Immunostimulatory Phosphatidylmonogalactosyldiacylglycerols (PGDG) from the Marine Diatom : Inspiration for a Novel Synthetic Toll-Like Receptor 4 Agonist.

An unprecedented phosphatidylmonogalactosyldiacylglycerol pool (PGDG, ) rich in polyunsaturated fatty acids was isolated from the marine diatoms . Here we report for the first time the NMR characterization of this rare lipid from marine organisms along with a synthetic strategy for the preparation of a PGDG analog (). PGDG exhibited immunostimulatory activity in human dendritic cells (DCs) and the synthetic PGDG was prepared to explore its mechanism of action. A Toll-like receptor-4 (TLR-4) agonistic activity was evidenced in human and murine DCs underlying the antigen-specific T-cell activation of this class of molecules.