Anti-onchocercal properties of three medicinal plants against Onchocerca ochengi

Objective: To evaluate the filaricidal properties of three indigenous medicinal plants— Cassia alata, Zornia scabra , and Momordica (M.) foetida , in order to explore their potential as novel sources of filaricides for the sustainable management of filariasis. Methods: Nine crude extracts from these three plants were prepared and screened in vitro against the microfilariae and adult worms of Onchocerca (O.) ochengi . Viability of O. ochengi adult male worm and mf was ascertained by microscopy while that of adult female worm of O. ochengi was by MTT/formazan assay. Cytotoxicity and acute toxicity were assessed in LLC-MK2 cells and in balb/c mice, respectively. Results: At the single highest concentration of 500 µg/mL, all the extracts were active on O. ochengi adult males while seven showed activity on adult females and microfilariae. The methylene chloride extract of M. foetida was the most active on O. ochengi with IC 50s of 30.3 µg/mL, 40.3 µg/mL, and 44.2 µg/mL on males, females, and microfilariae, respectively. Selectivity indexes for the most active extract were 3.5 µg/mL (microfilariae), 3.9 µg/mL (females), and 5.1 µg/mL (males). There was no physical sign of acute toxicity and no hepatocellular injury to balb/c mice. Conclusions: Extracts of Cassia alata, Zheneria scabra and M. foetida contain nematocidal properties with the methylene chloride extract of M. foetida being the most active on the adult worms and juvenile stages of O. ochengi . These findings provide a base for the isolation of anti-filarial lead molecules from the extract.