Bioactive triterpenoids from Kadsura heteroclita.

A phytochemical study of Kadsura heteroclita led to the isolation of eight triterpenoids, including two new compounds, named kadheterilactone A (1) and kadheterilactone B (2), as well as six known compounds, longipedlactone H (3), longipedlactone A (4), longipedlactone F (5), kadsuranic acid A (6), nigranoic acid (7), and schisandronic acid (8). Their structures were elucidated on the basis of spectroscopic methods, including 2D NMR techniques. The cytotoxic activities of 1-8 were tested against several tumor cell lines by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium hydrobromide (MTT) assay in vitro. As a result, 4 and 5 turned out to be significantly cytotoxic against Hep-G2 and Bel-7402 tumor cell lines. All compounds were also tested for inhibition on HIV-1 protease (PR) and reverse transcriptase (RT). Compounds 6 and 7 showed strong inhibition on HIV-1 PR, while 8 exhibited moderate activity, others were only weakly active. No compounds were active against HIV-1 RT.