Antimalarial activity of alkaloids isolated from Stephania rotunda

Stephania rotunda (Menispermaceae) is used in traditional medicine for the treatment of fever. Four major alkaloids: dehydroroemerine, tetrahydropaimatine, xylopinine, cepharanthine as well as aqueous extract (SA), dichloromethane extracts (SDI and SD2) from this plant were tested against Plasmodium falciparum W2 in vitro. Dehydroroemerine, cepharanthine and SDI were the most active against W2 with IC50 Of 0.36, 0.61 mu M and 0.7 mu g/mL, respectively. Their IC50 on human monocytic THP1 cells were 10.8, 10.3 [LM and >250 mu g/mL, respectively. Cepharanthine, SDI and SA were selected for in vivo antimalarial test against Plasmodium berghei in mice. The results of SDI and SA at dose of 150 mg/kg showed a decrease of 89 and 74% of parasitaemia by intra-peritoneal injection and 62.5 and 46.5% of parasitaemia by oral administration, respectively. The result of cepharanthine at dose of 10 mg/kg showed a decrease of 47% of parasitaemia by intra-peritoneal injection and 50% of parasitaemia by oral administration. Drug interaction of chloroquine and major alkaloids indicates that cepharanthine-chloroquine and tetrahydropaimatine-xylopinine associations are synergistic. These results are in agreement with the use of this plant in the treatment of malaria. This is the first report on in vivo antimalarial investigation for Stephania rotunda. (C) 2007 Elsevier Ireland Ltd. All rights reserved.