Antiprotozoal activities of compounds isolated from croton lobatus l.
In a preliminary evaluation of ethnobotanically selected Beninese medicinal plants for their in vitro antiplasmodial activity, the methanolic extract of the aerial parts of C. lobatus was found to have significant
activity against P. falciparum, antileishmainal and antiprotoazoal assays carried out on some of the isolated compounds. Phytochemical investigation of this extract resulted in the isolation of five compounds: tiliroside (kaempferol-3-O-β-D-(6-E-p-coumaroyl) glycopyranoside) (1), isovitexin (apigenin-6-C-β-D-glucopyranoside) (2), vitexin (apigenin-8-C- β-D-glucopyranoside) (3), chlorogenic acid (acid-5-O-cafféoylquinic) (4) and 4,5-Odicaffeoylquinic acid (5). Vitexin and tiliroside showed the best in vitro antiplasmodial activity against P.
falciparum, with IC50 values of 4.4 and 7.1 mM, respectively. Vitexin also exhibited strong in vitro leishmanicidal and antitrypanosomal activities against Leishmania donovani amastigotes and Trypanosoma
brucei rhodensiense trypomastigotes, with IC50 values of 0.6 and 0.1 mM, respectively.
Key words: Croton lobatus, tiliroside, vitexin, antiprotozoal activity