Study On The Formation And Inhibition Of Glycated Phosphatidylethanolamine In DPPE-Glu Model System

Recently,the findings,analytical methods,formation mechanism and inhibition pathways of glycated lipids in foodstuffs have been paid more and more attention since their harmful effect on human health has been reported.Numerous studies have showed the formation and accumulation of glycated lipids in vivo are related to the pathogenesis of many diseases such as diabetes,vascular disease and cataract.Food-derived glycated lipids might make a great contribution to the total body glycated lipids,which indicated that control the intake of food-derived glycated lipids is really necessary.In present research,formation mechanism,impact factors and effective inhibition of glycated phosphatidylethanolamine(glycated PE)during thermal processing in model system were investigated.The mechanisms of the inhibition of catechins and glycated PE were studied,so as to contribute to the inhibition analysis of food-derived glycated lipids.The main results are shown as follow:The formation of food-derived glycated PE in thermal process were investigated by designing 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine(DPPE)-glucose model system heated from 40 to 100 °C for 8 h.The main products of glycated PE were determined by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).Results showed that the glycation of DPPE produced three major glycated compounds: amadori-glycated-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine(Amadori-DPPE),carboxymethyl-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine(CM-DPPE),and carboxyethyl-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine(CE-DPPE).The content of Amadori-DPPE increased with the increase of temperature and extension of time when temperature was lower than 60 °C.However,when the processing temperature was higher than 60 °C,the content of Amadori-DPPE first rapidly increased to reach the maximum and then decreased with the extension of heating time.CM-DPPE and CE-DPPE formation occurred consistently during 8 h of incubation in model system.Higher temperature and extended incubation time promoted the formation of CM-DPPE and CE-DPPE.1-13C-D-glucose-DPPE glycation system was then designed to invest the formation pathways of the three glacated DPPE.Amadori-DPPE was identified to generate CM-DPPE through oxidative cleavage of glycated polar head group under high temperature and extended incubation time.Additionally,during thermal processing,retro-aldol reactions of glucose lead to the formation of two reactive dicarbonyl intermediates: glyoxal(GO)and methylglyoxal(MGO),which in turn reacts with amino group of DPPE to form CM-DPPE and CE-DPPE,respectively.Thus,the formation pathways of CM-PE might involve the irreversible rearrangements of Amadori-PE following oxidative cleavage,as well as the glycation of amino group of PE with GO.CE-PE could only be formed by reaction of PE with MGO.Moreover,the content of CM-DPPE was higher than that of CE-DPPE in the same incubation conditions,which indicated that CM-PE might be a more useful predictive marker for food-derived glycated amino-phospholipid,rather than Amadori-PE,particularly in thermal processed foodstuffs.The effect of lipid oxidation on the formation of glycated PE and the mechanism involved in glycated PE formation were studied in model system of vegetable oil-DPPE-glucose.Result showed that hydroxyl radicals(OH?)generated by oil oxidation could promote the oxidative cleavage of the glycated polar head group of Amadori-DPPE to CM-DPPE.Oil oxidation also generated GO and MGO,which could react with DPPE to form CM-DPPE and CE-DPPE,respectively.With the increase of unsaturated degree,the effect on glycated PE formation in the reaction system is more obvious.The inhibition of four kinds of catechins(EC,ECG,EGC and EGCG),resveratrol,butylated hydroxyanisole(BHA)and tert-Butylhydroquinone(TBHQ)to glycated DPPE formation were investigated by designing inhibitor-DPPE-Glu model system.Results showed that the inhibition rate of catechins to CM-DPPE and CE-DPPE formation was significantly higher than other inhibitors.A variety of catechin-GO and catechin-MGO adducts were detected in the reaction system,as well as EC quinone-DPPE adduct and ECG quinone-DPPE adduct.The results showed that the polyphenols of catechin can oxidized to quinone,and the carbonyl groups of quinone competed with the carbonyl groups of glucose to react with the amino group of DPPE to inhibit the formation of Amadori-DPPE.At the same time,catechins inhibited the oxidative degradation of glucose as well as the formation of GO and MGO by eliminating OH?,and trapped the produced GO and MGO so as to inhibited the generation of CM-DPPE and CE-DPPE.This study investigated the formation rules of glycated PE during thermal processing and identified the major glycated PEs.The formation pathways of glycated PEs were proposed,the effects of lipid oxidation and catechins inhibition on Glycated PEs formation were studied.The research results will theoretically improve the cognitive level of food-derived glycated PEs formation and enhance the development of the research techniques of food-derived glycated PEs inhibition.