Inhibitory Effect of Karounidiol on 12-O-Tetradecanoylphorbol-13-acetate-Induced Tumor Promotion.

Karounidiol [D:C-Friedo-oleana-7,9(11)-diene-3 alpha,29-diol] and 7-oxodihydrokarounidiol [7-oxo-D:C-friedo-olean-8-ene-3 alpha,29-diol], isolated from the seeds of Trichosanthes kirilowii, were examined for the effect on 12-O-tetradecanoylphorbol-13-acetate (TPA, 1 microgram/ear)-induced inflammation, following application of this tumor-promoting agent, to the ears of mice. Both compounds inhibited the inflammatory activity induced by TPA and the 50% inhibitory dose for TPA-induced inflammation was 0.3 and 0.4 mg/ear, respectively. Furthermore, at 2 mumol/mouse, karounidiol markedly suppressed the promoting effect of TPA (1 microgram/mouse) on skin tumor formation in mice following initiation with 7,12-dimethylbenz[a]anthracene (50 micrograms/mouse).