Anthelmintic activity of medicinal plants used in Côte d'Ivoire for treating parasitic diseases

Phytochemical analysis and anthelmintic activity of Combretum mucronatum leaf extract against infective larvae of soil-transmitted helminths including ruminant gastrointestinal nematodes

BACKGROUND

Soil-transmitted helminths (STH) infect more than a quarter of the world's human population. In the absence of vaccines for most animal and human gastrointestinal nematodes (GIN), treatment of infections primarily relies on anthelmintic drugs, while resistance is a growing threat. Therefore, there is a need to find alternatives to current anthelmintic drugs, especially those with novel modes of action. The present work aimed to study the composition and anthelmintic activity of Combretum mucronatum leaf extract (CMLE) by phytochemical analysis and larval migration inhibition assays, respectively.

METHODS

Combretum mucronatum leaves were defatted with petroleum ether and the residue was extracted by ethanol/water (1/1) followed by freeze-drying. The proanthocyanidins and flavonoids were characterized by thin layer chromatography (TLC) and ultra-high performance liquid chromatography (UPLC). To evaluate the inhibitory activity of this extract, larval migration assays with STH and GIN were performed. For this purpose, infective larvae of the helminths were, if necessary, exsheathed (Ancylostoma caninum, GIN) and incubated with different concentrations of CMLE.

RESULTS

CMLE was found to be rich in flavonoids and proanthocyanidins; catechin and epicatechin were therefore quantified for standardization of the extract. Data indicate that CMLE had a significant effect on larval migration. The effect was dose-dependent and higher concentrations (1000 µg/mL) exerted significantly higher larvicidal effect (P < 0.001) compared with the negative control (1% dimethyl sulfoxide, DMSO) and lower concentrations (≤ 100 µg/ml). Infective larvae of Ascaris suum [half-maximal inhibitory concentration (IC50) = 5.5 µg/mL], Trichuris suis (IC50 = 7.4 µg/mL), and A. caninum (IC50 = 18.9 µg/mL) were more sensitive to CMLE than that of Toxocara canis (IC50 = 310.0 µg/mL), while infective larvae of Toxocara cati were largely unaffected (IC50 > 1000 µg/mL). Likewise, CMLE was active against most infective larvae of soil-transmitted ruminant GIN, except for Cooperia punctata. Trichostrongylus colubriformis was most sensitive to CMLE (IC50 = 2.1 µg/mL) followed by Cooperia oncophora (IC50 = 27.6 µg/mL), Ostertagia ostertagi (IC50 = 48.5 µg/mL), Trichostrongylus axei (IC50 = 54.7 µg/mL), Haemonchus contortus (IC50 = 145.6 µg/mL), and Cooperia curticei (IC50 = 156.6 µg/mL).

CONCLUSIONS

These results indicate that CMLE exhibits promising anthelmintic properties against infective larvae of a large variety of soil-transmitted nematodes.

In Vitro Filaricidal Properties of Aqueous Extracts of Combretum nigricans (Combretaceae) on Onchocerca ochengi (Onchocercidae)

Aim

Onchocerciasis is an endemic parasitic disease in sub-Saharan Africa that significantly impacts animal and human health. In Northern Cameroon, medicinal plants from the Combretum genus are used for onchocerciasis traditional treatment although there is no scientific evidence of their antifilarial potential. This study evaluates the in vitro macro- and microfilaricidal properties of water extracts from Combretum nigricans in Onchocerca ochengi. Material and Methods. O. ochengi microfilariae and adult male worms were recovered from cowhide fragments. Oxidative stress indicators and motility tests were used to assess the filaricidal impact. Female albino rats were used to test for acute toxicity. The contents of secondary metabolites were quantified.

Results

The bark aqueous extract was more active on macrofilariae at 1 mg/mL for 24 h (100%) than the leaf (63.9%) and root (75%) extracts at the same concentration. Likewise, a stronger microfilaricidal effect was found with this extract at 0.5 mg/mL for 1 h (100%) compared to root and leaf extracts. The dose-response effect with the bark extract gave an inhibitory concentration 50 (IC50) of 351 μg/mL vs. 113 μg/mL for flubendazole after 24 h incubation, while the microfilaricidal efficacy revealed an IC50 of 158.7 μg/mL vs. 54.09 μg/mL for ivermectin after one-hour incubation. Examining stress indicators on parasite homogenates showed that macrofilaricidal activity is associated with a significant increase in nitric oxide, glutathione, and malondialdehyde generation and a decrease in catalase activity. At 2000 mg/kg, rats showed no harm. The phytochemical investigation revealed that the barks contained more phenolic acids, condensed tannins, flavonoids, and saponins than the leaves (p < 0.001).

Conclusion

These findings support C. nigricans' antifilarial activity and identify oxidative stress indicators as prospective treatment targets in O. ochengi. It would be interesting to conduct in vivo studies to understand their antifilarial activity better.

Another decade of Trichuris muris research: An update and application of key discoveries

The mouse whipworm, Trichuris muris, has been used for over 60 years as a tractable model for human trichuriasis, caused by the related whipworm species, T. trichiura. The history of T. muris research, from the discovery of the parasite in 1761 to understanding the lifecycle and outcome of infection with different doses (high versus low dose infection), as well as the immune mechanisms associated with parasite expulsion and chronic infection have been detailed in an earlier review published in 2013. Here, we review recent advances in our understanding of whipworm biology, host-parasite interactions and basic immunology brought about using the T. muris mouse model, focussing on developments from the last decade. In addition to the traditional high/low dose infection models that have formed the mainstay of T. muris research to date, novel models involving trickle (repeated low dose) infection in laboratory mice or infection in wild or semi-wild mice have led to important insights into how immunity develops in situ in a multivariate environment, while the use of novel techniques such as the development of caecal organoids (enabling the study of larval development ex vivo) promise to deliver important insights into host-parasite interactions. In addition, the genome and transcriptome analyses of T. muris and T. trichiura have proven to be invaluable tools, particularly in the context of vaccine development and identification of secreted products including proteins, extracellular vesicles and micro-RNAs, shedding further light on how these parasites communicate with their host and modulate the immune response to promote their own survival.

Ethnoveterinary survey of trypanocidal medicinal plants of the beninese pharmacopoeia in the management of bovine trypanosomosis in North Benin (West Africa)

Cattle breeding is of great socio-economic importance for Benin's cattle farmers in general and those of North Benin in particular. The objective of this study is to inventory the natural products of medicinal plants of the Beninese pharmacopoeia for the management of trypanosomes in cattle in North Benin. The methodology consisted of individual and semi-structured interviews with cattle farmers on the use of medicinal plants. A total of 360 cattle farmers were selected and interviewed in twelve villages in four municipalities (Tchaourou, N'dali, Bembèrèkè and Gogounou) in northern Benin. Different quantitative ethnobotanical indices were calculated to determine the level of use of plant species. The Relative Frequency of Citation (RFC), the Informant Consensus Factor (ICF = 0.918) and the Generic Coefficient (Rg = 1.04) were evaluated. The knowledge of medicinal plants was influenced by the level of education and the main activity of those who practiced animal husbandry. The results yielded 48 medicinal plants for veterinary use belonging to 46 genera and 28 families. The Leguminosae family (12.50%) was the most represented. The most cited plants with a RFC above 10% were K. senegalensis, P. africana, K. africana, M. inermis, S. latifolius, M. polyandra. The parts used were leaves (46.15%); barks (24.62%) and roots (15.38%). Decoction (53.23%), plundering (32.26%) and maceration (11.26%) were the main methods of preparation. The administration was mainly by oral route. The calculated indices show a high diversity of medicinal plants with trypanocidal properties in the control of cattle trypanosomosis in the Sudanese and Sudano-Guinean zones of northern Benin. Plant species with high citation and RFC values should be selected for comprehensive pharmacological and phytochemical research to validate this ethnomedical knowledge in the management of cattle trypanosomosis.

In vitro nematocidal potential of hydro-ethanolic and aqueous extracts of Calotropis procera (Aiton) W.T. Aiton, 1811 (Apocynaceae) and Faidherbia albida (Delile) A. Chev., 1934 (Fabacae) against Onchocerca ochengi and Caenorhabditiselegans

Onchocerciasis caused by Onchocerca volvulus Leuckart, 1893 is the second-world infection responsible for human blindness. Except Ivermectin which has as targets the microfilariae of that parasite, specific treatment for this disease does not exist and in developing countries, medicinal plants seem to remedy that health problem. For that, aqueous and hydro-ethanolic leaf, bark, and root extracts of Calotropis procera and Faidherbia albida were evaluated in vitro, against the most popular bovine model, Onchocerca ochengi and the free-resistant nematode Caenorhabditis elegans. O. ochengi microfilariae and adults extracted from the bovine nodules and skins as well as the free strains of C. elegans were exposed to the various concentrations of the plant parts extracts and Ivermectin. In results, all the plant parts extracts were rich in tannins, saponins, alkaloids, flavonoids, phenols, coumarins, and glycosides. Phenols (175.45 ± 0.01 mg EGA/g DM), flavonoids (158.98 ± 0.05 mg EC/g DM), and tannins (89.98 ± 2.56 mg ETA/g DM) contents were high in the bark hydro-ethanolic extract of F. albida. The leaf hydro-ethanolic extract of F. albida induced high activity against O. ochengi microfilariae (CL₅₀ = 0.13 mg/mL). The bark hydro-ethanolic extract of F. albida was also the most effective on O. ochengi adults and particularly on female adults (CL₅₀ = 0.18 mg/mL). Against the parasite strain resistant to Ivermectin, F. albida leaf hydro-ethanolic extract appeared more active with CL₅₀ = 0.13 mg/mL. Similarly, the bark hydro-ethanolic extract of F. albida was the most potent on the wild strain of C. elegans. Thus, this study validates the use of these plants by traditional healers in the management of onchocerciasis and suggests a new source of isolation of the potential plant compounds against Onchocerca.

Ethnobotanical knowledge on native Brazilian medicinal plants traditionally used as anthelmintic agents - A review

Intestinal helminthiasis is a neglected disease that affects a significant portion of the global population, specifically in developing countries, where medicinal plants are widely used for therapeutic purposes. With the purpose to identify the native species used in traditional Brazilian medicine for the management of helminthiasis, ethnopharmacological books edited in Brazil documenting the folk use of medicinal plants were analyzed. The native species cited in at least three studies were selected, and bibliographic research was performed using electronic databases to identify their scientifically validated anthelmintic properties. The search retrieved 133 native species belonging to 88 genera and 43 families from all six Brazilian biomes. Fabaceae (14 Genera and 25 Species) and Asteraceae (7 Genera and 8 Species) were the most frequently cited families. The most reported native species were Baccharis crispa Spreng., Hymenaea courbaril L., Senna occidentalis (L.) Link, Carapa guianensis Aubl., Stachytarpheta cayennensis (Rich.) Vahl, Annona glabra L., Hymenaea stigonocarpa Mart. ex Hayne, Spigelia anthelmia L., Simarouba versicolor A.St.-Hil. and Anacardium occidentale L. Bark (19%) and leaves (17%) were the most commonly used plant parts, and decoction (27%) was the most preferred method of preparation. Evidence of the anthelmintic properties of most species was confirmed using in vitro assays for key human and animal parasites, including Haemonchus contortus, Hymenolepis diminuta, Schistosoma mansoni and Trichostrongylus spp. The species S. alata, S. occidentalis, A. occidentale, and S. anthelmia have been the subject of many biological studies, supporting their use as vermicides. The overall results obtained in this review revealed that Brazil is rich in traditional herbal medicines used to manage helminthiasis; however pharmacological investigations are lacking to confirm their therapeutic properties. Thus, this study could serve as a baseline to validate their use and encourage further clinical investigation of their vermifuge potential.

Development of an Analytical Workflow to Support the Establishment of Monographs in African Pharmacopoeias - Combretum mucronatum Leaves as Example

Herbal medicines are invaluable in African medicine, but quality and safety are not documented in many cases. Besides controlled farming, validated quality control methods are needed to ensure identity, purity, and content. Analytical specifications within modern monographs are needed for consistent batch quality. Combretum mucronatum leaves are widely used in West Africa, but state-of-the-art quality control methods and specifications are non-existent. The aim of the following study was the development of ICH-validated chromatographic protocols for identity, purity, content assay, and analytical specifications for consideration into pharmacopoeial monographs. UPLC-ESI-Q-TOF-MS/MS was used for untargeted phytochemical information on composition. Optimisation of extraction was based on phytochemical profiling. HPTLC was used for differentiation of C. mucronatum from other Combretum species and UPLC for simultaneous determination of 7 marker compounds. C. mucronatum batch analyses (n = 49) investigated the influence of harvest time and geographical origin. Pesticides screening from a 349-compound panel were carried out. 30 compounds, identified by LC-MS, were used for characterization of the plant material. Orietin, isoorientin, vitexin and isovitexin were used as specific marker compounds for qualitative and quantitative HPTLC purposes, while UPLC quantified additionally epicatechin, procyanidins B2 and C1. Influence of harvest time and geographic origin on the content of marker compounds was observed. Differences in the metabolite profiles of C. mucronatum compared to related Combretum species were established for quality control purposes. Contamination with high amoounts of chlorpyrifos, and folpet (sum of folpet and phtalimide, expressed as folpet) were also observed.The study provides analytical protocols, analytical specifications and a drafted monograph for consideration for African pharmacopoeias, and reveals potential challenges in the quality of C. mucronatum.

Anthelmintic Agents from African Medicinal Plants: Review and Prospects

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.

Promising effects of herbal compounds against strongyloidiasis: a systematic review

Strongyloidiasis could be a significant global health issue undervalued in several countries, which is caused by Strongyloides spp. Challenges stemming from the use of anthelmintic chemotherapy, such as the development of resistance, the progressive cost of medicines, environmental toxicity of chemicals, and residuals in beast products have increased interest in promoting alternative means of control for the use of plant-based parasite control methods. A study on herbal extracts may offer a less expensive yet equally effective alternative for the prevention and treatment of helminthic multi-resistance. We systematically searched the Web of Sciences, PubMed/MEDLINE, and Scopus databases to explore original publications related to medicinal plants and Strongyloides in English on September 29, 2021. The keywords of medicinal plant, traditional medicine, plant extract, herbal medicine, herbal extract, natural drug, Strongyloides, strongyloidiasis, Strongyloides infection, and helminth were used in our search. Researchers can make use of this review as a quick reference. In this study, we have summarized recent advancements and published investigations on herbal and naturally derived medicines in treating strongyloidiasis undertaken by several researchers worldwide. These medicinal herbs, as well as the active and significant compounds they contain, such as alkaloids, phenolic derivatives, tannins, and terpenes, have been outlined in recent articles. Various studies on herbal remedies to treat strongyloidiasis have been undertaken to date, but further research is still required on moderately effective and low harmful substances.

Anthelmintic Activity, Cytotoxicity, and Phytochemical Screening of Plants Used to Treat Digestive Parasitosis of Small Ruminants in Benin (West Africa)

Simple Summary

In the present study, we explored the anthelmintic activity, cytotoxicity, and chemical composition of the main plants used by small ruminant breeders in Benin to treat digestive parasitosis. The results obtained are relevant in the sense that they will allow a rational use of the plants studied in the control of digestive parasites but also to initiate the process of identification of new anthelmintic molecules in the context of the development of resistance against the most currently used anthelmintic molecules.

Abstract

Medicinal plants continue to be used alone or in combination with veterinary drugs to treat animal ailments, especially in developing countries where livestock farmers often lack access to modern veterinary services and drugs. In addition, digestive parasitosis remain a major constraint for small ruminant livestock. The objective of this study was to screen the anthelmintic activity of the main plants used in the treatment of the digestive parasitosis of small ruminants in Benin. A total of 40 extracts were prepared using the successive maceration of 10 plants in four solvents of increasing polarity. The phytochemical screening of the plants was performed, and the anthelmintic activity of the extracts was evaluated on L3 larvae of Haemonchus contortus. The cytotoxicity of the 40 extracts was determined on WI38 noncancerous fibroblast cells using the MTT assay, and the total phenol content (TPC), total flavonoid content (TFC), and condensed tannin content (CTC) were quantified in the most effective extracts using colorimetric methods. The results show that the plants contained tannins, flavonoids, and triterpenoids which may, in part, justify their anthelmintic activities. All plants gave active extracts at the highest concentration tested (1200 µg/mL). Methanol (MeOH) extracts were, in general, more effective than the hexane (HEX), dichloromethane (DCM), and aqueous (H₂O) ones in inhibiting larval migration, with the MeOH extracts of Terminalia leiocarpa, Adansonia digitata, and Momordica charantia being the most effective. Nevertheless, the MeOH extract of M. charantia was highly cytotoxic at the concentration of 100 µg/mL. The anthelmintic activity of M. charantia, Vitex doniana, and Caesalpinia bonduc was studied on H. contortus for the first time. These results provide scientific information that can be used for better valorization of the anthelmintic potential of the studied plants and to initiate the process of the identification of new anthelmintic molecules.

Plants used in Côte d'Ivoire (West Africa) against ticks: Evaluation for acaricidal activity against Rhipicephalus (Boophilus) microplus

Rhipicephalus (Boophilus) microplus is a tick that is now a real constraint to cattle breeding in many West African countries such as Côte d'Ivoire. Antitick control is difficult because of the cost, ecotoxicity and resistance. The main objective of this study was to evaluate the acaricidal activity of plants used in Côte d'Ivoire for tick infestation control in cattle. Ethanol extracts from 17 plants were tested in vitro on eggs, larvae and adults of two amitraz resistant strains of R. (B.) microplus, using respectively LTT (Larval Tarsal Test), LPT (Larval Packet Test) and AIT (Adult Immersion Test) methods, at concentrations of 5 mg/mL -1 mg/mL. Out of the 22 extracts tested, four showed acaricidal activity against eggs (4 mg/mL) and three against larvae at 5 mg/mL. These extracts inhibited fertility and resulted in adult females mortality. These results give credence to the traditional use of active plants that may be used for plant-based bioacaricide development and R. (B.) microplus control in cattle as well.

Ethnomedicinal study of medicinal plants used by Mizo tribes in Champhai district of Mizoram, India

BACKGROUND

Medicinal plants have been used countless times for curing diseases mainly in developing countries. They are easily available with little to no side effects when compared to modern medicine. This manuscript encompasses information on ethnomedicinal plants in Champhai district, located in the North East Region (NER) of India. The region lies within Indo-Burma biodiversity hotspot. This study will be the first quantitative report on the ethnomedicinal plants used by the local tribes of this region. Knowledge of medicinal plants is mostly acquired by word of mouth, and the knowledge is dying among the local youths with the prevalence of modern medicine. Hence, there is urgency in deciphering and recording such information.

METHODS

Information was gathered through interviews with 200 informants across 15 villages of the Champhai district. From the data obtained, we evaluate indices such as used report (UR), frequency of citation (FC), informant consensus factor (Fic), cultural values (CVs) and relative importance (RI) for all the plant species. Secondary data were obtained from scientific databases such as Pubmed, Sci Finder and Science Direct. The scientific name of the plants was matched and arranged in consultation with the working list of all plant species ( http://www.theplantlist.org ).

RESULTS

Totally, 93 plant species from 53 families and 85 genera were recorded. The most common families are Euphorbiaceae and Asteraceae with six and five species representatives, respectively. Leaves were the most frequently used part of a plant and were usually used in the form of decoction. Curcuma longa has the most cultural value (27.28 CVs) with the highest used report (136 FC), and the highest RI value was Phyllanthus emblica. The main illness categories as per Frequency of citation were muscle/bone problem (0.962 Fic), gastro-intestinal disease (0.956 Fic) and skin care (0.953 Fic).

CONCLUSION

The people of Mizoram living in the Champhai district have an immense knowledge of ethnomedicinal plants. There were no side effects recorded for consuming ethnomedicinal plants. We observed that there is a scope of scientific validation of 10 plant species for their pharmacological activity and 13 species for the phytochemical characterisation or isolation of the phytochemicals. This might pave the path for developing a scientifically validated botanical or lead to semisyntheic derivatives intended for modern medicine.

Ethnoveterinary knowledge of sheep and goat farmers in Benin (West Africa): effect of socioeconomic and environmental factors

Sheep and goats are two of the main animal species raised in Benin and one of the main sources of income for people living in rural areas. Faced with the inaccessibility of synthetic veterinary products and their low purchasing power, the majority of breeders use ethnoveterinary practices to treat small ruminants diseases. The specific objectives of the current study were (1) to document the traditional knowledge regarding the disorder groups treated and the medicinal plants used in the health and zootechnical management of small ruminants in Benin and (2) to assess the effect of gender, ethnicity, agro-ecological zone and herd size associated with them. To achieve these objectives, an ethnoveterinary survey was conducted in different agro-ecological zones from September 2018 to February 2019. A questionnaire was administered to 506 breeders. The data were analyzed through calculation of the Fidelity Level (FL), Cultural Importance Index (CI) and Informant Consensus Factor (ICF). Ten disorder groups were treated by the people surveyed. These were mainly digestive disorders (D) and reproductive disorders (W), both presenting a ICF value of 0.8. A total of 101 medicinal plants belonging to 42 families and 90 genera were recorded. Spondias mombin, Zanthoxylum zanthoxyloides and Khaya senegalensis were the most important plants with CI values of 0.208, 0.125 and 0.121, respectively. Gender, ethnicity, agro-ecological zone and flocks size were the socioeconomic and environmental factors that significantly influenced the level of ethnoveterinary knowledge. Chemical and biological analysis are needed on less studied plants such as, Striga hermonthica, Crossopteryx febrifuga, Elaeis guineensis and Momordica charantia.

Ethnopharmacological uses, phytochemistry, pharmacology, and toxicology of Olax subscorpioidea Oliv (Olacaceae): a review

Background

The plant Olax subscorpioidea Oliv (Olacaceae) is a shrub that is widely available in Africa. It has been used in traditional medicine to treat various diseases including asthma, pain, inflammation, gastrointestinal and central nervous system (CNS) disorders, cough, diabetes mellitus, cancer, infectious diseases, hepatic diseases, and many other diseases. Several phytochemical and pharmacological investigations were conducted on this plant. However, comprehensive information on this medicinally important plant is not available in the literature. Therefore, in this review, we aimed to provide comprehensive and critical information on all the reported ethnomedicinal uses, phytochemistry, pharmacological activities, and potential toxicity of Olax subscorpioidea to highlight its therapeutic potentials based on traditional usage and identify research gaps as a basis for further investigations to develop novel therapeutic compounds.

Main body

The available information about the plant was retrieved from the online bibliographic databases (PubMed and Google Scholar) and published PhD dissertation using the search terms Olax subscorpioidea, traditional uses, ethnomedicinal uses, phytochemistry, pharmacology, toxicology, and safety. Phytochemical studies have shown that the plant contains several bioactive compounds such as rutin, morin, quercetin, caffeic acid, santalbic acid, n-hexadecanoic acid, squalene, nonacosane, hentriacontane, and many more compounds. Also, pharmacological investigations revealed that Olax subscorpioidea has antidepressant, antiepileptic, anti-Alzheimer’s, cytotoxic, antioxidant, antihyperlipidemic, analgesic, antiinflammatory, antiarthritic, antidiabetic, anticancer, antiulcer, antimicrobial, hepatoprotective, apoptotic, antiprotease, and other CNS effects.

Conclusion

Several pharmacological studies on Olax subscorpioidea have established its ethnopharmacological uses. However, there are limited phytochemical and pharmacological studies to validate other folkloric claims of the plant. Therefore, extensive phytochemical and further pre-clinical efficacy and safety evaluations to fully establish its therapeutic potentials and elucidate its mechanisms of pharmacological actions could be necessary.

Graphical abstract

The Genus Eriosema (Fabaceae): From the Ethnopharmacology to an Evidence-Based Phytotherapeutic Perspective?

The genus Eriosema (Fabaceae) includes approximately 150 species widely distributed across tropical and subtropical regions of the world (Africa, Neotropics, Asia and Australia). Throughout these regions, several species are used since centuries in different traditional medicinal systems, while others are used as food or food supplement. The present review attempts to critically summarize current information concerning the uses, phytochemistry and pharmacology of the Eriosema genus and to evaluate the therapeutic potential. The information published in English and French (up to September 2020) on ethnopharmacology or traditional uses, chemistry, pharmacology and toxicology of Eriosema genus was collected from electronic databases [SciFinder, PubMed, Google, Google Scholar, Scopus, Web of Science, Prelude Medicinal Plants—http://www.ethnopharmacologia.org/recherche-dans-prelude/?plant, The Plant List (http://www.theplantlist.org/), POWO (http://powo.science.kew.org/) and IUCN Red List Categories (https://www.iucnredlist.org/)], conference proceedings, books, M.Sc. and Ph.D. dissertations. The information retrieved on the ethnomedicinal indications of Eriosema genus allowed to list 25 species (∼16.6% of the genus). The majority of uses is recorded from Africa. Phytochemical analyses of 8 species led to the identification and/or isolation of 107 compounds, with flavonoids (69.2%), chromones (7.5%) and benzoic acid derivatives (3.7%) as the main chemical classes. Pharmacological investigations with crude extracts and isolated compounds showed a broad range of activities including aphrodisiac, estrogenic, anti-osteoporosis, hypolipidemic, anti-diabetic, anti-diarrheal, anti-microbial, anti-oxidant, anthelmintic, anti-cancer, and acetylcholinesterase inhibitory activities. Despite the low number of Eriosema species tested, there is convincing evidence in vitro and in vivo studies validating some traditional and ethnobotanical uses. However, the utility of several of the described uses has not yet been confirmed in pharmacological studies. Reviewed data could serve as a reference tool and preliminary information for advanced research on Eriosema species.

Antiparasitic effects of ethanolic extracts of Piper arboreum and Jatropha gossypiifolia leaves on cercariae and adult worms of Schistosoma mansoni

New treatment strategies for schistosomiasis should be evaluated, since resistant strains to the only available drug, Praziquantel, have already been described. Thus, we demonstrated antiparasitic effects of ethanolic extracts of Jatropha gossypiifolia and Piper arboreum on cercariae and adult worms of Schistosoma mansoni. The bioassays were performed at 0–10 000 μg mL−1 concentration for 0–72 h. Adult worms were stained with carmine to assess external and internal damage. The chemical screening was performed using high-performance liquid chromatography. P. arboreum displayed the best cercaricidal effect, with a 100% reduction in viability in just 60 min. The extract of J. gossypiifolia was more effective against adult worms, with 100% viability reduction of male and female worms after 12 and 24 h, respectively. P. arboreum and J. gossypiifolia were equally effective in inhibiting the oviposition of S. mansoni (93% reduction) and causing damage to internal and external structures in adult worms. Flavonoids were identified in both the extracts and phenolic compounds and amides only in P. arboreum. Thus, for the first time, it was proven that ethanolic extracts of P. arboreum and J. gossypiifolia leaves are biologically active against cercariae and adult worms of S. mansoni in vitro.

Review: Southern African medicinal plants used as blood purifiers

ETHNOPHARMALOGICAL RELEVANCE

Blood purification practices, also referred to as blood cleansing or detoxification, is an ancient concept which is widespread amongst African traditional medicine, but for which no modern scientific basis exists. There prevails considerable ambiguity in defining what a blood purifier is.

AIM OF THE STUDY

The purpose of this review is to firstly define what a blood purifier is in the context of African traditional medicine and compare to other cultural and westernized interpretations. Thereafter, this study identifies traditionally used medicinal plants used as blood purifiers in southern Africa and correlates these species to scientific studies, which may support evidence for these "blood purifying plant species".

MATERIALS AND METHODS

Ethnobotanical books and review articles were used to identify medicinal plants used for blood purification. Databases such as Scopus, ScienceDirect, PubMed and Google Scholar were used to source scientific articles. An evaluation was made to try correlate traditional use to scientific value of the plant species.

RESULTS

One hundred and fifty nine plant species have been documented as traditional remedies for blood purification. Most of the plant species have some pharmacological activity, however, very little link to the traditional use for blood purification. There has been some justification of the link between blood purification and the use as an antimicrobial and this has been explored in many of the plant species identified as blood purifiers. Other pharmacological studies specifically pertaining to the blood require further attention.

CONCLUSION

Irrespective of the ambiguity of interpretation, medicinal plants used to "cleanse the blood", play an important holistic role in traditional medicine and this review with recommendations for further study provides some value of exploring this theme in the future.

Anthelmintics in the future: current trends in the discovery and development of new drugs against gastrointestinal nematodes

The control of gastrointestinal nematodes (GINs), the most abundant and serious parasites of livestock, has become difficult because of the limited number of available drugs and fast development of drug resistance. Thus, considerable efforts have been devoted to developing new anthelmintics that are efficient against nematodes, especially resistant species. Here, we summarize the most recent results using various approaches: target-based or high-throughput screening (HTS) of compound libraries; the synthesis of new derivatives or new combinations of current anthelmintics; the repurposing of drugs currently approved for other indications; and lastly, the identification of active plant products. We also evaluate the advantages and disadvantages of each of these approaches.

Antimicrobial secondary metabolites from the stem barks and leaves of Monotes kerstingii Gilg (Dipterocarpaceae)

In the search for bioactive natural products from the African flora, three previously undescribed compounds including one stilbene-coumarin derivative (1), one coumarin-carbinol (2) and one fatty glycoside (3) were isolated from the stem bark and leaves of Monotes kerstingii, together with sixteen known compounds (4-19). The structures of the isolated compounds were elucidated based on their NMR and MS spectroscopic data and by comparison of these data with those previously reported in the literature. Compounds 1-19 were screened for anthelmintic and antimicrobial activity. None of the compounds exhibited significant anthelmintic activity. However, compounds 4, 5, 8 and 14 displayed interesting antibacterial activity against B. subtilis at a concentration of 100 μM with respective inhibition percentages of 99, 79, 71 and 100%, respectively, compared to erythromycin used as positive control. In addition, at the same concentration, compound 6 showed remarkable antifungal activity against Septoria tritici with 93.6% growth inhibition and was found to be more active than the positive controls epoconazole and terbinafine displaying 76.6 and 84.3%, respectively .

Biochemical and ultrastructural changes in Raillietina echinobothrida in vitro exposed to extract of Lysimachia ramosa

Lysimachia ramosa (Primulaceae) is a traditionally used medicinal plant, leaves extract of which is being widely used by the Jaintia tribes of Meghalaya, India for controlling helminthiasis. Preliminary investigation carried out on helminth parasites revealed that the crude extract of the plant causes deformity in the surface topography leading to death of the parasites. Therefore, the present study was conducted to identify the specific fraction of the crude leaf extract of the plant responsible for cestocidal efficacy, through biochemical and ultrastructural studies in Raillietina echinobothrida exposed to crude extract and its different fractions namely hexane, chloroform, ethyl acetate and n-butanol. A dose dependent efficacy, with highest rate of mortality among n-butanol exposed parasites was recorded. The treated parasites exhibited complete erosion of microtriches from the tegument, disintegration of muscle bundles, cellular organelles, plasma membrane, nuclear membrane, nucleolus and vacuolization of mitochondria was also observed. Observations on histochemical distribution of some important tegumental enzymes like adenosine triphosphatase (ATPase), alkaline phosphatase (AlkPase), acid phosphatase (AcPase) and 5'Nucleotidase (5'-Nu) revealed a marked diminished stain intensity in the tegument of R. echinobothrida exposed to the crude extract and n-butanol fraction of the crude extract compared to the control. Highest reduction (77.93%) in the activity of ATPase was observed when the parasites exposed to 6 mg n-butanol fraction/ml of PBS. The results suggest that these enzymes act as target for anthelmintic stress caused by the phytochemicals present in the plant.

HPLC-DAD finger printing, antioxidant, cholinesterase, and α-glucosidase inhibitory potentials of a novel plant Olax nana

BACKGROUND

The medicinal importance of a novel plant Olax nana Wall. ex Benth. (family: Olacaceae) was revealed for the first time via HPLC-DAD finger printing, qualitative phytochemical analysis, antioxidant, cholinesterase, and α-glucosidase inhibitory assays.

METHODS

The crude methanolic extract of O. nana (ON-Cr) was subjected to qualitative phytochemical analysis and HPLC-DAD finger printing. The antioxidant potential of ON-Cr was assessed via 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) and hydrogen peroxide (H2O2) free radical scavenging assays. Furthermore, acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities were performed using Ellman's assay, while α- glucosidase inhibitory assay was carried out using a standard protocol.

RESULTS

The qualitative phytochemical analysis of ON-Cr revealed the presence of secondary metabolites like alkaloids, flavonoids, tannins, sterols, saponins and terpenoids. The HPLC-DAD finger printing revealed the presence of 40 potential compounds in ON-Cr. Considerable anti-radical activities was revealed by ON-Cr in the DPPH, ABTS and H2O2 free radical scavenging assays with IC50 values of 71.46, 72.55 and 92.33 μg/mL, respectively. Furthermore, ON-Cr showed potent AChE and BChE inhibitory potentials as indicated by their IC50 values of 33.2 and 55.36 μg/mL, respectively. In the α-glucosidase inhibition assay, ON-Cr exhibited moderate inhibitory propensity with an IC50 value of 639.89 μg/mL.

CONCLUSIONS

This study investigated Olax nana for the first time for detailed qualitative phytochemical tests, HPLC-DAD finger printing analysis, antioxidant, anticholinesterase and α-glucosidase inhibition assays. The antioxidant and cholinesterase inhibitory results were considerable and can provide scientific basis for further studies on the neuroprotective and anti-Alzheimer's potentials of this plant. ON-Cr may further be subjected to fractionation and polarity guided fractionation to narrow down the search for isolation of bioactive compounds.

Investigating Potential Modes of Actions of Mimusops kummel Fruit Extract and Solvent Fractions for Their Antidiarrheal Activities in Mice

Background

Fruits of Mimusops kummel A. DC. (Sapotaceae) are traditionally used for the treatment of diarrhea. The present study aimed at investigating modes of actions of this fruits for antidiarrheal action to guide future drug development process.

Methods

Fractions of chloroform, n-butanol, and water were obtained from 80% methanol extract, which was prepared by maceration. Antidiarrheal activities and the modes of actions were investigated in mice.

Results

In castor oil induced diarrheal model, the extract delayed onset of diarrhea and reduced number and weight of feces at all tested doses significantly. In this model all fractions significantly delayed onset of diarrhea at all tested doses. Charcoal meal test showed that the extract and all the fractions produced a significant antimotility effect at all tested doses. Enteropooling test showed that the extract as well as n-butanol and aqueous fractions at all tested doses produced a significant decline in volume and weight of intestinal contents, whereas chloroform fraction had substantial effect only at high dose.

Conclusion

This study demonstrated that the extract and solvent fractions produced antidiarrheal activities due to dual inhibitory effect, intestinal motility, and fluid secretion, with the aqueous fraction being the most active among fractions in three models.

Anti-Onchocerca and Anti-Caenorhabditis Activity of a Hydro-Alcoholic Extract from the Fruits of Acacia nilotica and Some Proanthocyanidin Derivatives

Acacia nilotica fruits with high tannin content are used in the northern parts of Cameroon as anti-filarial remedies by traditional healers. In this study, the hydro-alcoholic fruit extract (crude extract (CE)) and, one of the main constituents in its most active fractions, (+)-catechin-3-O-gallate (CG), as well as four related proanthocyanidins, (−)-epicatechin-3-O-gallate (ECG), (+)-gallocatechin (GC), (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-O-gallate (EGCG), were assessed for their potential in vitro anthelmintic properties against the free-living model organism Caenorhabditis elegans and against the cattle filarial parasite Onchocerca ochengi. Worms were incubated in the presence of different concentrations of fruit extract, fractions and pure compounds. The effects on mortality were monitored after 48 h. The plant extract and all of the pure tested compounds were active against O. ochengi (LC₅₀ ranging from 1.2 to 11.5 µg/mL on males) and C. elegans (LC₅₀ ranging from 33.8 to 350 µg/mL on wild type). While high LC₅₀ were required for the effects of the compounds on C. elegans, very low LC₅₀ were required against O. ochengi. Importantly, tests for acute oral toxicity (lowest dose: 10 mg/kg) in Wistar rats demonstrated that crude extract and pure compounds were non-toxic and safe to use. Additionally, the results of cytotoxicity tests with the Caco-2 cell line (CC₅₀ ranging from 47.1 to 93.2 µg/mL) confirmed the absence of significant toxicity of the crude extract and pure compounds. These results are in good accordance with the use of A. nilotica against nematode infections by traditional healers, herdsmen and pastoralists in Cameroon.

Dihydrobenz[e][1,4]oxazepin-2(3H)-ones, a new anthelmintic chemotype immobilising whipworm and reducing infectivity in vivo

Trichuris trichiura is a human parasitic whipworm infecting around 500 million people globally, damaging the physical growth and educational performance of those infected. Current drug treatment options are limited and lack efficacy against the worm, preventing an eradication programme. It is therefore important to develop new treatments for trichuriasis. Using Trichuris muris, an established model for T. trichiura, we screened a library of 480 novel drug-like small molecules for compounds causing paralysis of the ex vivo adult parasite. We identified a class of dihydrobenz[e][1,4]oxazepin-2(3H)-one compounds with anthelmintic activity against T. muris. Further screening of structurally related compounds and resynthesis of the most potent molecules led to the identification of 20 active dihydrobenzoxazepinones, a class of molecule not previously implicated in nematode control. The most active immobilise adult T. muris with EC₅₀ values around 25–50μM, comparable to the existing anthelmintic levamisole. The best compounds from this chemotype show low cytotoxicity against murine gut epithelial cells, demonstrating selectivity for the parasite. Developing a novel oral pharmaceutical treatment for a neglected disease and deploying it via mass drug administration is challenging. Interestingly, the dihydrobenzoxazepinone OX02983 reduces the ability of embryonated T. muris eggs to establish infection in the mouse host in vivo. Complementing the potential development of dihydrobenzoxazepinones as an oral anthelmintic, this supports an alternative strategy of developing a therapeutic that acts in the environment, perhaps via a spray, to interrupt the parasite lifecycle. Together these results show that the dihydrobenzoxazepinones are a new class of anthelmintic, active against both egg and adult stages of Trichuris parasites. They demonstrate encouraging selectivity for the parasite, and importantly show considerable scope for further optimisation to improve potency and pharmacokinetic properties with the aim of developing a clinical agent.

Trichuris trichiura is a human parasitic whipworm infecting around 500 million people globally and having major consequences on the physical growth and educational performance of those infected. Current drug treatment options are limited and lack efficacy against the worm. Critically, they lack the effectiveness that would allow for a practical program for eradication of this parasite. It is therefore important to develop new treatments for trichuriasis. We screened for molecules that could paralyse the adult of a closely related mouse parasite, and identified a class of compounds, the dihydrobenzoxazepinones, not previously implicated as anthelmintics. Importantly, our compounds are active against the parasite but show only low toxicity against mouse cells, demonstrating selectivity for the parasite. Dihydrobenzoxazepinones could be developed as potential pharmaceutical treatments for trichuriasis. Since developing and deploying new drugs for neglected diseases by mass administration is challenging, we also explored whether the compounds could potentially be used to interrupt the Trichuris lifecycle by acting on eggs. Our dihydrobenzoxazepinone compounds reduced the ability of T. muris eggs to establish infection in their mouse host. This supports an environmental spray strategy for the control of Trichuris targeting their eggs in environmental hotspots such as latrines.

Phenolic Metabolites of Dalea ornata Affect Both Survival and Motility of the Human Pathogenic Hookworm Ancylostoma ceylanicum

Hookworms are ubiquitous human parasites, infecting nearly one billion people worldwide, and are the leading cause of anemia and malnutrition in resource-limited countries. Current drug treatments rely on the benzimidazole derivatives albendazole and mebendazole, but there is emerging resistance to these drugs. As part of a larger screening effort, using a hamster-based ex vivo assay, anthelmintic activity toward Ancylostoma ceylanicum was observed in the crude extract of aerial parts of Dalea ornata. These studies have led to the isolation and characterization of phenolic metabolites 1-10. The structures were determined by 1D and 2D NMR spectroscopy, and the absolute configuration of 1 was assigned using electronic circular dichroism data. The new compound, (2S)-8-(3-methylbut-2-en-1-yl)-6,7,4'-trihydroxyflavanone (1), was weakly active at 7.3 μM, with 17% reduction in survival of the hookworms after 5 days. The rotenoids deguelin (9) and tephrosin (10), predictably perhaps, were the most active, with complete worm mortality observed by day 4 (or earlier) at 6.3 and 6.0 μM, respectively. The effects of 1-10 on hookworm motility and on toxicity to hamster splenocytes were also explored as important measures of treatment potential.

Ethnobotanical survey of medicinal plants used as anthelmintic remedies in Gabon

ETHNOPHARMACOLOGICAL RELEVANCE

In this article, we report on an ethnobotanical survey realized at the Peyrie market in Libreville on Gabonese medicinal plants used to treat helminthiasis. While several alerts about cases of resistance to conventional anthelmintic treatments are causing to fear a public and animal health issue, the search for new sources of active compounds becomes an urgent issue. In Gabon like in many developing countries, people regularly turn to traditional medicine in case of physical ailments and/or spiritual healing therapies.

MATERIALS AND METHODS

To determine which medicinal plants are traditionally used by the populations of Libreville to fight against nematodes, medicinal plant traders were interviewed with standardized questionnaires. The surveys were conducted in the main market of Libreville. Ethnobotanical data such as frequency and percentage of families, species, administrations pathways, modes of preparations and parts of plants used were analyzed and summarized.

RESULTS

Thirty-four (34) traders were interviewed belonging to five (5) different ethnic groups. Twenty-four 24 plants used to treat intestinal, cutaneous and ocular helminthiasis were listed. The healers mainly turned towards to ligneous species. The parts of the plant used are mostly leaves and trunk bark. Most of the traditional remedies are prepared directly in water and four (4) principal routes were used for administration namely, oral, rectal, ocular and dermal.

CONCLUSION

This study allowed us to list anthelmintic species which will be subjected to a series of chemical and pharmacological assays.

Pharmacological screening of Monotheca buxifolia (Falc.) A. DC. for antinociceptive, anti-inflammatory and antipyretic activities

Background

Medicinal plants have proven their importance as a valuable source of molecules with therapeutic potential. Monotheca buxifolia (Falc.) A. DC. (family: Sapotaceae) is traditionally used as a hematinic, laxative, digestive, anthelmintic, antipyretic, and in the treatment of gastro-urinary disorders. To provide scientific evidence for its folkloric use, the present study investigated Monotheca buxifolia fruit hydro-ethanolic extract (MBHE) for its prospective antinociceptive, anti-inflammatory and antipyretic activities. MBHE was eluted through column chromatography to isolate the bioactive secondary metabolites which may probably involve in its beneficial properties.

Methods

The phytochemical constituents in MBHE was elucidated using UV, IR, ¹H-NMR, ¹³C NMR, 2D-NMR spectra in combination with EIMS and FAB-MS spectrometric techniques and comparison with literature data of related compounds. The antinociceptive activity of MBHE was evaluated in the acetic acid induced abdominal constriction assay; the anti-inflammatory potential was assessed in the carrageenan induced paw edema, while the antipyretic effect was tested against brewer’s yeast induced pyrexia in BALB/c mice at doses of 50, 100 and 150 mg/kg.

Results

Elution of MBHE along with various characterization techniques led to the isolation of oleanolic acid and isoquercetin. Significant attenuation of chemical induced nociception was observed with MBHE at tested doses of 50 mg/kg (P < 0.01, 68.87 %), 100 mg/kg (P < 0.01, 68.87 %) and 150 mg/kg (P < 0.001, 83.02 %). During a duration of 1–5 h in the carrageenan induced paw edema assay, significant ameliorative effect (P < 0.01, P < 0.001) was demonstrated by MBHE at 50 mg/kg (22.94–20 %), 100 mg/kg (33.23–21.13 %) and 150 mg/kg (38.23–25 %). MBHE also significantly alleviated the brewer’s yeast induced pyrexic response when tested at doses of 50 mg/kg (P < 0.05 in 2nd h), 100 mg/kg (P < 0.05, P < 0.01 and P < 0.001 in 1–5 h) and 150 mg/kg (P < 0.01 and P < 0.001 in 1–5 h).

Conclusion

These findings suggest that Monotheca buxifolia possess pain, inflammation and pyrexia ameliorating properties, probably mediated by the presence of oleanolic acid and isoquercetin contents, though the involvement of other important phytochemicals constituents cannot be ignored.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1257-z) contains supplementary material, which is available to authorized users.

Bioassay-Guided Fractionation of a Leaf Extract from Combretum mucronatum with Anthelmintic Activity: Oligomeric Procyanidins as the Active Principle

Combretum mucronatum Schumach. & Thonn. is a medicinal plant widely used in West African traditional medicine for wound healing and the treatment of helminth infections. The present study aimed at a phytochemical characterization of a hydroalcoholic leaf extract of this plant and the identification of the anthelmintic compounds by bioassay-guided fractionation. An EtOH-H₂O (1:1) extract from defatted leaves was partitioned between EtOAc and H₂O. Further fractionation was performed by fast centrifugal partition chromatography, RP18-MPLC and HPLC. Epicatechin (1), oligomeric proanthocyanidins (OPC) 2 to 10 (mainly procyanidins) and flavonoids 11 to 13 were identified as main components of the extract. The hydroalcoholic extract, fractions and purified compounds were tested in vitro for their anthelmintic activity using the model nematode Caenorhabditis elegans. The bioassay-guided fractionation led to the identification of OPCs as the active compounds with a dose-dependent anthelmintic activity ranging from 1 to 1000 μM. Using OPC-clusters with a defined degree of polymerization (DP) revealed that a DP ≥ 3 is necessary for an anthelmintic activity, whereas a DP > 4 does not lead to a further increased inhibitory effect against the helminths. In summary, the findings rationalize the traditional use of C. mucronatum and provide further insight into the anthelmintic activity of condensed tannins.

An ethnopharmacological survey and in vitro confirmation of the ethnopharmacological use of medicinal plants as anthelmintic remedies in the Ashanti region, in the central part of Ghana

ETHNOPHARMACOLOGICAL RELEVANCE

Infections with helminths are still a big problem in many parts of the world. The majority of the people in West Africa treat such infections with medicinal plants related to the local traditional medicine. The present study aims at identifying medicinal plants traditionally used for worm infections in the Ashanti region, Ghana. In vitro screening of selected extracts from plants on which scientific knowledge is limited was to be performed.

MATERIALS AND METHODS

Validated questionnaires were administered to 50 traditional healers in the Ashanti region, Ghana. Interviews and structured conversations were used to obtain relevant information. Quantitative and qualitative evaluation was performed additionally to structured cross-referencing of the data using SciFinder(®) data base. Selected plant species were used for in vitro testing on anthelmintic activity against the free-living model nematode Caenorhabditis elegans.

RESULTS

35 plant species were recorded for the use in humans and 6 for the use in animals. Plant material most frequently used were the seeds from Carica papaya, mentioned by nearly all healers. The plausibility of most plants used for treatment of infections with helminths was given in most cases by documentation of potential anthelmintic activity in recent scientific literature. 9 species from plants not or scarcely described in literature for this indication were investigated on in vitro activity. A hydroethanolic (1:1) extract of Combretum mucronatum was most active with a survival rate of nematodes of 89% at 0.1mg/mL and 58% at 1mg/mL respectively (levamisole 16%). Extracts of Paullinia pinnata and Phyllanthus urinaria were also assessed to exhibit a minor (85% and 89% respectively at 1mg/mL), but still significant activity.

CONCLUSION

Traditional use of anthelmintic plants from Ghana can be well rationalized by cross-referencing with published literature and phytochemical/pharmacological plausibility.The in vitro investigations of extracts from Combretum mucronatum, Paullinia pinnata and Phyllanthus urinaria exhibited significant effects against nematodes. The anthelmintic activity of these plants should be investigated in detail for pinpointing the respective lead structures responsible for the activity.

In vitro anthelmintic assessment of selected phytochemicals against Hymenolepis diminuta, a zoonotic tapeworm

A large number of medicinal plants are used as herbal remedy for the treatment of helminthic diseases in the developing countries, however, far too little attention has been paid to assess the anthelmintic potentials of chemical compounds that are present in these plants. This study was carried out to assess the in vitro anthelmintic effects of biochanin A, ursolic acid, betulinic acid and beta-sitosterol which are the major phytochemicals of Trifolium repens, Houttuynia cordata and Lasia spinosa, the traditionally used anthelmintic plants of Northeast India. The in vitro anthelmintic testing of these phytochemicals was undertaken against Hymenolepis diminuta, a zoonotic tapeworm, and their efficacy was compared with a reference drug, praziquantel. The results revealed that except beta-sitosterol, which showed a very weak anthelmintic effect, remaining all other tested compounds possess highly significant (p ≤ 0.001) and dose-dependent anthelmintic effects. Upon exposure to 0.25, 0.50 and 1 mg/ml concentrations of biochanin A, ursolic acid and betulinic acid, the test parasite H. diminuta, at first, showed a paralyzed state which later culminated into their mortality after short time periods. Of all the phytochemicals tested, betulinic acid (1 mg/ml) showed the best anthelmintic effect and caused the mortality of test parasites at 3.4 ± 0.66 h. In conclusion, the results of this study demonstrate for the first time that betulinic acid, biochanin A and ursolic acid possess significant in vitro anthelmintic effects against H. diminuta, a zoonotic tapeworm, and, therefore, these compounds may be exploited further for anthelmintic drug development.

A penta-substituted pyridine alkaloid from the rhizome of Jatropha elliptica (Pohl) Muell. Arg. is active against Schistosoma mansoni and Biomphalaria glabrata

Jatropha elliptica is a shrub distributed throughout the north and west of Brazil and reputedly possesses a wide range of therapeutical properties. The roots of this plant possess molluscicidal activity and contain terpenoids, coumarin, lignoid, steroids and alkaloid. In the present study, we assessed the schistosomicidal, miracicidal and cercaricidal activities (against Schistosoma mansoni) and molluscicidal activities (against adults and egg masses of Biomphalaria glabrata) of the alkaloid diethyl 4-phenyl-2,6-dimethyl-3,5-pyridinedicarboxylate, isolated from the ethanol extract of the rhizome of J. elliptica, have been determined. The alkaloid was 100 % lethal to adult schistosomes within 4 days at a concentration of 50 μg/mL. Alterations were observed in the schistosome tegument occasioned by treatment with the alkaloid, such as formation of vesicles and vacuolisation. The extent of tegumental damage of the worm was proportional to the time of incubation and to the concentration of compound. The alkaloid also exhibited a potent cercaricidal activity (LC₁₀₀ = 2 μg/mL); it was totally ineffective against miracicidal forms of the parasite. Moreover, the alkaloid presented strong activity against adult snails (LC₉₀ = 36.43 μg/mL) but was inactive against their egg masses. It is observed then the potential of this compound for the development of new therapies for the treatment of schistosomiasis.

In vitro screening of compounds against laboratory and field isolates of human hookworm reveals quantitative differences in anthelmintic susceptibility

A panel of 80 compounds was screened for anthelmintic activity against a laboratory strain of Ancylostoma ceylanicum and field isolates of hookworm obtained from school children in the Kintampo North District of the Brong Ahafo Region of Ghana. Although the laboratory strain of A. ceylanicum was more susceptible to the compounds tested than the field isolates of hookworm, a twofold increase in compound concentration resulted in comparable egg hatch percent inhibition for select compounds. These data provide evidence that the efficacy of anthelmintic compounds may be species-dependent and that field and laboratory strains of hookworm differ in their sensitivities to the anthelmintics tested. These data also suggest that both compound concentration and hookworm species must be considered when screening to identify novel anthelmintic compounds.