3-Deoxyosone-related advanced glycation end products in foods and biological systems

Abstract

In an intermediate Maillard reaction of proteins with glucose, 3-deoxyglucosone (3DG) was generated from Amadori compounds in an early stage, leading to generation of advanced glycation end products (AGEs). 3DG modified arginine residues to form imidazolone compounds, and lysine residues to form pyrrole aldehydes (lysyl-pyrraline) and lysyl-pyrropyridine. S16 and S17, imidazolone compounds, are formed via S12, imidazoline-4-one compound, by dehydration and oxidation from the Nα-benzoylarginine amide (BzArgNH2)–3DG reaction system to be the major pathway. A novel spiro compound, S17, was formed by intramolecular cyclization of dehydrogenated S12. S12 was also identified in a 3DG–insulin or angiotensin II reaction system under physiologic conditions at 37 °C. These 3DG-related AGEs, imidazolone, pyrraline, lysyl-pyrropiridine, and pentosidine were detected in browned foods, such as soy sauce, as well as in vivo. 3DG, which has weaker mutagenicity, reacted readily with 2′-deoxyguanosine in DNA. Two major products (G–A and G–B) were isolated, and identified as diastereomers of N-(1-oxo-2,4,5,6-hydroxyhexyl)-2′-deoxyguanosine. Blue pigment was isolated from the reaction between d-xylose and glycine. Blue pigment which was designated Blue-M1 (blue Maillard reaction intermediate-1) was identified as novel pyrrolopyrrolylium compound and is assumed to be a dimer of yellow pyrrolopyrrole-2-carboxaldehyde compounds. Blue-M1 that reacts readily to yellow compounds has a polymerizing activity, suggesting that it is an important Maillard reaction intermediate through the formation of melanoidins. Blue-M1 had strong antioxidative effects as well as melanoidins.