Cytotoxic diterpenes triptolide, tripdiolide, and cytotoxic triterpenes from tissue cultures of Tripterygium wilfordii

Plant tissue cultures of Tripterygium wilfordii Hook F produced the cytotoxic diterpene triepoxides tripdiolide (1) and triptolide (2) in yields that were 16 and 3 times greater, respectively, than those observed in the plant itself. Other diterpenes, dehydroabietic acid (3) and 15-hydroxy-18-norabieta-3,8,11,13-tetraene-3-oic acid methyl ester (4) were also isolated. Co-occuring in these cultures were the cytotoxic quinone-methides, celastrol (5), compound 6, and compound 7. Other triterpenes produced were oleanolic acid (8) and polpunonic acid (9). β-Sitosterol (17) was also isolated. The proposed structure of 4 was confirmed by synthesis starting from compound 3. Cytotoxic data are reported, and a possible biosynthetic relationship among dehydroabietic acid, compound 4, and tripdiolide (1) is presented.