Medicinal plants have been of great importance to many traditional communities for many generations. However, there is need to carry out scientific studies in order to confirm the medicinal properties of many plants used traditionally. Cosmos sulphureus (Asteraceae) used by local communities for the treatment of various diseases has showed antioxidant, antibacterial, antifungal and antiplasmodial properties although there are no studies demonstrating its antionchocerca activity. The present study was undertaken to investigate the antionchocerca potential of crude extracts and chromatographic fractions of C. sulphureus using Onchocerca ochengi, a bovine filarial closest in phylogeny to Onchocerca volvulus. Solvent extraction of the parts of C. sulphureus was performed using distilled water, 70% EtOH, MeOH, CH 2 Cl 2 and a mixture of MeOH/CH 2 Cl 2 (v/v). Anthelmintic assay was evaluated on adult worms of O. ochengi and worm viability was assessed biochemically using the dimethylthiazol (MTT) formazan assay. Acute and sub-acute oral toxicities of the promising extract was investigated in mice. The chemical composition of extracts was revealed. EtOH extract of roots showed highest anthelmintic activity with an LC 50 value of 31.01±1.17 µg/mL which was more significant than the one of ivermectin (LC 50 =42.78 µg/mL) used as standard. The other extracts show moderate activities. The most active fraction obtained from EtOH extract of roots had an LC 50 value of 19.10 µg/mL on male worm. For acute toxicity, a single dose of 2000 mg/kg used induced no critical behavioral changes or death. In sub-acute toxicity, daily oral administration of hydro-ethanolic extracts of roots at the dose of 250, 500 and 750 mg/kg revealed disturbances in the normal growth of animals as well as liver and kidney alterations. These results unfold potential sources of novel anti-onchocerca lead compounds and validate the traditional use of the plants in onchocerciasis treatment.

In Cameroon, the practice of traditional medicine in the treatment of intestinal helminthiasis is a reality and habits in the lives of traditional healers and breeders for various reasons related to their local life situations. In the valorization of medicinal plants in the treatment of digestive parasitosis as an alternative to synthetic anthelmintics, a study was carried out in order to verify their anthelmintic activity and the level of their toxicity. The present study was carried out to determine the in vitro anthelminthic activity of Tephrosia pedicellata extracts. Aqueous and hydroethanolic leaves extracts at different concentrations were tested against Haemonchus contortus development stages, mutant and wild type of free-living nematode Caenorhabditis elegans. The two plant extracts were then chemically screened and their toxicological profile was established using albino rats. Hydroethanolic extract was the most potent by killing Haemonchus contortus adults (LC 50 : 0.038 mg/mL after 24 hours), infesting larvae (LC 50 : 0.22 mg/mL after 48 hours) and inhibiting egg hatching (IC 50 : 0.76 mg/mL after 48 hours). The two plant extracts showed same activity on Caenorhabditis elegans levamisole non-sensitive (LC 50 : 0.26 mg/mL after 48 hours) and sensitive strains (LC 50 : 0.25 mg/mL after 48 hours), showing different mode of action to that of levamisole. Several plant chemicals were identified from both extracts, with higher content of polyphenol compounds (562.91 mg GAE/g DW), flavonoids (135.96 mg RE/g DW), condensed tannins (228.50 mg CE/g DW) and saponins (206.83 mg SE/g DW) obtained with the hydroethanolic extract. No toxic effect was observed during acute toxicity study. Moreover, apart from the significant increase of platelets and Aspartate transaminase (p=0.001) and the glomerular inflammation in the lungs at the dose of 1000 mg/kg, no harmful variation of haematological and biochemical parameters of rats were observed. The pattern of anthelmintic activity of these extracts on Caenorhabditis elegans and the non-toxic effect of hydroethanolic extract provide a way for new anthelminthic drug.