracts were the most active against adult P. posthuma [6]. Aqueous extract of papaya seeds was again reported to have more active LD50 of 49.94 and 49.32 mg/ml against H. contortus egg hatch and larval development, respectively [94]. The anthelmintic activity of pawpaw can be related to the isothiocyanates, which are formed from the genuine glucosinolates.


#### 6.8.2.Vernonia amygdalina Del. (Asteraceae)

Vernonia amygdalina (bitter leaf) is an important vegetable in West and Central African dishes [99] and widely used in the treatment of intestinal worms across Africa [253, 254]. Anthelmintic studies of aqueous and ethanolic extracts of its leaves revealed significant paralytic effects (59.94 ± 8.25 and 33.18 ± 12.41 min, respectively) against the adult earthworm L. terrestris [99]. Acetone extract of V. amygdalina leaves exhibited 42% ovicidal effect, 70% larval migration inhibition and 90% adulticidal effects at 300 μg/mL against H. contortus [141]. Alawa et al. [131] reported no significant ovicidal effects of V. amygdalina leaves extract at 11.2 mg/mL against H. contortus [131]. Another study revealed that the chloroformic extract of the stem bark was more active against P. posthuma, inducing paralysis (11.95 ± 0.28 min) and death (41.74 ± 2.21 min), than its ethanolic counterpart [142]. The anthelmintic activity might be related to the presence of sesquiterpene lactones.


#### 6.8.3.Garcinia kola Heckel (Clusiaceae)

Commonly referred to as “bitter kola,”Garcinia kola is used to treat gastrointestinal helminthiases [190] and has been shown to possess this activity in pharmacological screenings. Hydroethanolic extract of G. kola seeds induced 76.5% irreversible paralysis of H. bakeri larvae at 50 mg/mL [91] whilst its aqueous extract exhibited 53.3% larvicidal effects against strongylid nematodes of goats at same concentration [189]. At 50 mg/mL, the stem bark extract induced dose-dependent paralysis and death of the adult P. posthuma at 39.29 ± 0.12 and 54.29 ± 0.01 min, respectively, for 50 mg/mL [176]. Both the seed and stem bark extracts were ovicidal (98.9% and 100%, respectively) at 100 mg/mL against strongylid nematodes [190].


#### 6.8.4.Paullinia pinnata L. (Sapindaceae)

Paullinia pinnata is used in sub-Saharan Africa as an anthelmintic agent, especially for treating ancylostomiases [149, 258]. The anthelmintic properties of its root bark and leaves have been explored, revealing a huge potential as a source of nematocidal molecules, mainly oligomeric proanthocyanidins in the bark. Okpekon et al. [145] reported that extracts of both leaves and root bark of P. pinnata have in vitro inhibitory effects on R. pseudoelongata with EC50 of 2.5 μg/ml each [145]. The hydroethanolic extract of the root bark also reduced the survival of C. elegans larvae to 85.2% at 1 mg/mL [149]. Further in vitro investigations of this extract against some animal parasites and C. elegans revealed that the extract had significant activity against C. elegans (LC50 = 2.5 mg/mL), Toxocara cati (LC50 = 112 μg/mL) and Trichuris vulpis (LC50 = 17 μg/mL) [199]. Fractionation of water-acetone extracts leads to an ethyl acetate partition with better anthelmintic activity (LC50 = 1.1 mg/mL) than the water fraction (LC50 = 2.9 mg/mL) and the crude extract (LC50 = 1.9 mg/mL) [200]. Bioassay-guided studies led to the isolation of Cinnamtannin B1, a trimeric A-type procyanidin, which had significant inhibition of C. elegans (86.5% at 72 h incubation). The respective B-type trimer, procyanidin C1, isolated from C. mucronatum, was less active (47.3%), indicating a strong influence of the interflavan linkage and the different fine structures of the procyanidins [150, 200].


## 6.1. Fabaceae

This is the plant family with the highest reported number of plants with anthelmintic activities.Acacia nilotica (L.) Del. (Fabaceae), for instance, is a popular remedy for helminthiasis in Kenya [250]. Bachaya et al. [97] reported significant in vitro and in vivo activity of methanolic extracts of its fruits against the eggs (LC50 = 512.86 μg/mL) and larvae (LC50 = 194.98 μg/mL) of H. contortus and related ovine gastrointestinal nematodes. It also induced 78.5% reduction in FEC on day 13 post 3.0 g/kg treatment in sheep [97]. Similar effects were reported of its hydroalcoholic extracts against the larvae of C. elegans (wild type strain) and Onchocerca ochengi microfilariae with LC50 of 350 ± 1.1 μg/mL and 10.8 ± 0.3 μg/mL, respectively [110].The aqueous extract of the root bark ofAlbizia anthelmintica Brongn, a plant traditionally used as an anthelmintic [251, 252], revealed potent in vitro ovicidal (ED50 of 144.2 μg/mL) and larvicidal (ED50 of 65.2 μg/mL) activities against strongyle nematodes of sheep [86]. Gathuma et al. [157] also reported 89.8% in vivo efficacy of similar extracts of the plant in FECR assays against mixed GIN infections in sheep.OtherAcacia spp. have been reported to possess promissory anthelmintic activities against various test models. This included the leaves of A. polyacantha Wild [112], A. senegal, A. seyal, and A. tortilis [141]. Extracts of other fabaceous plants, such as leaves of Afrormosia laxiflora, Butea monosperma, Millettia ferruginea, Mimosa pudica, Senna occidentalis, Tephrosia spinosa, Tephrosia vogelii, and Tephrosia villosa, stem barks of Afzelia africana, Albizia schimperiana, Daniellia oliveri, and the seed kernel of Caesalpinia crista, have all been reported to exhibit a varying spectrum of anthelmintic activities [88, 89, 94, 98, 109, 118, 127, 141, 145, 158].


## 6.2. Combretaceae

One important species in the familyCombretaceae is Anogeissus leiocarpus (DC.) Guill. and Perr. (common name: Axlewood tree). It is widely used in African traditional practices and by livestock farmers for managing various parasitic disease conditions [89, 143, 145, 178]. Aqueous extracts of A. leiocarpus leaves caused 39.5% reduction in faecal egg count and 33% reduction in faecal worm burden in sheep treated with 400 mg/kg extract [143]. It also exhibited in vitro ovicidal (ED50 = 409.5 μg/mL) and larvicidal (100% excludability inhibition at 1.2 mg/mL) actions against H. contortus [89], whereas its acetone extract inhibited egg hatch (LC50 = 360 μg/ml) and larval development (LC50 = 509 μg/ml) [92]. Ndjonka et al. [144] reported that an ethanolic extract of A. leiocarpus bark was more active than an aqueous extract with LC50 of 380 μg/ml, significantly retarding the development of larvae into adult worms [144]. Another study reported significant in vitro activity of methanol and DCM extracts of leaves, roots, and bark against larvae of Rhabditis pseudoelongata with EC50 between 2.5 and 10 μg/ml [145].Combretum mucronatum Schumach and Thonn, traditionally used for various ailments including helminthiases in Africa [149, 253], has also been reported to exhibit anthelmintic activities against various test models. Ethanolic extract of C. mucronatum leaves exhibited in vitro nematocidal effects with 10 μg/mL minimum lethal concentration against T. muris and induced 85.3% reduction of worm burden in mice [148]. Hydroalcoholic extracts also inhibited C. elegans larvae with LC50 of 1.67 mg/mL. A partition of this extract revealed that the ethyl acetate portion possessed stronger anthelmintic activity than the remaining aqueous fraction. The respective activity can be related to the presence of oligomeric proanthocyanidins with different structures [150]. Subsequent ultrastructural studies showed that the tannin-rich extract caused visible effects on the cuticle without overt effects on the intestines/gut of the worms [151].Other plants from this family with reported potential anthelmintic activities includeAnogeissus schimperi, Combretum mole, Guiera senegalensis, Terminalia catappa, and Terminalia glaucescens [106, 145–147, 153].


## 6.3. Cucurbitaceae

Some plants belonging to this taxonomic family have also been investigated for anthelmintic effects. Ethanolic extracts ofMomordica charantia leaves collected from different ecological zones in Togo exhibited varying degrees of inhibition against C. elegans larvae with LC50 values between 473 and 997 μg/ml [155]. Similar extracts of its fruits also caused 100% mortality of GIN larvae at 100 mg/mL in vitro and 78% FECR on day 9 posttreatment of goats with 100 mg/kg [126]. Aqueous and ethanolic extracts of seeds of Citrullus lanatus, Cucurbita pepo, and Telfairia occidentalis all exhibited significant mortality and paralysis in vitro against the earthworm Lumbricus terrestris at 50 mg/mL [154].


## 6.4. Lamiaceae

Some plants belonging to theLamiaceae have been reported to possess anthelmintic properties. These include Ocimum sanctum L., whose essential oils and eugenol inhibited C. elegans larvae with ED50 of 62.1 μg/mL [108]. The aqueous extracts of roots of Leonotis ocymifolia (Burm.f.) Iwarsson and aerial parts of Leucas martinicensis (Jacq) R.Br. showed ovicidal (ED50 = 0.25 μg/mL and ED50 = 0.09 μg/mL, respectively), and larvicidal (100% and 99.85% inhibition, respectively, at 50 mg/mL) effects against H. contortus [158]. Whereas the fruits of O. basilicum L. were active against the earthworm E. eugeniae [159], the leaves of O. gratissimum and essential oils of Thymus bovei Benth., respectively, inhibited H. placei (LC50 of 17.70 mg/mL) [160] and P. posthuma (μg/mL) [161].


## 6.5. Meliaceae

Azadirachta indica A. Juss. (neem) is a widely known plant in African traditional medicine and contributes immensely to the management of livestock diseases and pests [254–256]. Almost every part of this plant has been reported to have anthelmintic activity. Polar extracts of neem seeds exhibited significant ovicidal and larvicidal action in vitro against H. contortus, with the ethyl acetate fraction causing 83% wormicidal effects at 50 mg/ml 1 h postexposure [162]. Aqueous and methanolic extracts of the seeds induced 29.3% and 40.2% reduction in EPG in sheep naturally infected with H. contortus and Trichostrongyus spp. on day 15 posttreatment with 3 g/kg [163]. Neem leaves also exhibited in vitro anthelmintic effects against the earthworm Pheretima posthuma, the tapeworm Raillietina spiralis, and the roundworm Ascaridia galli [164]. In vivo studies of feed in sheep reported significant inhibition of bovine nematodes, causing 98% reduction in FEC on day 14 posttreatment [165]. The leaf extracts also inhibited microfilariae of Setaria cervi in vitro [166] and caused a significant reduction in FEC and TWC against H. polygyrus in mice [84]. Sujon et al. [126] reported a 100% in vitro mortality at 100 mg/mL against GIN with 81% reduction in EPG on day 9 posttreatment of goats [126]. Leaves, stems, and root barks extracts inhibit strongyle nematodes, causing over 90% mortality of larvae at 100 mg/mL [167].Another medicinally relevant species from the family Meliaceae isKhaya senegalensis (Mahogany). Ethanolic extract of K. senegalensis bark induced in vitro LC50 of 0.51 mg/mL and 88.82% FECR at 500 mg/kg in sheep against strongyle nematodes [168]. Similar extracts of the bark and leaves had LC50 of 470 μg/mL and 1.0 mg/mL, respectively, against C. elegans larvae [144]. Methanol-dichloromethane extract of the whole plant of Lansium domesticum also inhibited adult C. elegans, significantly reducing their survival to 59% [107].


## 6.6. Musaceae

Musa spp. is the only genus in this family that has been reported to possess anthelmintic properties. Species such as M. x paradisiaca, M. sapientum, and M. nana inhibited the sheep tapeworm (Moniezia benedeni), roundworm (Ascaris lumbricoides), and adult earthworm (Esenia fetida), with M. x paradisiaca exhibiting the highest activity against the three worms [173]. M. x paradisiaca also caused significant FECR when fed to lambs infected with H. contortus [172] and in vitro ovicidal effects (LC50 = 2.13 μg/mL) against the same parasite [181]. Other preparations of various parts of Musa spp. demonstrated ovicidal activities against T. colubriformis in sheep [169], in vitro ovicidal and larvicidal effects against H. contortus, and reduction of FEC in sheep infected with H. contortus [170, 171].


## 6.7. Rubiaceae

Morinda lucida and Nauclea latifolia are two plants from this family for which anthelmintic potential has been widely reported. Methanol and DCM extracts of leaves and roots of M. lucida inhibited larvae of R. pseudoelongata with EC50 of 2.5 μg/mL [145], whereas hydroethanolic extracts of the stem bark induced dose-dependent paralysis (18.17 ± 0.03 min) and death (24.34 ± 0.21 min) at 50 mg/mL against P. posthuma [176]. Ethanolic extract of M. lucida leaves demonstrated concentration-dependent ovicidal action against T. colubriformis [177]. The aqueous and ethanolic extracts of N. latifolia leaves induced ovicidal activities (LC50 of 0.704 and 0.650 mg/ml, respectively) against ovine GIN and reduced faecal egg count when administered to naturally parasitised sheep [95]. Onyeyili et al. [178] reported significant reduction (93.8%) in FEC when sheep, infected with nematodes were treated with 1600 mg/kg body weight of aqueous extract of N. latifolia stem bark for 5 consecutive days [178]. Ethanolic extract of Canthium mannii stem bark induced 90% inhibition of egg hatching against Ancylostoma caninum at 1 mg/mL after 48 h incubation [96].


## 6.8. Other Plant Species with Anthelmintic Activities

### 6.8.1.Carica papaya L. (Caricaceae)

Although the only plant in this family whose anthelmintic activities have been reported,Carica papaya (pawpaw) is one African medicinal plant whose anthelmintic potential has been widely investigated. Investigations on various extracts and parts of this plant have all reported some level of anthelmintic activity. Latex exudate from unripe fruits of C. papaya significantly reduced FEC (77.7%) of Ascaridia galli and Cappilaria spp. in poultry after one week of treatment [186]. After one week of posttreatment with 100 mg/mL, aqueous extracts of papaya seeds caused 100% reduction in FEC of GIN in goats [187] and sheep [188]. The seed extract also induced 100% reduction in FEC two weeks posttreatment in chicks [116] and goats [111]. In vitro studies reported that C. papaya seed extracts caused significant paralysis and death of adult P. posthuma [142] and inhibited egg hatch, larvae, and adult worms of T. colibriformis [177]. An in vitro comparative study of the leaves, stem bark, and seeds extracts of C. papaya reported that the seed extracts were the most active against adult P. posthuma [6]. Aqueous extract of papaya seeds was again reported to have more active LD50 of 49.94 and 49.32 mg/ml against H. contortus egg hatch and larval development, respectively [94]. The anthelmintic activity of pawpaw can be related to the isothiocyanates, which are formed from the genuine glucosinolates.


### 6.8.2.Vernonia amygdalina Del. (Asteraceae)

Vernonia amygdalina (bitter leaf) is an important vegetable in West and Central African dishes [99] and widely used in the treatment of intestinal worms across Africa [253, 254]. Anthelmintic studies of aqueous and ethanolic extracts of its leaves revealed significant paralytic effects (59.94 ± 8.25 and 33.18 ± 12.41 min, respectively) against the adult earthworm L. terrestris [99]. Acetone extract of V. amygdalina leaves exhibited 42% ovicidal effect, 70% larval migration inhibition and 90% adulticidal effects at 300 μg/mL against H. contortus [141]. Alawa et al. [131] reported no significant ovicidal effects of V. amygdalina leaves extract at 11.2 mg/mL against H. contortus [131]. Another study revealed that the chloroformic extract of the stem bark was more active against P. posthuma, inducing paralysis (11.95 ± 0.28 min) and death (41.74 ± 2.21 min), than its ethanolic counterpart [142]. The anthelmintic activity might be related to the presence of sesquiterpene lactones.


### 6.8.3.Garcinia kola Heckel (Clusiaceae)

Commonly referred to as “bitter kola,”Garcinia kola is used to treat gastrointestinal helminthiases [190] and has been shown to possess this activity in pharmacological screenings. Hydroethanolic extract of G. kola seeds induced 76.5% irreversible paralysis of H. bakeri larvae at 50 mg/mL [91] whilst its aqueous extract exhibited 53.3% larvicidal effects against strongylid nematodes of goats at same concentration [189]. At 50 mg/mL, the stem bark extract induced dose-dependent paralysis and death of the adult P. posthuma at 39.29 ± 0.12 and 54.29 ± 0.01 min, respectively, for 50 mg/mL [176]. Both the seed and stem bark extracts were ovicidal (98.9% and 100%, respectively) at 100 mg/mL against strongylid nematodes [190].


### 6.8.4.Paullinia pinnata L. (Sapindaceae)

Paullinia pinnata is used in sub-Saharan Africa as an anthelmintic agent, especially for treating ancylostomiases [149, 258]. The anthelmintic properties of its root bark and leaves have been explored, revealing a huge potential as a source of nematocidal molecules, mainly oligomeric proanthocyanidins in the bark. Okpekon et al. [145] reported that extracts of both leaves and root bark of P. pinnata have in vitro inhibitory effects on R. pseudoelongata with EC50 of 2.5 μg/ml each [145]. The hydroethanolic extract of the root bark also reduced the survival of C. elegans larvae to 85.2% at 1 mg/mL [149]. Further in vitro investigations of this extract against some animal parasites and C. elegans revealed that the extract had significant activity against C. elegans (LC50 = 2.5 mg/mL), Toxocara cati (LC50 = 112 μg/mL) and Trichuris vulpis (LC50 = 17 μg/mL) [199]. Fractionation of water-acetone extracts leads to an ethyl acetate partition with better anthelmintic activity (LC50 = 1.1 mg/mL) than the water fraction (LC50 = 2.9 mg/mL) and the crude extract (LC50 = 1.9 mg/mL) [200]. Bioassay-guided studies led to the isolation of Cinnamtannin B1, a trimeric A-type procyanidin, which had significant inhibition of C. elegans (86.5% at 72 h incubation). The respective B-type trimer, procyanidin C1, isolated from C. mucronatum, was less active (47.3%), indicating a strong influence of the interflavan linkage and the different fine structures of the procyanidins [150, 200].


## 6.8.1.Carica papaya L. (Caricaceae)

Although the only plant in this family whose anthelmintic activities have been reported,Carica papaya (pawpaw) is one African medicinal plant whose anthelmintic potential has been widely investigated. Investigations on various extracts and parts of this plant have all reported some level of anthelmintic activity. Latex exudate from unripe fruits of C. papaya significantly reduced FEC (77.7%) of Ascaridia galli and Cappilaria spp. in poultry after one week of treatment [186]. After one week of posttreatment with 100 mg/mL, aqueous extracts of papaya seeds caused 100% reduction in FEC of GIN in goats [187] and sheep [188]. The seed extract also induced 100% reduction in FEC two weeks posttreatment in chicks [116] and goats [111]. In vitro studies reported that C. papaya seed extracts caused significant paralysis and death of adult P. posthuma [142] and inhibited egg hatch, larvae, and adult worms of T. colibriformis [177]. An in vitro comparative study of the leaves, stem bark, and seeds extracts of C. papaya reported that the seed extracts were the most active against adult P. posthuma [6]. Aqueous extract of papaya seeds was again reported to have more active LD50 of 49.94 and 49.32 mg/ml against H. contortus egg hatch and larval development, respectively [94]. The anthelmintic activity of pawpaw can be related to the isothiocyanates, which are formed from the genuine glucosinolates.


## 6.8.2.Vernonia amygdalina Del. (Asteraceae)

Vernonia amygdalina (bitter leaf) is an important vegetable in West and Central African dishes [99] and widely used in the treatment of intestinal worms across Africa [253, 254]. Anthelmintic studies of aqueous and ethanolic extracts of its leaves revealed significant paralytic effects (59.94 ± 8.25 and 33.18 ± 12.41 min, respectively) against the adult earthworm L. terrestris [99]. Acetone extract of V. amygdalina leaves exhibited 42% ovicidal effect, 70% larval migration inhibition and 90% adulticidal effects at 300 μg/mL against H. contortus [141]. Alawa et al. [131] reported no significant ovicidal effects of V. amygdalina leaves extract at 11.2 mg/mL against H. contortus [131]. Another study revealed that the chloroformic extract of the stem bark was more active against P. posthuma, inducing paralysis (11.95 ± 0.28 min) and death (41.74 ± 2.21 min), than its ethanolic counterpart [142]. The anthelmintic activity might be related to the presence of sesquiterpene lactones.


## 6.8.3.Garcinia kola Heckel (Clusiaceae)

Commonly referred to as “bitter kola,”Garcinia kola is used to treat gastrointestinal helminthiases [190] and has been shown to possess this activity in pharmacological screenings. Hydroethanolic extract of G. kola seeds induced 76.5% irreversible paralysis of H. bakeri larvae at 50 mg/mL [91] whilst its aqueous extract exhibited 53.3% larvicidal effects against strongylid nematodes of goats at same concentration [189]. At 50 mg/mL, the stem bark extract induced dose-dependent paralysis and death of the adult P. posthuma at 39.29 ± 0.12 and 54.29 ± 0.01 min, respectively, for 50 mg/mL [176]. Both the seed and stem bark extracts were ovicidal (98.9% and 100%, respectively) at 100 mg/mL against strongylid nematodes [190].


## 6.8.4.Paullinia pinnata L. (Sapindaceae)

Paullinia pinnata is used in sub-Saharan Africa as an anthelmintic agent, especially for treating ancylostomiases [149, 258]. The anthelmintic properties of its root bark and leaves have been explored, revealing a huge potential as a source of nematocidal molecules, mainly oligomeric proanthocyanidins in the bark. Okpekon et al. [145] reported that extracts of both leaves and root bark of P. pinnata have in vitro inhibitory effects on R. pseudoelongata with EC50 of 2.5 μg/ml each [145]. The hydroethanolic extract of the root bark also reduced the survival of C. elegans larvae to 85.2% at 1 mg/mL [149]. Further in vitro investigations of this extract against some animal parasites and C. elegans revealed that the extract had significant activity against C. elegans (LC50 = 2.5 mg/mL), Toxocara cati (LC50 = 112 μg/mL) and Trichuris vulpis (LC50 = 17 μg/mL) [199]. Fractionation of water-acetone extracts leads to an ethyl acetate partition with better anthelmintic activity (LC50 = 1.1 mg/mL) than the water fraction (LC50 = 2.9 mg/mL) and the crude extract (LC50 = 1.9 mg/mL) [200]. Bioassay-guided studies led to the isolation of Cinnamtannin B1, a trimeric A-type procyanidin, which had significant inhibition of C. elegans (86.5% at 72 h incubation). The respective B-type trimer, procyanidin C1, isolated from C. mucronatum, was less active (47.3%), indicating a strong influence of the interflavan linkage and the different fine structures of the procyanidins [150, 200].


## 7. Conclusion

The World Health Organization’s 2030 targets for STH can only be achieved with renewed investments in new and effective drugs. African medicinal plants will serve as a useful source of remedies for integrated parasite control, along with other measures such as education and the provision of sanitation facilities to at-risk populations.The foregoing data validate the claims that African medicinal plants have huge potential for the discovery and development of new, innovative, and alternative anthelmintic agents. The majority of reports and studies evaluated extracts of plants, with a few isolated compounds also characterized. Even though in vivo animal studies abound, 78% of the studies reported in vitro activities against parasitic nematodes. There are no reports available on clinical investigations of extracts or purified compounds in humans, nor have any commercial products been reported or evaluated for their effectiveness. Therefore, clinical evaluation of these plant products and mechanistic studies, especially on isolated compounds, will advance the goal of identifying and developing drug candidates from plant sources. [256].



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*Source: 8023866-2022-12-31.xml*