Chemoenzymatic Synthesis of Phospholipid Hydroperoxides

Chemoenzymatic synthesis of 1-stearoyl-2-hydropeoxyacyl-sn-glycerophospholipids including phosphatidylcholine (PC-OOH), phosphatidic acid (PA-OOH), phosphatidylethanolamine (PE-OOH), phosphatidylglycerol (PG-OOH) and phosphatidylserine (PS-OOH). The hydroperoxy acyl moieties were prepared via hydroperoxidation of linoleic, dihomo-γ-linolenic and arachidonic acids by soybean, potate lipoxygenase or autoxidation. Their hydroperoxy group was protected as a dimethylperacetal before condensation with lysophosphatidylcholine. Optically active lysophosphatidylcholine was prepared via short pathway involving lipase-catalyzed direct enantioselective stearoylation of 2-O-benzylglycerol and choline phosphate synthesis. Peroxy fatty acids and lysophosphatidylcholine thus obtained were condensed using dicyclohexylcarbodiimide in chloroform. Removing the peracetal group in the product and purification by reverse-phase chromatography afforded the desired PC-OOH’s. PA-OOH, PG-OOH, PE-OOH and PS-OOH were obtained by phospholipase-D catalyzed transphosphatidylation from PC-OOH. As a reference compound for biological studies of hydroperoxy phopholipid, PC-OH's were also prepared in which hydroxy unsaturated fatty acyl group was linked to the sn-2 position of the glycerophospholipids.