Cancer chemopreventive activity of an iridoid glycoside, 8-acetylharpagide, from Ajuga decumbens

In the course of our continuing search for novel cancer chemopreventive age nts from natural sources, several kinds of Labiatae plants were screened. C onsequently, the iridoid glycoside derivative, 8-acetylharpagide (8-AcHarp) , was obtained from the flowering whole plant of Ajuda decumbens as an acti ve constituent. This glycoside exhibited the remarkable inhibitory effect o n two-stage carcinogenesis test of mo use skin tumors induced by nitric oxi de (NO) donor, (+/-)-(E)-methyl-2-[(E)hydroxyimino]-5-nitro-6-methoxy-3-hex eneamide (NOR 1) as an initiator and 12-O-tetradecanoylphorbol-13-acetate ( TPA) as a promoter. Further, 8-AcHarp exhibited potent anti-tumor-promoting activity on two-stage carcinogenesis test of mouse hepatic tumor using N-n itrosodiethylamine (DEN) as an initiator and phenobarbital (PB) as a promot er. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.