Inhibition of 12-O-tetradecanoylphorbol-13-acetate promoted mouse skin papilloma by digalactosyl diacylglycerols from the fresh water cyanobacterium Phormidium tenue.

To search for possible antitumor-promoters, two digalactosyl diacylglycerols (DGDGs), which were obtained from the freshwater cyanobacterium Phormidium tenue and possessed a single pair of acyl residues, were evaluated for their inhibitory effects on the two-stage carcinogenesis test in mouse skin. Papillomas in mouse skin were initiated with 390 nmol of 7,12-O-dimethylbenz[a]anthracene and 1 week later, were promoted twice a week with 1.7 nmol of 12-O-tetradecanoylphorbol-13-acetate (TPA). Two DGDGs effectively inhibited tumor formation in the sensitive mouse stock even when these compounds were given 1 h before TPA treatment.