Immunosuppressive diterpenoids from Tripterygium wilfordii.

A clinically used extract of Tripterygium wilfordii afforded three new diterpenoids-3beta,19-dihydroxyabieta-8,11,13-triene (triptobenzene L) (1); 12,19-dihydroxy-3-oxoabieta-8,11,13-triene (triptobenzene M) (2); and 19-hydroxy-3,7-dioxo-abieta-8,11, 13-triene (triptobenzene N) (3)-along with 14 known diterpenoids. The structures of 1-3 were established on the basis of spectroscopic studies. Of the known compounds, the stereochemistry at C-4 of triptonediol (4) was reassigned. Tripterifordin (8) and 13-epi-manoyl oxide-18-oic acid (9) showed significant inhibitory effects on cytokine production.