Two new anti-tumor promoting serratane-type triterpenoids from the stem bark of Picea jezoensis var. jezoensis

Two new serratane-type triterpenoids, 1 and 2, were isolated from the stem bark of Picea jezoensis Carr. var. jezoensis (Pinaceae). Their structures were determined to be 3beta-methoxyserrat-13-en-21beta-ol (1) and 13beta, 14beta-epoxy-3beta-methoxyserratan-21beta-ol (2) on the basis of spectroscopic methods and partial syntheses. Compounds 1 and 2 and their acetates were screened as potential anti-tumor promoters by using the in vitro short-term 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced Epstein-Barr virus early antigen (EBV-EA) activation assay. IC50 value evaluation showed that compound 1 was more effective than others. In addition, compounds 1 and 2 were examined for antitumor promoting activities in a two-stage carcinogenesis assay of mouse skin tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. Compounds 1 and 2 exhibited significant anti-tumor promoting effects on mouse skin carcinogenesis.