Abstract: From the dried roots and leaves of Tripterygium wilfordii 1.2, a new diterpenoid triepoxide, 16-hydroxytriptolide was isolated, and its structure and stereochemistry elucidated as 16-S-hydroxy-triptolide on the basis of spectral data IR, MS, UV, ¹H NMR, ¹³C NMR, ²D NMR, Selective Long-range DEPT and x-ray crystallographic analysis. This compound showed definite antiinflammatory action, strong immunosuppressive and antifertile activities. In addition, a known compound, triptolide was also isolated and all the spectral signals of ¹H NMR and ¹³C NMR were assigned.

Key words: Tripterygium wilfordii, Diterpenoid lactone, Diterpenoid epoxide, 16-Hydroxytriptolide, Triptolide