Constituents from the stems of Aristolochia manshuriensis.

In a continuing search for bioactive compounds from Aristolochia species, 28 compounds, including three new constituents, demethylaristofolin E (1), aristomanoside (2), and dehydrooxoperezinone (3), were isolated from an extract of the stems of Aristolochia manshuriensis. The structures of these compounds were established by extensive 1D and 2D NMR spectral studies. Among these compounds, dehydrooxoperezinone (3) was found to inhibit the replication of HIV, with an EC(50) value of 17.5 microg/mL and a therapeutic index of 1.43.