In vivo Toxicity Study and Antifilarial Activity of Four Plants from Nord-Cameroon

Aims: The objective of this work was to seek an alternative drug against onchocerciasis based on medicinal plants.

Study Design: Ethanolic extracts of stem barks, leaves and roots of Detarium microcarpum, Guiera senegalensis, Trichilia emetica and Vitellaria paradoxa were evaluated in vitro against the cattle filarial parasite Onchocerca ochengi, a model organism similar to Onchocerca volvulus.

Place and Duration of Study: The work took place at the Laboratory of Parasitology of the Institute of Agricultural Research for Development of Ngaoundere between October 2014 and February 2015.

Methodology: Adult worms were incubated in RPMI 1640 medium supplemented with antibiotics, and different concentrations of the extracts of the four plants. Mortality was registered after 24, 48 and 72 h of incubation at 37ºC. Ivermectin and M9-DMSO were the positive and negative controls respectively.

Results: All parts of plants showed anthelmintic activities after 72 h of incubation. The Means of LC50 values were determined graphically and varied from 5 to 60 µg/mL after 72 h incubation. The most antifilarial activities were obtained from stem barks and leaves of D. microcarpum with LC50 of 5 and 7.9 μg/mL on adult worms respectively, while the least antifilarial activity was obtained from stem barks of V. paradoxa with LC50 of 60 µg/mL. These results show that at low concentrations, leaves and stem barks of D. microcarpum are effective in killing O. ochengi worms. Additionally, in vivo toxicity tests using mice showed that the four plants are not toxic.

Conclusion: The findings of the present study support the use of these plants against nematode infections by traditional healers and pastoralists in Cameroon and could represent an alternative anthelminthic for onchocerciasis treatment.