Synthesis of galactoglycerolipids found in the HT29 human colon carcinoma cell line

Synthesis of three galactoglycerolipids (3-O-(β-d-galactopyranosyl)-1-O-hexadecyl-2-O-palmitoyl-sn-glycerol, 3-O-(α-d-galactopyranosyl-(1→4)-β-d-galactopyranosyl)-1-O-hexadecyl-2-O-palmitoyl-sn-glycerol, 3-O-(α-d-galactopyranosyl-(1→4)-β-d-galactopyranosyl)-1-O-hexadecyl-sn-glycerol), and the corresponding glycerolipid (1-O-hexadecyl-2-O-palmitoyl-sn-glycerol) is described. The first two compounds were recently identified in the human colon carcinoma cell line HT29. The three-carbon synthon (S)-glycidol was used for construction of the glycerol moiety. Glycosylation of (S)-glycidol with protected galactosyl and digalactosyl donors produced galactosyl and digalactosyl glycidols. Lewis acid catalyzed opening of the epoxide produced protected galactosyl and digalactosyl glycerolipids. Deprotection, or palmitoylation followed by deprotection, yielded the target compounds. The corresponding glycerolipid was synthesized analogously and an oxidation–reduction procedure for tritiation was developed. The synthesized compounds will be used in studies of the role of galactosyl glycerolipids in differentiation and colon cancer development.