Study of the Anthelmintic Properties of Some Extracts of Vernonia Amygdalina and Ageratum Conyzoides (Asteraceae) on the Parasite Onchocerca Ochengi

Abstract

Like most countries in sub-Saharan Africa, Cameroon is affected by onchocerciasis. Commonly referred to as 'river blindness', it is a filariasis caused in humans by the parasite Onchocerca volvulus, which is transmitted to its host by a small fly belonging to the genus Simulium, with only the females being blood-feeding and transmitting the infectious larvae during their blood meals. Chronic infection causes itching and disfiguring lesions on the skin, as well as eye lesions that can lead to irreversible blindness. The current intervention strategy relies on mass drug administration (MDA), specifically ivermectin. Despite the efforts made to combat onchocerciasis, it remains a major public health issue and thus constitutes an obstacle to the socio-economic development of affected communities. Indeed, the absence of a macrofilaricide treatment, the inaccessibility of ivermectin for certain community groups, the prohibition of ivermectin for individuals co-infected with the filaria Loa loa, and the emergence of parasite strains resistant to the only available treatment slow down onchocerciasis elimination projects especially in Africa. Another alternative would then be to exploit the pharmacological properties of certain local medicinal plants that have proven effective in traditional medicine, in the treatment of parasitic diseases, particularly filariasis. The general objective of this work was to formulate anthelmintic molecules from local medicinal plants to effectively fight against onchocerciasis. The methanolic, ethanolic, acetonic, and ethyl acetate extracts of Vernonia amygdalina and Ageratum conyzoides were tested in vitro on the bovine parasite Onchocerca ochengi. Two ranges of concentrations were used: 0 to 300 µg/mL, then from 300 to 600 µg/mL in RPMI-1640. The results obtained from the tests showed that the methanolic and ethanolic extracts of V. amygdalina roots were the most effective with respective LC50 of 68.52±9.33 and 74.66±3.72 µg/mL. Ivermectin used as a positive control revealed the best anthelmintic activity with a LC50 of 17.782±2.018 µg/mL.