Mechanism of reactive carbonyl species trapping by hydroxytyrosol under simulated physiological conditions

This investigation reveals that hydroxytyrosol (HT) could compete with lysine, arginine and histidine to bind methylglyoxal (MGO) and reducing the formation of advanced glycation end products. Kinetic of the degradation of HT in presence/absence of MGO under simulated physiological conditions is monitored by HPLC coupled to a QTOF spectrometer. HT should previously be oxidized to DOPAC (3,4-dihydroxyphenylacetic acid) which reacts with MGO by electrophilic aromatic substitution of the ortho-diphenyl ring. DOPAC was detected as the major degradation product of HT under simulated physiological conditions. Ortho-hydroxyl groups are necessary to promote the nucleophilic addition of MGO by HT and related compounds. The formation of four adducts were described by mass spectrometry, but monoDOPAC-monoMGO adduct (C11H12O6) was predominant. Results suggest that HT and its degradation product DOPAC could have a relevant role in preventing the formation of advanced glycation end products and therefore potentially mitigate the diabetic complications.