Identification of anti-Caenorhabditis and anti-Onchocerca constituents from leaves of Annona senegalensis Pers. (Annonaceae)

Abstract

Onchocerciasis is a filarial disease caused by Onchocerca volvulus and transmitted through the bite of a blackfly of the genus Simulium. The microfilaricidal drug ivermectin has long been relied on to treat onchocerciasis. Nowadays, the focus is on the complete elimination of the disease through the development of macro-filaricidal drugs. In this study, a hydro-alcoholic extract from Annona senegalensis leaves was screened for micro- and macrofilaricidal activities against the cattle parasitic nematode Onchocerca ochengi and the free-living nematode Caenorhabditis elegans, both model organisms. Worms were assessed by in vitro motility/mortality assay studies and incubated with the various natural products and their effects on mortality were monitored after 48 h. The crude extract showed high activity with LC50 = 1450.2 µg/mL on the young adult of C. elegans wild type and 19.63 µg/mL on adult males of O. ochengi after 48 h post-exposure. The compounds, Quercetin-3-O-glucoside, (+)-Catechin, (-)-Epicatechin, Rutin and AS14.5, displayed LC50 of 179.3, 840.5, 1270.3, 118.2 and 129.7 µg/mL on C. elegans wild type (young adult), respectively, and 7.3, 17.5, 12.6, 6.6 and 11.5 µg/mL on O. ochengi (adult males), respectively, after 48 h. These data support the use of Annona senegalensis for the treatment of infections caused by Onchocerca volvulus.