In vitro anti-HIV and cytotoxic effects of pure compounds isolated from Croton macrostachyus Hochst. Ex Delile

Croton macrostachyus is an important plant in traditional African medicine, widely utilized to treat a variety of diseases. In Kenya, HIV-infected patients use leaf and root decoctions of the plant as a cure for cough, back pain, bleeding, skin diseases, warts, pneumonia, and wounds. This study aimed to evaluate the anti-HIV activities and cytotoxic effects of extracts and chemical constituents isolated from C. macrostachyus. In our previous study we demonstrated that the hexane, CH 2 Cl 2 , ethyl acetate and methanol soluble fractions of a 1:1 v/v/ CH 2 Cl 2 /MeOH crude extracts of the leaves and stem bark of C. macrostachyus exhibited potent anti-HIV activities against HIV-1 with IC 50 values ranging from 0.02–8.1 μg/mL and cytotoxicity effects against MT-4 cells ranging from IC 50 = 0.58–174 μg/mL . Hence, hexane soluble extract of 1:1 v/v/ CH 2 Cl 2 /MeOH crude extract of the leaves of C. macrostachyus, that was more potent against HIV-1 at IC 50 = 0.02 μg/mL was subjected to column chromatography leading to the isolation of 2-methoxy benzyl benzoate (1), lupenone (2), lupeol acetate (3), betulin (4), lupeol (5), sitosterol (6) and stigmasterol (7). Lupenone (2), lupeol acetate (3) and betulin (4) exhibited anti-HIV-1 inhibition at IC 50 = 4.7 nM, 4.3 and 4.5 μg/mL respectively. The results obtained from this study support the potential of C. macrostachyus, as a source of anti-HIV constituents.