Cyclic and branched acyl chain galactoglycerolipids and their effect on anti-tumor-promoting activity

Fifteen new galactoglycerolipid analogues, in which one or two branched, alicyclic or aromatic acyl chains are linked to 2-O-beta-D-galactosylglycerol (6'-position or 1,6' positions), were prepared and tested for their anti-tumor-promoting activity using a short-term in vitro assay for Epstein-Barr virus early antigen (EBV-EA) activation. All compounds were active in inhibiting the EBV activation promoted by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), the branched compounds resulting in the most active glycoglycerolipid analogues of the series. The branched 2-O-[6-O-(3-methylbutanoyl)-beta-D-galactopyranosyl]-sn-glycerol (1a) and the structurally related alicyclic 2-O-[6-O-(2-cyclohexylethanoyl)-beta-D-galactopyranosyl]-sn-glycerol (1d), when tested in an in vivo two-stage carcinogenesis test, exhibited inhibitory effects on mouse skin tumor promotion.