Anti-AIDS agents, 21. Triterpenoid saponins as anti-HIV principles from fruits of Gleditsia japonica and Gymnocladus chinensis, and a structure-activity correlation.

Gleditsia saponin C [1] and gymnocladus saponin G [2] were isolated from Gleditsia japonica and Gymnocladus chinensis, respectively, as anti-HIV principles. Compounds 1 and 2 demonstrated inhibitory effects against HIV replication in H-9 cells with EC50 values of 1.1 and 2.7 microM, respectively. Evaluation of the anti-HIV activities of the prosapogenins of 1 and 2 suggested that the unusual monoterpenyl moieties in 1 and 2 are essential for their anti-HIV activity. Derivatives of echinocystic acid [8], the aglycone of compound 1, were also prepared and evaluated for inhibitory activity against HIV replication. 3,16-Di-O-acetylechinocystic acid [12] was shown to be an anti-HIV agent with an EC50 value of 2.3 microM.