# Ethnopharmacological Uses, Phytochemistry, and Pharmacological Properties ofCroton macrostachyus Hochst. Ex Delile: A Comprehensive Review

Authors: Alfred Maroyi
Journal: Evidence-Based Complementary and Alternative Medicine
 (2017)

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## Abstract

Croton macrostachyus is widely used as herbal medicine by the indigenous people of tropical Africa. The potential ofC. macrostachyus as herbal medicine, the phytochemistry, and pharmacological properties of its parts used as herbal medicines are reviewed. The extensive literature survey revealed thatC. macrostachyus is traditionally used to treat or manage at least 81 human and animal diseases and ailments. The species is used as herbal medicine for diseases and ailments such as abdominal pains, cancer, gastrointestinal disorders, malaria, pneumonia, sexually transmitted infections, skin infections, typhoid, and wounds and as ethnoveterinary medicine. Multiple classes of phytochemicals such as alkaloids, amino acids, anthraquinones, carbohydrates, cardiac glycosides, coumarins, essential oil, fatty acids, flavonoids, phenolic compounds, phlobatannins, polyphenols, phytosteroides, saponins, sterols, tannins, terpenoids, unsaturated sterol, vitamin C, and withanoides have been isolated from the species. Pharmacological studies onC. macrostachyus indicate that it has a wide range of pharmacological activities such as anthelmintic, antibacterial, antimycobacterial, antidiarrhoeal, antifungal, anticonvulsant and sedative, antidiabetic, anti-inflammatory, antileishmanial, antioxidant, antiplasmodial, and larvicidal effects.Croton macrostachyus has potential as a possible source of a wide range of pharmaceutical products for the treatment of a wide range of both human and animal diseases and ailments.


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## Body

## 1. Introduction

Croton macrostachyus Hochst. ex Delile is a species of the genusCroton L., Euphorbiaceae family, commonly known as the spurge family.Croton macrostachyus is a medium sized, drought-deciduous pioneer tree which regenerates naturally in less productive sites including forest edges, mountain slopes, and waste grounds under a wide range of ecological conditions [1–3].Croton macrostachyus is regarded as a multipurpose tree by subsistence farmers in Ethiopia, Kenya, and Tanzania [3–6], as it is often grown and managed in home gardens for provision of several ecosystem goods and services. In Ethiopia, for example,C. macrostachyus is a major tree intercropped in agroecosystems in order to increase soil productivity in midaltitude and semiarid areas [7]. There is also tremendous interest in the medicinal uses and pharmacological properties ofC. macrostachyus throughout its distributional range in tropical Africa [8–11]. Research by these authors revealed thatC. macrostachyus is an important medicinal plant in tropical Africa with potential of providing important pharmaceutical products to be used by rural and urban communities who rely on herbal medicines for primary healthcare. Integration of traditional medicine and modern medicine has been recommended by the World Health Organization (WHO) since 1978 [12], mainly because traditional medicines are perceived to be more affordable, accessible, and acceptable to poor rural and urban communities and those living in marginalized areas [13]. Considering the documented ethnomedicinal uses ofC. macrostachyus in tropical Africa [8–11], certainly the species has potential in playing an important role in the primary healthcare of communities throughout its distributional range. It is therefore important to assess if there is correlation between the ethnomedicinal uses ofC. macrostachyus and the recent documented phytochemical and pharmacological properties of the species. Therefore, the present review collates the fragmented information on traditional uses, phytochemistry, pharmacology, and toxicology of the species. It is hoped that this information will highlight the importance ofC. macrostachyus as a potential source of a wide range of pharmaceutical products in tropical Africa and will provide a new direction for researchers in the future.


## 2. Methodology of the Review

Croton macrostachyus and other historical names and synonyms of the species were used as the keywords in searching the major databases including Web of Science, Scopus, Google Scholar, Science Direct, BioMed Central (BMC), PubMed, and Springerlink documenting traditional uses, medicinal uses, ethnobotany, ethnomedicinal uses, ethnopharmacology, pharmacology, phytochemistry, and therapeutic value of the species. Additional literature, including preelectronic literature such as dissertations, theses, and other grey materials were sourced from the University of Fort Hare library in South Africa.


## 3. Botanical Profile, Taxonomy, and Distribution ofCroton macrostachyus

The genus name “Croton” was derived from a Greek word “kroton,” a tick, referring to thick smooth seeds, a common feature of mostCroton species which belong to the Crotonoideae subfamily of the Euphorbiaceae family [14]. The specific name “macrostachyus” is a contraction of two words, the Greek word “macro” meaning large and “stachyus” relating to the spike, hence, a species characterized by large spikes [15]. Historical names or synonyms ofC. macrostachyus areC. acuminatus R. Br.,C. butaguensis De Wild.,C. guerzesiensis Beille ex A. Chev.,C. macrostachyus var.mollissimus Chiov.,Oxydectes macrostachya (Hochst. ex Delile) Kuntze, andRottlera schimperi Hochst. & Steud. (http://www.theplantlist.org/tpl1.1/record/kew-50457).Croton macrostachyus is commonly known as “broad-leaved croton” or “rush foil” in English, “bisana” in Amharic in Ethiopia, and “msinduzi” in Swahili in east Africa [11, 16–24].Croton macrostachyus is widely distributed in tropical Africa, from Guinea east to Ethiopia and Somalia, south to Angola, Mozambique, and Madagascar (Figure 1). The species has been reported to occur in Angola, Burundi, Cameroon, Central African Republic, Democratic Republic of Congo (DRC), Ethiopia, Ghana, Guinea, Ivory Coast, Kenya, Madagascar, Malawi, Mozambique, Nigeria, Rwanda, Somalia, South Sudan, Sudan, Tanzania, Uganda, and Zambia [3, 25]. According to Mairura [11],C. macrostachyus is common in secondary forests, especially on forest edges and along rivers or lakes, in moist or dry evergreen upland forest, woodland, wooded grassland, bushland, and along roadsides, often on soils of volcanic origin at altitude between 200 to 3400 m above sea level and mean annual rainfall between 150 mm and 1200 mm.Figure 1
Distribution ofCroton macrostachyus in tropical Africa.Croton macrostachyus is a monoecious or dioecious, deciduous, medium sized tree up to 30 m tall [2]. The bole is cylindrical up to 100 cm in diameter with grey to grey-brown bark, finely fissured, and cracked, inner bark pale brown to reddish brown with a peppery smell [1]. The leaves are alternate, simple, turning orange before falling with linear stipules, up to 15 mm long [1]. The petiole is up to 20 cm long with two stalked glands at top [2]. The leaf blade is ovate-elliptical to almost circular, up to 25 cm × 20 cm in size with a cordate base and acuminate apex acuminate with irregularly toothed margins, densely stellate hairy on both sides, and whitish green beneath [1]. The inflorescence is a slender, terminal raceme up to 35 cm long, either with only male or female flowers or male and female flowers variably mixed [2]. Male flower has a pedicel which is 3–10 mm long with campanulate calyx with ovate to triangular lobes, 2.5–3.5 mm long with densely white hairy margins [1]. The petals are oblong to oblanceolate, 3–4.5 mm long and have 15–17 free stamens [1]. The female flower has a pedicel which is 2–4 mm long, fleshy, calyx as in male flowers but lobes more triangular, persistent in fruit, petals linear, or absent up to 1.5 mm long [1]. The ovary is superior, rounded, densely stellate hairy with three styles, 3–6 mm long, twisted, and curved [2]. The fruit is a globular capsule, 8–12 mm in diameter with a centrally depressed apex, whitish to pale greyish brown in colour. The seeds are ellipsoid, 6–8 mm × 4–5.5 mm in size, flattened, and cream-coloured [1].


## 4. Traditional and Contemporary Uses ofCroton macrostachyus

The bark, fruits, leaves, roots, and seeds ofC. macrostachyus are reported to possess diverse medicinal properties and cure various human and animal diseases and ailments throughout the distributional range of the species (Table 1).Croton macrostachyus is used as herbal medicine for at least 61 and 20 human and animal diseases and ailments, respectively (Table 1). There is cross-cultural agreement among ethnomedicinal uses ofC. macrostachyus throughout its distributional range, and there is also a high degree of medicinal use consensus (recorded in at least two countries) for bleeding, blood clotting, cancer, constipation, diarrhoea, epilepsy, malaria, pneumonia, purgative, ringworm, skin diseases or infections, stomach ache, typhoid, worm expulsion, and wounds (see Table 1).Table 1
Ethnomedicinal uses ofCroton macrostachyus in tropical Africa.
Use
Plant parts used
Country practiced
References
Abdominal pain
Leaf juice or decoction taken orally
Ethiopia, Tanzania
[26, 27]
Abdominal pain
Bark decoction mixed with roots ofCucumis ficifolius A. Rich. taken orally
Ethiopia
[28]
Abortifacient
Seeds eaten
Ethiopia
[29, 30]
Allergies
Pounded leaves rubbed on affected body parts
Ethiopia
[20, 31]
Amoebiasis
Leaf decoction taken orally
Ethiopia
[32]
Antidote for snake and scorpion venom
Bark, ground into powder and applied to affected body part
Ethiopia
[33]
Anthrax
Root decoction taken orally
Ethiopia
[34]
Ascariasis
Bark, leaf, or root decoction taken orally
Ethiopia
[35, 36]
Atopic eczema
Leaf decoction applied to affected body part
Ethiopia
[20]
Backache
Leaf and root decoction taken orally
Kenya
[37]
Bleeding or blood coagulant
Ashes, bark, and leaf juice applied on affected body part
Ethiopia, Kenya
[31, 32, 38, 39]
Bloat
Leaf juice taken orally
Ethiopia
[26]
Cancer
Leaf and root decoction taken orally
Ethiopia, Kenya
[37, 40]
Cleansing blood circulation system
Leaf decoction taken orally
Kenya
[41]
Cleansing digestive system
Leaf decoction taken orally
Kenya
[41]
Colds
Leaf decoction taken orally
Kenya
[41]
Constipation
Fruit, leaf, or root decoction taken orally
Ethiopia, Tanzania
[16, 30]
Cough
Leaf decoction taken orally
Kenya
[41]
Dandruff
Leaf fluid applied to the head
Ethiopia
[42]
Diabetes
Root decoction taken orally
Tanzania
[43]
Diarrhoea
Bark or leaf decoction taken orally
Ethiopia, Kenya
[44–47]
Diarrhoea
Leaf decoction mixed withTrichilia spp. and Rhamnus prinoides L’Hérit. taken orally
Ethiopia
[48]
Dry cough
Leaf or root decoction taken orally
Kenya
[37]
Dysentery
Leaf decoction mixed withTrichilia spp. and Rhamnus prinoides L’Hérit. taken orally
Ethiopia
[48]
Dysentery
Bark, leaf decoction taken orally
Ethiopia
[45, 47, 49]
Dysmenorrhoea
Bark or leaf decoction taken orally
Kenya
[46]
East coast fever
Leaf and root decoction taken orally
Kenya
[37]
Eczema
Leaf decoction applied to affected body part as an ointment
Ethiopia
[17]
Epilepsy
Leaf decoction taken orally
Cameroon, Ethiopia
[36, 50]
Fungal skin infection
Leaf ointment used on affected body parts
Ethiopia
[17, 18, 20, 28, 31, 45, 47, 51]
Gonorrhoea
Bark, fruit, leaf, or root decoction taken orally
Ethiopia
[31, 34–36, 52, 53]
Gum ailment
Leaf decoction rubbed on gums
Ethiopia
[34]
Headache
Root decoction rubbed on affected part
Uganda
[54]
Hemorrhage
Leaf sap rubbed on affected part
Ethiopia
[34]
Hepatitis
Root decoction taken orally
Ethiopia
[36]
Insomnia
Leaf decoction taken orally
Cameroon
[50]
Jaundice
Leaf decoction taken orally
Ethiopia
[28]
Leprosy
Sap applied on affected body part
Ethiopia
[55, 56]
Malaria
Bark, leaf, or root decoction taken orally or smoke from burnt leaves inhaled
Ethiopia, Kenya
[26, 28, 37, 44, 55–59]
Malaria
Leaf decoction mixed withAllium sativum L. bulb roasted with butter, allowed to brew overnight and taken orally
Ethiopia
[60, 61]
Measles
Fruit, leaf, or root decoction taken orally
Ethiopia
[55, 62]
Mosquito repellent
Smoke from burnt bark or leaves repel mosquitos
Ethiopia
[38]
Obesity
Leaf and root decoction taken orally
Kenya
[37]
Pneumonia
Bark, leaf, or root decoction taken orally
Cameroon, Kenya
[37, 63]
Protection against witchcraft
Whole plant
Uganda
[64]
Purgative
Fruit, leaf, root, or seed decoction taken orally
Cameroon, Kenya, Somalia, Tanzania
[16, 37, 65, 66]
Retained placenta
Leaf infusion taken orally
Ethiopia
[56]
Rheumatism
Leaf decoction taken orally
Ethiopia
[31]
Ringworm
Bark, leaf decoction rubbed on affected body part
Ethiopia, Kenya, Tanzania
[27, 31, 38, 46, 60, 61, 67, 68]
Skin cancer
Leaf decoction applied on affected part
Ethiopia
[67]
Skin diseases
Leaf and root decoction applied on affected body parts
Ethiopia, Kenya, Tanzania
[27, 37, 55]
Skin diseases
Fruit decoction mixed withHagenia abyssinica (Bruce) J. F. Gmel. applied on affected body parts
Ethiopia
[69]
Skin rash
Mixed with egg yolk and applied to the skin
Ethiopia
[42]
Snake bite
Root decoction taken orally
Ethiopia
[70]
Sorcery
Leaf and root decoction
Kenya
[37]
Stomach ache
Bark, leaf, or root decoction taken orally
Ethiopia, Uganda
[34, 45, 49, 67, 71]
Struck by lightning
Patient bathed with leaf, fruit, and root decoction
Uganda
[54]
Tape worms
Bark decoction mixed with stems ofGlinus lotoides L. taken orally
Ethiopia
[17]
Tape worms
Leaf decoction mixed withBaccharoides calvoana subsp. meridonalis (Wild) Isawumi, El-Ghazaly & B. Nord, Vernonia auriculifera Hiern, and Salvia nilotica Juss. ex Jacq. taken orally
Rwanda
[72]
Tape worms
Bark decoction mixed withMorella salicifolia subsp. mildbraedii (Engl.) Verdc. & Polhill, Olea capensissubsp. macrocarpa (C. H. Wright) Verdc., and Elaeis guineensis Jacq. taken orally
Rwanda
[72]
Tape worms
Bark, fruit, leaf, root, or seeds decoction taken orally
Ethiopia, Tanzania, Uganda
[16, 29, 34, 35, 52, 55, 71, 73]
Typhoid
Bark, leaf, or root decoction taken orally
Cameroon, Kenya
[37, 62, 74]
Ulcers
Bark powder dressing
Ethiopia
[17]
Venereal diseases
Fruits and root decoction taken orally
Ethiopia
[29, 30]
Warts
Leaf and twig sap applied on affected body parts
Kenya
[68]
Weakness in pregnancy
Patient tie the waist with a tree branch
Uganda
[54]
Wounds
Bark, leaf, and twig sap applied directly on wounds
Ethiopia, Kenya, Tanzania
[20, 26, 27, 32, 45, 47, 55, 67, 68]
Leaf sap mixed with coconut (Cocos nucifera L.) milk and applied on wounds
Ethiopia
[44]
Leaf decoction mixed withCynoglossum lanceolatum Forssk. and Dodonaea viscosa subsp. angustifolia (L. f.) J. G. West applied on wounds
Ethiopia
[17]
Ethnoveterinary medicine
Abdominal pain
Bark decoction
Ethiopia
[75, 76]
Blackleg
Leaf decoction
Ethiopia
[44, 77]
Bleeding
Leaf decoction
Ethiopia
[21]
Bloat
Bark, leaf or twig decoction
Ethiopia
[48, 75, 76, 78]
Colic
Bark decoction
Ethiopia
[75, 76]
Constipation
Leaf decoction
Ethiopia
[77]
Dermatophilosis
Leaf decoction
Ethiopia
[21]
Epilepsy in cattle
Leaf decoction
Ethiopia
[36]
External parasites
Leaf decoction mixed withTrichilia spp. and Rhamnus prinoides L’Hérit. applied topically
Ethiopia
[48]
Fever in cows
Bark, leaf decoction
Kenya
[46]
Mange
Leaf decoction
Ethiopia
[21]
Rabies
Bark decoction mixed with leaves ofJuniperus procera Endl., stems of Eragrostis tef(Zucc.) Trotter, and roots of Cyphostemma cyphopetalum (Fresen.) Desc. ex Wild & Drummond, Solanum anguivi Lam., and Solanum marginatum L.
Ethiopia
[17]
Rabies
Root and stem bark, chewing and swallowing the juice three times a day
Ethiopia
[23, 35, 38, 48]
Rectum prolapse
Root decoction
Ethiopia
[48]
Ringworm
Leaf decoction applied directly
Ethiopia, Kenya
[21, 68, 78]
Scabies
Leaf decoction
Ethiopia
[21]
Skin diseases (dermatophilosis)
Root decoction
Ethiopia
[48]
Streptothricosis
Leaves pounded and applied on skin surface
Ethiopia
[26]
Swelling of nose in mule
Leaf decoction
Ethiopia
[36]
Tick prevention and control
Bark, leaf, or root decoction used
Kenya
[79]
Warts
Sap applied directly
Kenya
[68]
Wound
Leaf decoction applied directly
Ethiopia, Kenya
[21, 68]
Other uses
Beehives
Kenya, Tanzania
[16, 57]
Firewood
Ethiopia, Tanzania, Uganda
[16, 40, 80]
Fodder
Uganda
[80]
Pesticide
Leaves mixed withNicotiana tabacuumL. used as pesticide for maize stalk borers and aphids
Kenya
[57]
Shade
Uganda
[80]
Source of nectar
Kenya
[81]
Water pots, wood carving, tool handles, timber, stools
Cameroon, Ethiopia, Tanzania
[16, 40, 63, 65]In Cameroon, Ethiopia, Kenya, Rwanda, Somalia, Tanzania, and Uganda, leaf decoction, infusion or maceration, stem bark, or root bark ofC. macrostachyus is taken as a purgative and vermifuge (Table 1).Croton macrostachyus is also used in combination with other plant species. For example, in Ethiopia, a bark decoction ofC. macrostachyus is often mixed with roots ofCucumis ficifolius A. Rich. as remedy for abdominal pain [28]. Leaf decoction ofC. macrostachyus is often mixed with leaves ofTrichilia spp. andRhamnus prinoides L’Hérit. as remedy for diarrhoea and dysentery in humans and to repel external parasites in livestock [48]. Research by Mesfin et al. [60] and Bekele and Reddy [61] revealed that crushed leaves ofC. macrostachyus are boiled in water mixed withAllium sativum L. bulb roasted with butter; the concoction is allowed to brew overnight and taken orally the following day as remedy for malaria. For skin diseases and wounds, the fruit decoction ofC. macrostachyus is mixed with leaves ofHagenia abyssinica (Bruce) J.F.Gmel. and applied topically on affected body parts [69] while leaf sap ofC. macrostachyus is mixed with coconut (Cocos nucifera L.) milk and applied on wounds [44] or a leaf decoction mixture ofC. macrostachyus,Cynoglossum lanceolatum Forssk., andDodonaea viscosa subsp.angustifolia (L.f.) J.G.West is applied on wounds [17]. According to Teklehaymanot et al. [17], bark decoction ofC. macrostachyus is mixed with stems ofGlinus lotoides L. as herbal medicine for tapeworms while bark decoction ofC. macrostachyus is mixed with leaves ofJuniperus procera Hochst. ex Endl., stems ofEragrostis tef (Zucc.) Trotter, and roots ofCyphostemma cyphopetalum (Fresen.) Desc. ex Wild & Drummond,Solanum anguivi Lam., andSolanum marginatum L. f. as herbal medicine for rabies in Ethiopia. Research by Nahayo et al. [72] revealed that leaf decoction ofC. macrostachyus mixed with leaves ofBaccharoides calvoana subsp.meridonalis (Wild) Isawumi, El-Ghazaly & B.Nord,Vernonia auriculifera Hiern, andSalvia nilotica Juss. ex Jacq. or bark decoction ofC. macrostachyus mixed with bark ofMorella salicifolia subsp.mildbraedii (Engl.) Verdc. & Polhill,Olea capensis subsp.macrocarpa (C.H.Wright) Verdc., andElaeis guineensis Jacq. is used for worm expulsion in Rwanda. The leaves ofC. macrostachyus are used by farmers in Kenya as biological pest control when mixed with tobacco (Nicotiana tobacuum L.) and boiled overnight [57]. The resultant mixture is used as a biological pesticide for the control of maize stalk borers and aphids [57].Table1 provides a summary of ethnomedicinal uses and plant parts ofC. macrostachyus used among diverse ethnic groups in tropical Africa. In Cameroon, root decoction ofC. macrostachyus is used as purgative [65], while bark and leaf decoctions are used as remedies for epilepsy, insomnia, and typhoid [50, 63, 74]. In Ethiopia,C. macrostachyus has many uses including abdominal pain, abortifacient, amoebiasis, antidote for scorpion, and snake venom, anthrax, ascariasis, cancer, constipation, diarrhoea, dysentery, epilepsy, jaundice, leprosy, malaria, ringworm, sexually transmitted infections (STIs), skin diseases, stomach ache, tapeworms, typhoid, and wounds [17, 20, 26, 28–32, 34, 35, 38, 40, 44, 45, 49–52, 55–57, 60, 61, 63, 65, 67, 69, 72, 74, 82]. In Kenya,C. macrostachyus bark juice, leaf, and root decoction is used as remedy for backache, bleeding, cancer, colds, cough, diarrhoea, dysmenorrhoea, east coast fever, malaria, measles, obesity, pneumonia, ringworm, skin diseases, typhoid, warts, and wounds [37, 39, 46, 58, 59, 62, 68]. Research by Mazzanti et al. [66] revealed that seeds are used as purgatives in Somalia. In Tanzania, fruit and decoction ofC. macrostachyus are used as purgative [16], while fruit, leaf, and root decoctions are used as remedies for abdominal pain, constipation, diabetes, ringworm, skin infections, sores, and worm expulsion [16, 27, 43]. In Uganda,C. macrostachyus bark and root decoctions are used as remedies for headache, stomach ache, and worms [54, 71]. Bark, leaf, root, and twig decoctions ofC. macrostachyus are used as ethnoveterinary medicine in Ethiopia and Kenya for abdominal pain, blackleg, bleeding, bloat, colic, constipation, dermatophilosis, epilepsy, fever, rabies, rectum prolapsed, ringworm, scabies, skin diseases, warts, and wounds [17, 21, 23, 35, 36, 38, 44, 48, 68, 75–78].In Kenya, Tanzania, and Uganda,C. macrostachyus is commonly planted as an ornamental or shade tree in villages and the tree is also used as a shade-bearer on coffee plantations and other crops [16, 57, 80]. The wood is used in Cameroon, Ethiopia, Kenya, Tanzania, and Uganda to make tool handles, small stools, boxes, crates, and plywood, as flooring and building material and in carpentry [16, 40, 57, 63, 65, 80]. The wood is used as fuel that burns even when green but produces a rather unpleasant spicy odour and much smoke; it is also used to make charcoal [11, 16, 63, 65, 80]. Due to its drought hardiness and fast growth,Croton macrostachyus is considered useful for afforestation of shifting sand dunes, degraded waste land, hill slopes, ravines, and lateritic soils [11].


## 5. Phytochemistry

Multiple classes of phytochemicals including alkaloids, amino acids, anthraquinones, carbohydrates, cardiac glycosides, coumarins, essential oil, fatty acids, flavonoids, phenolic compounds, phlobatannins, polyphenols, phytosteroides, saponins, sterols, tannins, terpenoids, unsaturated sterol, vitamin C, and withanoides have been identified fromC. macrostachyus fruits, leaves, stem bark, and twigs [24, 30, 47, 55, 83–89]. Addae-Mensah et al. [83] isolated betulin1, lupeol2, crotepoxide3, β-sitosterol4, and stigmasterol5 from stem barks and twigs ofC. macrostachyus (see Table 2, Figure 2). Kapingu et al. [90] isolated 3β-acetoxy taraxer-14-en-28-oic acid6, trachyloban-19-oic acid7, trachyloban-18-oic acid8, neoclerodan-5,10-en-19,6β; 20,12-diolide9, 3α,19-dihydroxytrachylobane10, and 3α,18,19-trihydroxytrachylobane11 from roots ofC. macrostachyus. Tane et al. [91] isolated crotepoxide3 and crotomacrine12 from fruits ofC. macrostachyus. Tene et al. [92] isolated betulin1, lupeol2, floridolide A13, hardwickic acid14, and 12-oxo-hardwickic acid15 from stem bark ofC. macrostachyus. Tala et al. [93] isolated and identified betulin1, lupeol2, β-sitosterol4, stigmasterol5, lupenone16, betulinic acid17, 28-O-acetylbetulin18, lupeol acetate19, zeorin20, benzoic acid21, methyl gallate22, methyl 2,4-dihydroxy-3,6-dimethylbenzoate23, lichexanthone24, and β-sitosterol palmitate25 from twigs ofC. macrostachyus.Table 2
Chemical compounds isolated and characterized fromCroton macrostachyus.
Number
Compound
Plant part(s)
Reference(s)
Triterpene
1
Betulin
Stem bark, twigs
[83, 92, 93]
2
Lupeol
Stem bark, twigs
[83, 92, 93]
6
3β-Acetoxy taraxer-14-en-28-oic acid
Roots
[90]
16
Lupenone
Twigs
[93]
17
Betulinic acid
Twigs
[93]
18
28-O-Acetylbetulin
Twigs
[93]
19
Lupeol acetate
Twigs
[93]
20
Zeorin
Twigs
[93]
Cyclohexane diepoxide
3
Crotepoxide
Fruits, stem bark, twigs
[83, 91, 94]
Phytosterol
4
β-Sitosterol
Stem bark, twigs
[83, 93]
5
Stigmasterol
Stem bark, twigs
[83, 93]
25
β-Sitosterol palmitate
Twigs
[93]
Diterpenoids
7
Trachyloban-19-oic acid
Roots
[90]
8
Trachyloban-18-oic acid
Roots
[90]
9
Neoclerodan-5,10-en-19,6β;20,12-diolide
Roots
[90]
10
3α,19-Dihydroxytrachylobane
Roots
[90]
11
3α,18,19-Trihydroxytrachylobane
Roots
[90]
12
Crotomacrine
Fruits
[91]
13
Floridolide A
Stem bark
[92]
14
Hardwickic acid
Stem bark
[92]
15
12-oxo-Hardwickic acid
Stem bark
[92]
Phenolic compounds
21
Benzoic acid
Twigs
[93]
22
Methyl gallate
Twigs
[93]
23
Methyl 2,4-dihydroxy-3,6-dimethylbenzoate
Twigs
[93]
24
Lichexanthone
Twigs
[93]Figure 2
Chemical structures of major compounds isolated from leaves, roots, and stems ofCroton macrostachyus.


## 6. Pharmacological Activities

A number of pharmacological activities ofC. macrostachyus have been reported in literature justifying some of its ethnomedicinal uses listed in Table 1. These pharmacological activities include anthelmintic [30, 95], antibacterial [53, 55, 62, 85, 92, 96–100], anticonvulsant and sedative [50], antidiabetic [88], antidiarrhoeal [24], antifungal [62, 86, 92, 101], anti-inflammatory [84, 102], antileishmanial [94], antioxidant [86], antiplasmodial [87, 89, 103, 104], antimycobacterial [105], larvicidal [19, 50], and cytotoxicity [27, 43, 73, 96, 104–108].


### 6.1. Anthelmintic

Eguale et al. [30] evaluated anthelmintic activities of crude aqueous and hydroalcoholic extracts of the seeds ofC. macrostachyus on eggs and adult tapeworms(Haemonchus contortus). Both aqueous and hydroalcoholic extracts ofC. macrostachyus induced statistically significant egg hatching inhibition (p<0.05) with aqueous extract requiring maximum concentration of 0.5 mg/ml to induce 100% egg hatch inhibition while the hydroalcoholic extracts did not induce complete inhibition at highest concentration tested of 2 mg/ml. The aqueous extract ofC. macrostachyus induced 50% inhibition (ED50) at 0.10 mg/ml which was at a lower concentration than the hydroalcoholic extract at ED50 value of 0.32 mg/ml [30]. After 24 hours of exposure of adultHaemonchus contortus to different concentration of plant extracts, hydroalcoholic extracts of the species produced mortality of adultHaemonchus contortus to the level of 90% at concentration of 8 mg/ml while aqueous extract produced only 36.67% at the same concentration [30]. Similarly, Aleme et al. [95] evaluated the anthelmintic effects of crude aqueous extracts of the leaves ofC. macrostachyus against adults of liveHaemonchus contortus and the efficacy of these crude aqueous extracts was determined based on the mortality rate of the adult parasite. The efficacy at 4 mg/ml of the aqueous extracts ofC. macrostachyus was 70% against the adult stage ofHaemonchus contortus and the efficacy of the positive control, albendazole, against the adult parasite was dose-dependent and all the adult worms were dead at a concentration of 0.5 mg/ml within 24 hours [95]. These findings indicate thatC. macrostachyus has potential anthelmintic effect and could be used as an inexpensive and eco-friendly alternative to controlling tapeworm infections.


### 6.2. Antibacterial

Geyid et al. [55] evaluated antibacterial activities of methanol, petroleum ether, and aqueous fruit extracts ofC. macrostachyus againstBacillus cereus,Escherichia coli,Neisseria gonorrhoea,Salmonella typhi,Salmonella typhimurium,Shigella dysentery,Shigella flexineri,Staphylococcus aureus,Streptococcus pneumoniae, andStreptococcus pyogenes using the agar dilution method. Methanol fruit extract of C. macrostachyus inhibited growth ofNeisseria gonorrhoeae at four levels of concentration, that is, 250, 500, 1000, and 2000 μg/ml. Mesfin et al. [85] evaluated antibacterial activities of chloroform, n-butanol, and aqueous fractions ofC. macrostachyus againstNeisseria gonorrhoeae using the agar dilution method. Chloroform and n-butanol fractions ofC. macrostachyus were more active with minimum inhibitory concentration (MIC) values ranging from 125 to 250 μg/mL [85]. Wagate et al. [96] also evaluated antibacterial activities of leaf and root methanolic extracts ofC. macrostachyus againstBacillus cereus,Escherichia coli,Pseudomonas aeruginosa, andStaphylococcus aureus using the broth dilution method with benzylpenicillin and streptomycin as positive controls. The methanolic extracts ofC. macrostachyus were the most active againstBacillus cereus with minimum inhibitory concentration (MIC) value of 15.6 mg/mL and MIC value of 250 mg/mL against bothEscherichia coli andPseudomonas aeruginosa [96]. In another study, Wagate et al. [97] evaluated antibacterial activities of methanol leaf and root extracts ofC. macrostachyus againstBacillus cereus,Escherichia coli,Micrococcus lutea, andPseudomonas aeruginosa using broth dilution method with benzylpenicillin and streptomycin as positive controls.Croton macrostachyus methanol leaf and root extracts were active againstBacillus cereus with minimum inhibitory concentration (MIC) value of 15.6 mg/mL as well asEscherichia coli andPseudomonas aeruginosa, both with MIC value of 250 mg/mL [97]. Tene et al. [92] also evaluated antibacterial activities of the ethanol stem bark extract ofC. macrostachyus and five compounds isolated from the stem bark of the species, namely, betulin1, lupeol2, floridolide A13, hardwickic acid14, and 12-oxo-hardwickic acid15 againstKlebsiella pneumoniae,Salmonella typhi, andStaphylococcus aureus. The ethanol stem bark extract demonstrated some activity with the minimum bactericidal concentration (MBC) values ranging from 31.25 to 500 μg/ml; the best activity of 31.25 μg/ml was againstStaphylococcus aureus. The compounds demonstrated some activity with the minimum bactericidal concentration (MBC) values ranging from 15.62 to >1000 μg/ml. The best activity was demonstrated by betulin1 with MIC value of 15.25 μg/ml againstSalmonella typhi andStaphylococcus aureus, and MIC value of 31.25 μg/ml againstKlebsiella pneumoniae, while hardwickic acid14 had MIC value of 31.25 μg/ml againstStaphylococcus aureus and 12-oxo-hardwickic acid15 had MIC value of 62.5 μg/ml againstStaphylococcus aureus [92].Belay et al. [98] evaluated antibacterial activities of volatile fractions ofC. macrostachyus fruits againstBacillus cereus,Citrobacter spp.,Escherichia coli,Klebsiella pneumonia,Listeria monocytogenes,Proteus mirabilis,Pseudomonas aeruginosa,Salmonella paratyphi,Shigella dysenteriae,Staphylococcus aureus, andStreptococcus pyogenes using dimethyl sulfoxide (DMSO) and Tween-80 as negative controls and gentamicin as positive control. Antibacterial activity was demonstrated with minimum inhibitory concentration (MIC) values ranging from 0.1 to 12.5 μg/ml and minimum bactericidal concentration (MBC) values ranging from 0.2 to 25 μg/ml [98]. Taye et al. [99] also evaluated antibacterial activities of aqueous and methanol leaf extracts ofC. macrostachyus againstEscherichia coli,Proteus vulgaris,Pseudomonas aeuruginosa,Staphylococcus aureus, andStreptococcus pyogenes using the agar well diffusion method with ciprofloxacin and amoxicillin as positive controls. Antibacterial activity was demonstrated by methanol leaf extract againstStreptococcus pyogenes with minimum bacterial concentration (MBC) value of 7.81 mg/mL. Mesfin et al. [53] also evaluated antibacterial activities of chloroform, n-butanol, and aqueous leaf extracts ofC. macrostachyus againstNeisseria gonorrhoeae using the agar dilution method. Chloroform and n-butanol fractions were identified to be more active with minimum inhibitory concentration (MIC) values between 125 and 250 μg/ml [53]. Similarly, Sendeku et al. [100] evaluated antibacterial activities of chloroform, ethanol and methanol leaf extracts ofC. macrostachyus using the agar well diffusion and broth dilution assay methods againstEscherichia coli,Klebsiella pneumonia,Salmonella pneumonia,Shigella flexneri, andStaphylococcus aureus. The leaf extract showed some activity with minimum inhibitory concentrations (MIC) varying from 3.75 to 30.0 mg/ml and minimum bactericidal concentrations (MBC) varying from 7.5 to 40.0 mg/ml [100]. Recently, Obey et al. [62] evaluated antibacterial activities of methanol, ethyl acetate, and butanol stem bark extracts and purified lupeol2 isolated fromC. macrostachyus againstEscherichia coli,Salmonella typhi,Klebsiella pneumoniae,Enterobacter aerogenes, andListeria monocytogenes using the agar well diffusion method. The most promising broad scale antibacterial activity against all the studied pathogens was shown by the ethyl acetate extract with minimum inhibitory concentrations (MICs) ranging from 125 to 250 mg/mL and lupeol 2 had the lowest MIC value of 125 mg/mL againstKlebsiella pneumoniae. These antibacterial activities displayed by different extracts [53, 55, 62, 85, 92, 96–100] somehow confirm the potential ofC. macrostachyus in the treatment and management of bacterial infections as detailed in Table 1.


### 6.3. Antimycobacterial

Gemechu et al. [105] evaluated antimycobacterial activities of methanolic leaf extracts ofC. macrostachyus againstMycobacterium tuberculosis andMycobacterium bovis strains using 96 wells of microplate with the help of visual Resazurin Microtiter assay. The methanolic leaf extracts ofC. macrostachyus demonstrated antimycobacterial activity with minimum inhibitory concentration (MIC) values ranging from 12.5 to 100 μg/mL. The results of this study demonstrate thatC. macrostachyus has potential as herbal medicine in the treatment and management of tuberculosis, a leading cause of death in sub-Saharan Africa [109]. However, further investigations are needed aimed at identifying chemical constituents ofC. macrostachyus responsible for these activities and their mode of action.


### 6.4. Antifungal

Tene et al. [92] evaluated antifungal activities of the ethanol stem bark extract ofC. macrostachys and chemical compounds isolated from the stem bark of the species, namely, betulin1, lupeol2, floridolide A13, hardwickic acid14, and 12-oxo-hardwickic acid15 againstCandida albicans,Candida krusei, andCryptococcus neoformans. The ethanol stem bark extract demonstrated some activity with the minimum fungicidal concentration (MFC) values ranging from 62.5 to 1000 μg/ml, and the best activity of 62.5 μg/ml was againstCandida albicans. The compounds demonstrated some activity with the minimum fungicidal concentration (MFC) values ranging from 7.81 to >1000 μg/ml. The best activity was demonstrated by 12-oxo-hardwickic acid15 with MIC value of 7.81 μg/ml againstCandida albicans, MIC value of 31.25 μg/ml againstCandida krusei andCryptococcus neoformans, and hardwickic acid14 had MIC value of 62.5 μg/ml againstCandida albicans [92]. Abera et al. [101] also evaluated antifungal activity of aqueous and ethanol extracts ofC. macrostachyus againstColletotrichum kahawae, a fungus that causes coffee berry disease.Croton macrostachyus aqueous and ethanol extracts reduced radial growth ofColletotrichum kahawae in ethanol and aqueous extracts by 68% and 88%, respectively. This study indicated the possible use ofC. macrostachyus extracts as an alternative means of coffee berry disease management [101]. Teugwa et al. [86] evaluated antifungal activities of aqueous and methanol leaf extracts ofC. macrostachyus againstTrichophyton rubrum,Trichophyton soudanense, andTrichophyton violaceum using the agar dilution method with amphotericin as positive control. All extracts tested showed antifungal activity against the threeTrichophyton species tested, with minimum inhibitory concentration (MIC) and minimum fungicidal concentrations (MFC) varying from 17.50 to 27.50 and 20 to 30 mg/ml, respectively. Recently, Obey et al. [62] evaluated antifungal activities of methanol, ethyl acetate, and butanol stem bark extracts and purified lupeol 2 isolated fromC. macrostachyus againstCandida albicans using the agar well diffusion method. The most promising broad scale antifungal activity was shown by the ethyl acetate extract with minimum inhibitory concentrations (MICs) of 500 mg/mL and lupeol2 had MIC value of 500 mg/mL [62].


### 6.5. Antidiarrhoeal

Degu et al. [24] evaluated the antidiarrheal activities of chloroform and methanol leaf extracts ofC. macrostachyus using the castor oil induced diarrheal model, charcoal meal test and antienteropooling test in mice. The test groups received various doses (300, 400, and 500 mg/kg and an additional dose of 1000 mg/kg for the aqueous fraction) of the fractions, whereas positive controls received either loperamide (3 mg/kg) or atropine (5 mg/kg) and negative controls received vehicle (10 ml/kg). In the castor oil induced model, the chloroform (at all test doses) and methanol (at 400 and 500 mg/kg) fractions delayed diarrheal onset and decreased stool frequency and weight of faeces. The chloroform and methanol fractions produced dose-dependent decline in the weight and volume of intestinal contents while the aqueous fraction did not have a significant effect [24]. These authors also found that all the fractions produced antimotility effect either at all doses (chloroform fraction) or at middle and higher doses (methanol and aqueous fractions).


### 6.6. Anticonvulsant and Sedative

Bum et al. [50] evaluated anticonvulsant effects of crude extracts ofC. macrostachyus using mice model (maximal electroshock (MES), strychnine (STR), pentylenetetrazol (PTZ), picrotoxin (PIC), isonicotinic hydrazide acid (INH))-induced convulsions and diazepam-induced sleep in assessing the sedative effects.Croton macrostachyus at the doses of 34 and 67 mg/kg protected 80, 80, 80, and 60% of mice from PIC, STR, PTZ, and MES-induced seizures, respectively [50].Croton macrostachyus also delayed the onset to seizures in the INH test. The decoctions ofC. macrostachyus possess sedative and anticonvulsant activities and these results corroborate the use of the species as herbal medicine for epilepsy in Ethiopia [36] and epilepsy and insomnia in Cameroon [50].


### 6.7. Antidiabetic

Arika et al. [88] evaluatedin vivo hypoglycemic activity of aqueous leaf extracts ofC. macrostachyus in male Swiss white albino mice. Aqueous leaf extract ofC. macrostachyus was intraperitoneally and orally administered to alloxan (180.9 mg/kg; intraperitoneally) induced diabetic mice at different doses of 25 mg/kg body weight (bwt), 48.4 mg/kg bwt, 93.5 mg/kg bwt, 180.9 mg/kg bwt, and 350 mg/kg bwt and the effects on blood glucose levels investigated. Treatment of diabetic mice with doses of the leaf extract resulted in significantly lower levels of fasting blood glucose and the effects of the leaf extract were comparable with the conventional drugs [88]. Therefore, the results suggest thatC. macrostachyus leaf extract is a potent hypoglycemic agent and this validates the use of root decoction as herbal medicine for diabetes in Tanzania [43].


### 6.8. Anti-Inflammatory

Kamanyi et al. [84] evaluated the antinociceptive and anti-inflammatory activities of the aqueous and methylene chloride/methanol stem bark extracts ofC. macrostachyus. The extracts were administered orally at the doses of 150, 300, and 600 mg/kg and examined against pain induced by acetic acid, formalin, and pressure and against inflammation induced by carrageenan, histamine, and formalin. Results obtained by Kamanyi et al. [84] showed that both extracts induced dose-dependent reduction in the number of abdominal constrictions induced by acetic acid, and the three doses of the two extracts also reduced the two phases of pain induced by formalin. At the dose of 600 mg/kg, the aqueous and the methylene chloride/methanol extracts exhibited analgesic activity against pressure-induced pain. The two extracts also exhibited anti-inflammatory activity, the methylene chloride/methanol extract being the most active inhibited acute inflammation induced by carrageenan, histamine, and formalin, and both extracts reduced the chronic inflammation induced by formalin [84]. Nguelefack et al. [102] also evaluated the antinociceptive properties of the methanol/methylene chloride extracts of the stem bark ofC. macrostachyus using mice models of persistent inflammatory and neuropathic pain and also assessed its mechanism of action. The methanol/methylene chloride extract was tested on Complete Freund Adjuvant- (CFA-) induced persistent thermal and mechanical pain, neuropathic pain induced by partial sciatic nerve ligation (PSNL), prostaglandin E2- (PGE2-) induced acute mechanical hyperalgesia, as well as on nociception induced by capsaicin in mice. Mechanical hyperalgesia was assessed using von Frey hair in awake mice. The mechanism of action of methanol/methylene chloride extract was evaluated by using glibenclamide on PGE2-induced hyperalgesia or rimonabant on capsaicin-induced pain [102]. The authors found that the methanol/methylene chloride extract administered orally at the doses of 250 and 500 mg/kg induced long lasting and significant antihyperalgesic effects on CFA-inflammatory and PSNL-induced neuropathic pain. The methanol/methylene chloride extract significantly reduced the mechanical hyperalgesia induced by PGE2 either when administered preventively or therapeutically [102]. The authors also found that the methanol/methylene chloride extract also significantly and time dependently inhibited the capsaicin-induced nociception. These studies show thatC. macrostachyus extracts of the stem bark possess analgesic, anti-inflammatory, and antinociceptive properties corroborating the traditional use of the species in the treatment and management of different diseases and ailments, including pain and inflammation in tropical Africa.


### 6.9. Antileishmanial

Gelaw et al. [94] evaluated the antileishmanial activities of a compound, crotepoxide 3 isolated from chloroform extracts ofC. macrostachyus against promastigotes and amastigotes form ofLeishmania aethiopica. The result of the study revealed that observed IC50 values of crotepoxide 3 to be 219.7 and 229.70 μg/ml against promastigotes and amastigotes, respectively, and therefore, less active when compared to the reference antileishmanial drugs amphotericin B and miltefosine with IC50 values of 0.03 and 0.12 μg/ml, respectively [94].


### 6.10. Antioxidant

Teugwa et al. [86] evaluated antioxidant activities of methanolic leaf extracts ofC. macrostachyus using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging methods. Methanolic leaf extract ofC. macrostachyus showed antioxidant activity with IC50 value of 0.11 mg/ml. The documented antioxidant activities ofC. macrostachyus leaf extracts are probably due to flavonoids and phenols that have been isolated from fruits, leaves, and roots [24, 30, 47, 51, 55, 84–89, 93]. Flavonoids and phenolic compounds found in plants are known to have antioxidant properties [110].


### 6.11. Antiplasmodial

Owuor et al. [103] evaluated antiplasmodial activities of dichloromethane leaf and stem extracts ofC. macrostachyus using the SYBR Green I fluorescence assay (MSF assay) with mefloquine and chloroquine as positive controls. The dichloromethane leaf and stem extracts were active against chloroquine sensitivePlasmodium falciparum strain with IC50 value of 2.720±0.627 μg/ml [103]. Similarly, Bantie et al. [87] evaluated antiplasmodial activities of chloroform, methanol, and aqueous leaf extracts ofC. macrostachyus using a rodent model of malaria. The rodent malaria parasitePlasmodium berghei was used to inoculate healthy male Swiss albino mice, 6–8 weeks old, and the parameters parasitemia, survival time, body weight, temperature, and packed cell volume were then determined using Peter’s and Rane’s tests [87]. Chemoprotective effect exerted by the extracts ranged between 12 and 91% and the chemotherapeutic effect of the extracts was in the range of 39–83%. The crude extracts prevented loss of weight and reduction in temperature but did not affect packed cell volume [87]. In another study, Mohammed et al. [104] evaluated antimalarial activities of the methanol and aqueous leaf extracts ofC. macrostachyus using a 4-day suppressive standard test onPlasmodium berghei. Methanol and aqueous extracts ofC. macrostachyus showed dose-dependent chemosuppressive effect at various doses in mice infected withPlasmodium berghei parasite while the crude methanol extracts ofC. macrostachyus suppressed parasitaemia at all dose levels compared to the negative control groups but did not improve survival time [104]. The mice treated with the methanol and aqueous extracts at 600 mg/kg survived longer (10.60±0.51 days for methanol extract and 9.60±0.51 day for aqueous extract) than those in the negative control group with mean survival time of 6.2±0.20 days [104]. The antimalarial activity test showed thatC. macrostachyus exhibited significant antiplasmodial activity as evidenced by their ability to suppressPlasmodium berghei infection in mice in a dose-dependent manner, which may partly justify the claim by traditional practitioners about the use of these two plants against malaria. Mekonnen [89] also evaluated antiplasmodial activity of 80% methanol extract of the fruit and root ofC. macrostachyus in a rodent model of malaria. The rodent malaria parasitePlasmodium berghei was used to inoculate healthy 8-week-old male Swiss albino mice and the parameters of parasitemia, survival time, body weight, temperature, and packed cell volume were determined using Peter’s test and Rane’s test [89]. Both extracts significantly inhibited parasitemia, increased survival time, prevented loss of weight and temperature, but did not affect the packed cell volume [89]. Results of this study suggest that the root and fruit extracts ofC. macrostachyus have promising antiplasmodial activity againstPlasmodium berghei in a dose-dependent manner, which supports the folkloric use of the plant for treating malaria.


### 6.12. Larvicidal

Karunamoorthi and Ilango [19] evaluated larvicidal activities of methanol leaf extracts ofC. macrostachyus against late third instar larvae ofAnopheles arabiensis Patton, a potent malaria vector. The larval mortality was observed 24 h of posttreatment. The methanol leaf extracts showed different degree of mortality against the malaria vectorAnopheles arabiensis with LC50 and LC90 values of 89.25 and 224.98 ppm, respectively. These results establish thatC. macrostachyus could serve as potent mosquito larvicidal agent againstAnopheles arabiensis although its mode of actions and larvicidal efficiency under the field conditions should be investigated and determined.


### 6.13. Toxicity

The results of toxicity studies of aqueous and hydroalcoholic bark extracts ofC. macrostachyus using albino mice showed LD50 value of 190.2±15.7 mg/kg for aqueous extract and LD50 value of 87.5±12.3 mg/kg for hydroalcoholic extract [73]. Desta [73] determined the median effective single dose ofC. macrostachyus bark extract, that is, the dose that expelledTaenia saginata L. worms partially or totally in 50% of worm-infested human volunteers.Croton macrostachyus showed median effective single dose of 6.42±0.82 and the number of hours that elapsed before partial or total expulsion of the worms following administration ofC. macrostachyus was 12.9±2.1 hours. Gadir et al. [106] evaluated oral toxicity ofC. macrostachyus seeds in Nubian goat kids through clinical, hematological, and pathophysiological parameters. The Nubian goat kids were allotted as untreated controls and groundC. macrostachyus seeds were given to kids in repeated daily oral doses of 1 g/kg or 0.25 g/kg. Both oral dose levels ofC. macrostachyus seeds were lethal for kids between days 7 and 21 and caused bloody diarrhoea, dyspnea, dehydration, loss in condition, paresis of the hind limbs, and recumbency before death [106]. Lesions in the affected animals included widespread hemorrhages and congestion, enterohepatonephrotoxicity, pulmonary hemorrhage, emphysema and cyanosis, tracheal froths, ascites, and hydropericardium. These lesions were accompanied by increases in the activity of serum AST, in the concentration of urea, and decreases in total protein and albumin, anemia, and leukopenia [106]. Moshi et al. [43] evaluated toxicity of root aqueous ethanol extracts ofC. macrostachyus using the brine shrimp lethality test.Croton macrostachyus demonstrated moderate toxicity with concentration killing 50% (LC50) of the shrimps at 13.40 μg/ml. These findings indicate the possibility thatC. macrostachyus extracts may be toxic or contain useful cytotoxic compounds, which were not reported by the traditional healers. Wagate et al. [96] evaluated cytotoxicity of leaf and root methanolic extracts ofC. macrostachyus using the brine shrimp lethality test.Croton macrostachyus showed LC50 value of 387 μg/mL, which was considered to be relatively nontoxic [96].Mbiantcha et al. [107] evaluated toxicity of aqueous and methylene chloride/methanol extracts of C.macrostachyus stem bark usingArtemia spp. lethality assay, mice and Wistar rats. For the cytotoxicity study, the aqueous and organic extracts were administered to larvae ofArtemia spp. and the number of deaths was determined after 6 hours and 24 hours, while for the acute study, the extracts were administered to mice. In the cytotoxicity study, aqueous and organic extracts showed LC50 values of 569 and 425 μg/ml, respectively. In acute toxicity study, aqueous extract did not provoke death until the dose 16 g/kg, whereas the organic extract caused general behaviors, adverse effects, and mortality. Mortality increased with increasing doses, with LD50 values of 10.2 and 9.4 g/kg bwt, respectively, for male and female mice [107]. In another acute toxicity study in mice, the methanol leaf extract ofC. macrostachyus at a single oral doses of 2 and 5 g/kg bwt caused no mortality within the first 24 h and up to 14 days observation period [87]. Results from the study suggested safety profile of this herbal extract in the study mice. Physical and behavioral observations of the experimental mice did not show any visible signs of overt toxicity such as lacrimation, loss of appetite, tremors, hair erection, salivation, and diarrhoea. These studies revealed thatC. macrostachyus is not toxic in both acute and subacute tests at the tested doses of the extracts. In anin vivo study, the methanol extract ofC. macrostachyus showed dose-dependent chemosuppressive effect at various dose levels, that is, 200 (21.1%), 400 (27.7%), and 600 (34.3%) mg/kg body weight inPlasmodium berghei-infected mice [104]. The mice treated with chloroquine were completely free from parasitemia on day 4 in all groups (100% suppression). The crude methanol extract ofC. macrostachyus significantly suppressed parasitemia at all dose levels compared to the negative control groups (distilled water) but did not significantly prolong the survival time of infected mice. Similarly, the aqueous extract at the doses of 200, 400, and 600 mg/kg body weight significantly reduced % parasitemia (26.14, 30.50, and 50.53%, resp.) compared to the negative control group in this study. Mbunde et al. [27] evaluated toxicity of leaf dichloromethane extracts ofC. macrostachyus using the brine shrimp lethality test.Croton macrostachyus demonstrated moderate toxicity with concentration killing 50% (LC50) of the shrimps at 12.94 μg/ml [27]. Omosa et al. [108] also evaluated the cytotoxicity of dichloromethane and methanol (1 : 1) extract ofC. macrostachyus stem bark using the resazurin reduction assay against CCRF-CEM leukemia cell line. The dichloromethane and methanol extract ofC. macrostachyus stem bark displayed cytotoxicity towards leukemia CCRF-CEM cells with IC50 value of 60.6 μg/mL [108]. Based on the cytotoxicity studies done on C. macrostachyus crude extracts [27, 43, 73, 96, 104, 106–108], it can be concluded that caution must be exercised in the use of the species as herbal medicine.


## 6.1. Anthelmintic

Eguale et al. [30] evaluated anthelmintic activities of crude aqueous and hydroalcoholic extracts of the seeds ofC. macrostachyus on eggs and adult tapeworms(Haemonchus contortus). Both aqueous and hydroalcoholic extracts ofC. macrostachyus induced statistically significant egg hatching inhibition (p<0.05) with aqueous extract requiring maximum concentration of 0.5 mg/ml to induce 100% egg hatch inhibition while the hydroalcoholic extracts did not induce complete inhibition at highest concentration tested of 2 mg/ml. The aqueous extract ofC. macrostachyus induced 50% inhibition (ED50) at 0.10 mg/ml which was at a lower concentration than the hydroalcoholic extract at ED50 value of 0.32 mg/ml [30]. After 24 hours of exposure of adultHaemonchus contortus to different concentration of plant extracts, hydroalcoholic extracts of the species produced mortality of adultHaemonchus contortus to the level of 90% at concentration of 8 mg/ml while aqueous extract produced only 36.67% at the same concentration [30]. Similarly, Aleme et al. [95] evaluated the anthelmintic effects of crude aqueous extracts of the leaves ofC. macrostachyus against adults of liveHaemonchus contortus and the efficacy of these crude aqueous extracts was determined based on the mortality rate of the adult parasite. The efficacy at 4 mg/ml of the aqueous extracts ofC. macrostachyus was 70% against the adult stage ofHaemonchus contortus and the efficacy of the positive control, albendazole, against the adult parasite was dose-dependent and all the adult worms were dead at a concentration of 0.5 mg/ml within 24 hours [95]. These findings indicate thatC. macrostachyus has potential anthelmintic effect and could be used as an inexpensive and eco-friendly alternative to controlling tapeworm infections.


## 6.2. Antibacterial

Geyid et al. [55] evaluated antibacterial activities of methanol, petroleum ether, and aqueous fruit extracts ofC. macrostachyus againstBacillus cereus,Escherichia coli,Neisseria gonorrhoea,Salmonella typhi,Salmonella typhimurium,Shigella dysentery,Shigella flexineri,Staphylococcus aureus,Streptococcus pneumoniae, andStreptococcus pyogenes using the agar dilution method. Methanol fruit extract of C. macrostachyus inhibited growth ofNeisseria gonorrhoeae at four levels of concentration, that is, 250, 500, 1000, and 2000 μg/ml. Mesfin et al. [85] evaluated antibacterial activities of chloroform, n-butanol, and aqueous fractions ofC. macrostachyus againstNeisseria gonorrhoeae using the agar dilution method. Chloroform and n-butanol fractions ofC. macrostachyus were more active with minimum inhibitory concentration (MIC) values ranging from 125 to 250 μg/mL [85]. Wagate et al. [96] also evaluated antibacterial activities of leaf and root methanolic extracts ofC. macrostachyus againstBacillus cereus,Escherichia coli,Pseudomonas aeruginosa, andStaphylococcus aureus using the broth dilution method with benzylpenicillin and streptomycin as positive controls. The methanolic extracts ofC. macrostachyus were the most active againstBacillus cereus with minimum inhibitory concentration (MIC) value of 15.6 mg/mL and MIC value of 250 mg/mL against bothEscherichia coli andPseudomonas aeruginosa [96]. In another study, Wagate et al. [97] evaluated antibacterial activities of methanol leaf and root extracts ofC. macrostachyus againstBacillus cereus,Escherichia coli,Micrococcus lutea, andPseudomonas aeruginosa using broth dilution method with benzylpenicillin and streptomycin as positive controls.Croton macrostachyus methanol leaf and root extracts were active againstBacillus cereus with minimum inhibitory concentration (MIC) value of 15.6 mg/mL as well asEscherichia coli andPseudomonas aeruginosa, both with MIC value of 250 mg/mL [97]. Tene et al. [92] also evaluated antibacterial activities of the ethanol stem bark extract ofC. macrostachyus and five compounds isolated from the stem bark of the species, namely, betulin1, lupeol2, floridolide A13, hardwickic acid14, and 12-oxo-hardwickic acid15 againstKlebsiella pneumoniae,Salmonella typhi, andStaphylococcus aureus. The ethanol stem bark extract demonstrated some activity with the minimum bactericidal concentration (MBC) values ranging from 31.25 to 500 μg/ml; the best activity of 31.25 μg/ml was againstStaphylococcus aureus. The compounds demonstrated some activity with the minimum bactericidal concentration (MBC) values ranging from 15.62 to >1000 μg/ml. The best activity was demonstrated by betulin1 with MIC value of 15.25 μg/ml againstSalmonella typhi andStaphylococcus aureus, and MIC value of 31.25 μg/ml againstKlebsiella pneumoniae, while hardwickic acid14 had MIC value of 31.25 μg/ml againstStaphylococcus aureus and 12-oxo-hardwickic acid15 had MIC value of 62.5 μg/ml againstStaphylococcus aureus [92].Belay et al. [98] evaluated antibacterial activities of volatile fractions ofC. macrostachyus fruits againstBacillus cereus,Citrobacter spp.,Escherichia coli,Klebsiella pneumonia,Listeria monocytogenes,Proteus mirabilis,Pseudomonas aeruginosa,Salmonella paratyphi,Shigella dysenteriae,Staphylococcus aureus, andStreptococcus pyogenes using dimethyl sulfoxide (DMSO) and Tween-80 as negative controls and gentamicin as positive control. Antibacterial activity was demonstrated with minimum inhibitory concentration (MIC) values ranging from 0.1 to 12.5 μg/ml and minimum bactericidal concentration (MBC) values ranging from 0.2 to 25 μg/ml [98]. Taye et al. [99] also evaluated antibacterial activities of aqueous and methanol leaf extracts ofC. macrostachyus againstEscherichia coli,Proteus vulgaris,Pseudomonas aeuruginosa,Staphylococcus aureus, andStreptococcus pyogenes using the agar well diffusion method with ciprofloxacin and amoxicillin as positive controls. Antibacterial activity was demonstrated by methanol leaf extract againstStreptococcus pyogenes with minimum bacterial concentration (MBC) value of 7.81 mg/mL. Mesfin et al. [53] also evaluated antibacterial activities of chloroform, n-butanol, and aqueous leaf extracts ofC. macrostachyus againstNeisseria gonorrhoeae using the agar dilution method. Chloroform and n-butanol fractions were identified to be more active with minimum inhibitory concentration (MIC) values between 125 and 250 μg/ml [53]. Similarly, Sendeku et al. [100] evaluated antibacterial activities of chloroform, ethanol and methanol leaf extracts ofC. macrostachyus using the agar well diffusion and broth dilution assay methods againstEscherichia coli,Klebsiella pneumonia,Salmonella pneumonia,Shigella flexneri, andStaphylococcus aureus. The leaf extract showed some activity with minimum inhibitory concentrations (MIC) varying from 3.75 to 30.0 mg/ml and minimum bactericidal concentrations (MBC) varying from 7.5 to 40.0 mg/ml [100]. Recently, Obey et al. [62] evaluated antibacterial activities of methanol, ethyl acetate, and butanol stem bark extracts and purified lupeol2 isolated fromC. macrostachyus againstEscherichia coli,Salmonella typhi,Klebsiella pneumoniae,Enterobacter aerogenes, andListeria monocytogenes using the agar well diffusion method. The most promising broad scale antibacterial activity against all the studied pathogens was shown by the ethyl acetate extract with minimum inhibitory concentrations (MICs) ranging from 125 to 250 mg/mL and lupeol 2 had the lowest MIC value of 125 mg/mL againstKlebsiella pneumoniae. These antibacterial activities displayed by different extracts [53, 55, 62, 85, 92, 96–100] somehow confirm the potential ofC. macrostachyus in the treatment and management of bacterial infections as detailed in Table 1.


## 6.3. Antimycobacterial

Gemechu et al. [105] evaluated antimycobacterial activities of methanolic leaf extracts ofC. macrostachyus againstMycobacterium tuberculosis andMycobacterium bovis strains using 96 wells of microplate with the help of visual Resazurin Microtiter assay. The methanolic leaf extracts ofC. macrostachyus demonstrated antimycobacterial activity with minimum inhibitory concentration (MIC) values ranging from 12.5 to 100 μg/mL. The results of this study demonstrate thatC. macrostachyus has potential as herbal medicine in the treatment and management of tuberculosis, a leading cause of death in sub-Saharan Africa [109]. However, further investigations are needed aimed at identifying chemical constituents ofC. macrostachyus responsible for these activities and their mode of action.


## 6.4. Antifungal

Tene et al. [92] evaluated antifungal activities of the ethanol stem bark extract ofC. macrostachys and chemical compounds isolated from the stem bark of the species, namely, betulin1, lupeol2, floridolide A13, hardwickic acid14, and 12-oxo-hardwickic acid15 againstCandida albicans,Candida krusei, andCryptococcus neoformans. The ethanol stem bark extract demonstrated some activity with the minimum fungicidal concentration (MFC) values ranging from 62.5 to 1000 μg/ml, and the best activity of 62.5 μg/ml was againstCandida albicans. The compounds demonstrated some activity with the minimum fungicidal concentration (MFC) values ranging from 7.81 to >1000 μg/ml. The best activity was demonstrated by 12-oxo-hardwickic acid15 with MIC value of 7.81 μg/ml againstCandida albicans, MIC value of 31.25 μg/ml againstCandida krusei andCryptococcus neoformans, and hardwickic acid14 had MIC value of 62.5 μg/ml againstCandida albicans [92]. Abera et al. [101] also evaluated antifungal activity of aqueous and ethanol extracts ofC. macrostachyus againstColletotrichum kahawae, a fungus that causes coffee berry disease.Croton macrostachyus aqueous and ethanol extracts reduced radial growth ofColletotrichum kahawae in ethanol and aqueous extracts by 68% and 88%, respectively. This study indicated the possible use ofC. macrostachyus extracts as an alternative means of coffee berry disease management [101]. Teugwa et al. [86] evaluated antifungal activities of aqueous and methanol leaf extracts ofC. macrostachyus againstTrichophyton rubrum,Trichophyton soudanense, andTrichophyton violaceum using the agar dilution method with amphotericin as positive control. All extracts tested showed antifungal activity against the threeTrichophyton species tested, with minimum inhibitory concentration (MIC) and minimum fungicidal concentrations (MFC) varying from 17.50 to 27.50 and 20 to 30 mg/ml, respectively. Recently, Obey et al. [62] evaluated antifungal activities of methanol, ethyl acetate, and butanol stem bark extracts and purified lupeol 2 isolated fromC. macrostachyus againstCandida albicans using the agar well diffusion method. The most promising broad scale antifungal activity was shown by the ethyl acetate extract with minimum inhibitory concentrations (MICs) of 500 mg/mL and lupeol2 had MIC value of 500 mg/mL [62].


## 6.5. Antidiarrhoeal

Degu et al. [24] evaluated the antidiarrheal activities of chloroform and methanol leaf extracts ofC. macrostachyus using the castor oil induced diarrheal model, charcoal meal test and antienteropooling test in mice. The test groups received various doses (300, 400, and 500 mg/kg and an additional dose of 1000 mg/kg for the aqueous fraction) of the fractions, whereas positive controls received either loperamide (3 mg/kg) or atropine (5 mg/kg) and negative controls received vehicle (10 ml/kg). In the castor oil induced model, the chloroform (at all test doses) and methanol (at 400 and 500 mg/kg) fractions delayed diarrheal onset and decreased stool frequency and weight of faeces. The chloroform and methanol fractions produced dose-dependent decline in the weight and volume of intestinal contents while the aqueous fraction did not have a significant effect [24]. These authors also found that all the fractions produced antimotility effect either at all doses (chloroform fraction) or at middle and higher doses (methanol and aqueous fractions).


## 6.6. Anticonvulsant and Sedative

Bum et al. [50] evaluated anticonvulsant effects of crude extracts ofC. macrostachyus using mice model (maximal electroshock (MES), strychnine (STR), pentylenetetrazol (PTZ), picrotoxin (PIC), isonicotinic hydrazide acid (INH))-induced convulsions and diazepam-induced sleep in assessing the sedative effects.Croton macrostachyus at the doses of 34 and 67 mg/kg protected 80, 80, 80, and 60% of mice from PIC, STR, PTZ, and MES-induced seizures, respectively [50].Croton macrostachyus also delayed the onset to seizures in the INH test. The decoctions ofC. macrostachyus possess sedative and anticonvulsant activities and these results corroborate the use of the species as herbal medicine for epilepsy in Ethiopia [36] and epilepsy and insomnia in Cameroon [50].


## 6.7. Antidiabetic

Arika et al. [88] evaluatedin vivo hypoglycemic activity of aqueous leaf extracts ofC. macrostachyus in male Swiss white albino mice. Aqueous leaf extract ofC. macrostachyus was intraperitoneally and orally administered to alloxan (180.9 mg/kg; intraperitoneally) induced diabetic mice at different doses of 25 mg/kg body weight (bwt), 48.4 mg/kg bwt, 93.5 mg/kg bwt, 180.9 mg/kg bwt, and 350 mg/kg bwt and the effects on blood glucose levels investigated. Treatment of diabetic mice with doses of the leaf extract resulted in significantly lower levels of fasting blood glucose and the effects of the leaf extract were comparable with the conventional drugs [88]. Therefore, the results suggest thatC. macrostachyus leaf extract is a potent hypoglycemic agent and this validates the use of root decoction as herbal medicine for diabetes in Tanzania [43].


## 6.8. Anti-Inflammatory

Kamanyi et al. [84] evaluated the antinociceptive and anti-inflammatory activities of the aqueous and methylene chloride/methanol stem bark extracts ofC. macrostachyus. The extracts were administered orally at the doses of 150, 300, and 600 mg/kg and examined against pain induced by acetic acid, formalin, and pressure and against inflammation induced by carrageenan, histamine, and formalin. Results obtained by Kamanyi et al. [84] showed that both extracts induced dose-dependent reduction in the number of abdominal constrictions induced by acetic acid, and the three doses of the two extracts also reduced the two phases of pain induced by formalin. At the dose of 600 mg/kg, the aqueous and the methylene chloride/methanol extracts exhibited analgesic activity against pressure-induced pain. The two extracts also exhibited anti-inflammatory activity, the methylene chloride/methanol extract being the most active inhibited acute inflammation induced by carrageenan, histamine, and formalin, and both extracts reduced the chronic inflammation induced by formalin [84]. Nguelefack et al. [102] also evaluated the antinociceptive properties of the methanol/methylene chloride extracts of the stem bark ofC. macrostachyus using mice models of persistent inflammatory and neuropathic pain and also assessed its mechanism of action. The methanol/methylene chloride extract was tested on Complete Freund Adjuvant- (CFA-) induced persistent thermal and mechanical pain, neuropathic pain induced by partial sciatic nerve ligation (PSNL), prostaglandin E2- (PGE2-) induced acute mechanical hyperalgesia, as well as on nociception induced by capsaicin in mice. Mechanical hyperalgesia was assessed using von Frey hair in awake mice. The mechanism of action of methanol/methylene chloride extract was evaluated by using glibenclamide on PGE2-induced hyperalgesia or rimonabant on capsaicin-induced pain [102]. The authors found that the methanol/methylene chloride extract administered orally at the doses of 250 and 500 mg/kg induced long lasting and significant antihyperalgesic effects on CFA-inflammatory and PSNL-induced neuropathic pain. The methanol/methylene chloride extract significantly reduced the mechanical hyperalgesia induced by PGE2 either when administered preventively or therapeutically [102]. The authors also found that the methanol/methylene chloride extract also significantly and time dependently inhibited the capsaicin-induced nociception. These studies show thatC. macrostachyus extracts of the stem bark possess analgesic, anti-inflammatory, and antinociceptive properties corroborating the traditional use of the species in the treatment and management of different diseases and ailments, including pain and inflammation in tropical Africa.


## 6.9. Antileishmanial

Gelaw et al. [94] evaluated the antileishmanial activities of a compound, crotepoxide 3 isolated from chloroform extracts ofC. macrostachyus against promastigotes and amastigotes form ofLeishmania aethiopica. The result of the study revealed that observed IC50 values of crotepoxide 3 to be 219.7 and 229.70 μg/ml against promastigotes and amastigotes, respectively, and therefore, less active when compared to the reference antileishmanial drugs amphotericin B and miltefosine with IC50 values of 0.03 and 0.12 μg/ml, respectively [94].


## 6.10. Antioxidant

Teugwa et al. [86] evaluated antioxidant activities of methanolic leaf extracts ofC. macrostachyus using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging methods. Methanolic leaf extract ofC. macrostachyus showed antioxidant activity with IC50 value of 0.11 mg/ml. The documented antioxidant activities ofC. macrostachyus leaf extracts are probably due to flavonoids and phenols that have been isolated from fruits, leaves, and roots [24, 30, 47, 51, 55, 84–89, 93]. Flavonoids and phenolic compounds found in plants are known to have antioxidant properties [110].


## 6.11. Antiplasmodial

Owuor et al. [103] evaluated antiplasmodial activities of dichloromethane leaf and stem extracts ofC. macrostachyus using the SYBR Green I fluorescence assay (MSF assay) with mefloquine and chloroquine as positive controls. The dichloromethane leaf and stem extracts were active against chloroquine sensitivePlasmodium falciparum strain with IC50 value of 2.720±0.627 μg/ml [103]. Similarly, Bantie et al. [87] evaluated antiplasmodial activities of chloroform, methanol, and aqueous leaf extracts ofC. macrostachyus using a rodent model of malaria. The rodent malaria parasitePlasmodium berghei was used to inoculate healthy male Swiss albino mice, 6–8 weeks old, and the parameters parasitemia, survival time, body weight, temperature, and packed cell volume were then determined using Peter’s and Rane’s tests [87]. Chemoprotective effect exerted by the extracts ranged between 12 and 91% and the chemotherapeutic effect of the extracts was in the range of 39–83%. The crude extracts prevented loss of weight and reduction in temperature but did not affect packed cell volume [87]. In another study, Mohammed et al. [104] evaluated antimalarial activities of the methanol and aqueous leaf extracts ofC. macrostachyus using a 4-day suppressive standard test onPlasmodium berghei. Methanol and aqueous extracts ofC. macrostachyus showed dose-dependent chemosuppressive effect at various doses in mice infected withPlasmodium berghei parasite while the crude methanol extracts ofC. macrostachyus suppressed parasitaemia at all dose levels compared to the negative control groups but did not improve survival time [104]. The mice treated with the methanol and aqueous extracts at 600 mg/kg survived longer (10.60±0.51 days for methanol extract and 9.60±0.51 day for aqueous extract) than those in the negative control group with mean survival time of 6.2±0.20 days [104]. The antimalarial activity test showed thatC. macrostachyus exhibited significant antiplasmodial activity as evidenced by their ability to suppressPlasmodium berghei infection in mice in a dose-dependent manner, which may partly justify the claim by traditional practitioners about the use of these two plants against malaria. Mekonnen [89] also evaluated antiplasmodial activity of 80% methanol extract of the fruit and root ofC. macrostachyus in a rodent model of malaria. The rodent malaria parasitePlasmodium berghei was used to inoculate healthy 8-week-old male Swiss albino mice and the parameters of parasitemia, survival time, body weight, temperature, and packed cell volume were determined using Peter’s test and Rane’s test [89]. Both extracts significantly inhibited parasitemia, increased survival time, prevented loss of weight and temperature, but did not affect the packed cell volume [89]. Results of this study suggest that the root and fruit extracts ofC. macrostachyus have promising antiplasmodial activity againstPlasmodium berghei in a dose-dependent manner, which supports the folkloric use of the plant for treating malaria.


## 6.12. Larvicidal

Karunamoorthi and Ilango [19] evaluated larvicidal activities of methanol leaf extracts ofC. macrostachyus against late third instar larvae ofAnopheles arabiensis Patton, a potent malaria vector. The larval mortality was observed 24 h of posttreatment. The methanol leaf extracts showed different degree of mortality against the malaria vectorAnopheles arabiensis with LC50 and LC90 values of 89.25 and 224.98 ppm, respectively. These results establish thatC. macrostachyus could serve as potent mosquito larvicidal agent againstAnopheles arabiensis although its mode of actions and larvicidal efficiency under the field conditions should be investigated and determined.


## 6.13. Toxicity

The results of toxicity studies of aqueous and hydroalcoholic bark extracts ofC. macrostachyus using albino mice showed LD50 value of 190.2±15.7 mg/kg for aqueous extract and LD50 value of 87.5±12.3 mg/kg for hydroalcoholic extract [73]. Desta [73] determined the median effective single dose ofC. macrostachyus bark extract, that is, the dose that expelledTaenia saginata L. worms partially or totally in 50% of worm-infested human volunteers.Croton macrostachyus showed median effective single dose of 6.42±0.82 and the number of hours that elapsed before partial or total expulsion of the worms following administration ofC. macrostachyus was 12.9±2.1 hours. Gadir et al. [106] evaluated oral toxicity ofC. macrostachyus seeds in Nubian goat kids through clinical, hematological, and pathophysiological parameters. The Nubian goat kids were allotted as untreated controls and groundC. macrostachyus seeds were given to kids in repeated daily oral doses of 1 g/kg or 0.25 g/kg. Both oral dose levels ofC. macrostachyus seeds were lethal for kids between days 7 and 21 and caused bloody diarrhoea, dyspnea, dehydration, loss in condition, paresis of the hind limbs, and recumbency before death [106]. Lesions in the affected animals included widespread hemorrhages and congestion, enterohepatonephrotoxicity, pulmonary hemorrhage, emphysema and cyanosis, tracheal froths, ascites, and hydropericardium. These lesions were accompanied by increases in the activity of serum AST, in the concentration of urea, and decreases in total protein and albumin, anemia, and leukopenia [106]. Moshi et al. [43] evaluated toxicity of root aqueous ethanol extracts ofC. macrostachyus using the brine shrimp lethality test.Croton macrostachyus demonstrated moderate toxicity with concentration killing 50% (LC50) of the shrimps at 13.40 μg/ml. These findings indicate the possibility thatC. macrostachyus extracts may be toxic or contain useful cytotoxic compounds, which were not reported by the traditional healers. Wagate et al. [96] evaluated cytotoxicity of leaf and root methanolic extracts ofC. macrostachyus using the brine shrimp lethality test.Croton macrostachyus showed LC50 value of 387 μg/mL, which was considered to be relatively nontoxic [96].Mbiantcha et al. [107] evaluated toxicity of aqueous and methylene chloride/methanol extracts of C.macrostachyus stem bark usingArtemia spp. lethality assay, mice and Wistar rats. For the cytotoxicity study, the aqueous and organic extracts were administered to larvae ofArtemia spp. and the number of deaths was determined after 6 hours and 24 hours, while for the acute study, the extracts were administered to mice. In the cytotoxicity study, aqueous and organic extracts showed LC50 values of 569 and 425 μg/ml, respectively. In acute toxicity study, aqueous extract did not provoke death until the dose 16 g/kg, whereas the organic extract caused general behaviors, adverse effects, and mortality. Mortality increased with increasing doses, with LD50 values of 10.2 and 9.4 g/kg bwt, respectively, for male and female mice [107]. In another acute toxicity study in mice, the methanol leaf extract ofC. macrostachyus at a single oral doses of 2 and 5 g/kg bwt caused no mortality within the first 24 h and up to 14 days observation period [87]. Results from the study suggested safety profile of this herbal extract in the study mice. Physical and behavioral observations of the experimental mice did not show any visible signs of overt toxicity such as lacrimation, loss of appetite, tremors, hair erection, salivation, and diarrhoea. These studies revealed thatC. macrostachyus is not toxic in both acute and subacute tests at the tested doses of the extracts. In anin vivo study, the methanol extract ofC. macrostachyus showed dose-dependent chemosuppressive effect at various dose levels, that is, 200 (21.1%), 400 (27.7%), and 600 (34.3%) mg/kg body weight inPlasmodium berghei-infected mice [104]. The mice treated with chloroquine were completely free from parasitemia on day 4 in all groups (100% suppression). The crude methanol extract ofC. macrostachyus significantly suppressed parasitemia at all dose levels compared to the negative control groups (distilled water) but did not significantly prolong the survival time of infected mice. Similarly, the aqueous extract at the doses of 200, 400, and 600 mg/kg body weight significantly reduced % parasitemia (26.14, 30.50, and 50.53%, resp.) compared to the negative control group in this study. Mbunde et al. [27] evaluated toxicity of leaf dichloromethane extracts ofC. macrostachyus using the brine shrimp lethality test.Croton macrostachyus demonstrated moderate toxicity with concentration killing 50% (LC50) of the shrimps at 12.94 μg/ml [27]. Omosa et al. [108] also evaluated the cytotoxicity of dichloromethane and methanol (1 : 1) extract ofC. macrostachyus stem bark using the resazurin reduction assay against CCRF-CEM leukemia cell line. The dichloromethane and methanol extract ofC. macrostachyus stem bark displayed cytotoxicity towards leukemia CCRF-CEM cells with IC50 value of 60.6 μg/mL [108]. Based on the cytotoxicity studies done on C. macrostachyus crude extracts [27, 43, 73, 96, 104, 106–108], it can be concluded that caution must be exercised in the use of the species as herbal medicine.


## 7. Conclusion

The present review summarizes the ethnomedicinal uses and recent findings on phytochemistry, pharmacology, and cytotoxicity of different extracts and compounds ofC. macrostachyus. Alkaloids, amino acids, anthraquinones, carbohydrates, cardiac glycosides, coumarins, essential oil, fatty acids, flavonoids, phenolic compounds, phlobatannins, polyphenols, phytosteroides, saponins, sterols, tannins, terpenoids, unsaturated sterol, vitamin C, and withanoides have been demonstrated to be the main active ingredients ofC. macrostachyus. Pharmacological studies have also focused on evaluating anthelmintic, antibacterial, antimycobacterial, antidiarrhoeal, antifungal, anticonvulsant and sedative, antidiabetic, anti-inflammatory, antileishmanial, antioxidant, antiplasmodial, larvicidal, and cytotoxicity activities of the different extracts and compounds isolated fromC. macrostachyus. Future research should focus on the mechanisms of action of bioactive constituents of the species to illustrate the correlation between the ethnomedicinal uses and pharmacological properties of the species. Since previous studies have established thatC. macrostachyus may contain potentially toxic compounds, there is need for detailed toxicological review of the crude extracts and pure compounds of the species. Lastly, sinceC. macrostachyus is widely used in combination with other plant species in various herbal concoctions, there is need for extensive research to evaluate synergistic effects of the different extracts or pure isolates to evaluate their ability to enhance the efficiency of the additive mixtures.



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*Source: 1694671-2017-10-12.xml*