Inhibition of the Tumor-Promoting Action of 12-O-Tetradecanoylphorbol-13-Acetate by some Oleanane-Type Triterpenoid Compounds

Abstract

Since glycyrrhetinic acid was proved to suppress tumor promoter effects, several oleanane-type triterpenes which were chemically derived from oleanolic acid and hederagenin were tested in vitro and in vivo against the action of tumor promoter, 12-0-tetradecanoylphorbol 13-acetate. By in vitro experiment monitoring with 12-0-tetradecanoylphorbol-13-acetate-induced stimulation of 32Pi incorporation into phospholipids and an in vivo test on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene and promoted with 12-0-tetradecanoylphorhol-13-acetate, 18β-olean-l 2-ene-3β,28-diol (=erythrodiol), 18β-olean-12-ene-3β,23,28-triol, 18α-olean-l 2-ene-3β,28-diol, and 18α-olean-12-ene-3β,23,28-triol showed remarkable suppressive effects. Especially 18α-oleanane derivatives having a CH2OH grouping converted from the COOH group initially allocated at C-17 were 100 times more effective than glycyrrhetinic acid both in vitro and in vivo. © 1988, American Association for Cancer Research. All rights reserved.