Mechanistic insights into advanced glycation end products production in glucose-lysine model system involved with ascorbic acid.

Ascorbic acid (AA), despite being an essential vitamin, is also a potential precursor to form advanced glycation end products (AGEs) in heat-processed foods. The dual action of AA (act as an inhibitor and a precursor concurrently) in AGEs formation in glucose (Glu)-lysine (Lys) model system has been found in our previous study. However, the mechanism underlying the dual role of AA has not been elucidated. This study clarified that AA, when acting as an inhibitor, primarily suppresses AGEs formation via its pH-regulating capacity rather than its reductive (free radical scavenging) potential. When AA serves as a substrate, its reactivity to form AGEs depends on pH condition. We further elucidated the primary pathways of AA-mediated AGEs formation. Methylglyoxal (MGO), generated via 2,3-diketoglucose (2,3-DKG), remains the principal intermediate for CEL formation from AA. Xylosone, a highly reactive carbonyl compound derived from AA, emerges as the major intermediate for CML formation.