Preventive effect of onion extract on the formation and cytotoxicity of glycated amadori-phosphatidylethanolamine

"Attention is recently paid to the involvement of aminophospholipid-linked Maillard compounds (i.e., glycated Amadori-phosphatidylethanolamine; Amadori-PE) in the food denaturalization as well as in the pathogenesis of diabetes and aging. However, to date, there are no available candidates for lipid glycation inhibitor. To obtain information about the compounds that inhibit the lipid glycation, we have now investigated the inhibitory effect on Amadori-PE formation and lipid glycationmediated cell death by the onion extract. When l,2-di(cis-9-octadecenoyl)-sn-glycero-3-phosphoethanolamine (dioleoyl PE) was incubated with D-glucose at 60degC for 1 day in methanol, 50mol% of dioleoyl PE was converted into Amadori-PE. Treatment of cultured macrophage J774A.1 cells with lipid extract prepared from incubation mixture of dioleoyl-PE/glucose produced cell-death. Such Amadori-PE formation and cytotoxity were both effectively suppressed by the addition of small amount of onion extract (0.1%, v/v) to incubation medium of dioleoyl-PE/glucose. This is the first report specifying that onion contains lipid glycation inhibitor, thereby ameliorates lipid glycationmediated cell death by preventing the formation of Amadori-PE."