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 diacylgly cerols (DGDGs), which were obtained from the freshwater cyanobacterium Phormidium tenue and possessed a single pair of acyl residues, were e valuated for their inhibitory effects on the two-stage carcinogenesis test in mouse skin. Papillomas in mouse skin were initiated with 390 n mol of 7,12-O-dimethylbenz[a]anthracene and 1 week later, were promote d 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 treat ment.