Inhibition of P-falciparum by steroids isolated from Solanum nudum

Resistance to antimalarials has been widely reported and constitutes a major problem around the world. In Colombia, resistance of P. falciparum to chloroquine has been reported as 47%-97%, to amodiaquine 3%-7% and to sulfadoxine-pyrimethamine as 9%-13%. The search for new antimalarials is a priority and with this aim we studied the in vitro antimalarial activity of plants used by traditional healers. Incorporation of H-3-hypoxanthine by the strain FCB-2 of P. falciparum was used to measure the degree of inhibition produced by the steroids SN-1 tumacone A (C29H44O5), SN-2 tumacone B (C27H42O4), SN-3 tumacoside A (C35H54O10), and SN-4 tumacoside B (C33H52O9). All compounds were obtained from the dried stems and leaves of Solanum nudum. The mean growth inhibition of P. falciparum was 71%, 56%, 21% and 12% with each of the compounds SN-1, SN-2, SN-3 and SN-4. These results constitute an important discovery since they may account for the antimalarial properties of extracts of Solanum nudum by a sensitive method. Future work should include study of the in vivo antimalarial effect of these extracts. Copyright (C) 2002 John Wiley Sons, Ltd.