Constituents of Tinospora sinensis and their antileishmanial activity against Leishmania donovani.

Two new compounds 4-methyl-heptadec-6-enoic acid ethyl ester (2) and 3-hydroxy-2,9,11-trimethoxy-5,6-dihydro isoquino[3,2-a]isoquinolinylium (7) were isolated from an ethanolic extract of the stems of Tinospora sinensis, along with six known compounds (1, 3-6 and 8). The structures of new compounds were established on the basis of detailed spectroscopic studies. Compound 7 exhibited the highest in vitro antileishmanial activity against Leishmania donovani promastigotes and intracellular amastigotes, whereas compounds 2, 4, 5 and 6 demonstrated moderate activity. Other compounds were found to be inactive.