关键词: 丙酮醛；甲醛；氨基酸；γ-氨基丁酸；加合物

Abstract: Methylglyoxal and formaldehyde are harmful substances widely existing in foods and in the human body. This work aimed to evaluate the efficacy and mechanism of action of amino acids in eliminate them. At pH 7.0, different amino acids were reacted with methylglyoxal with a molar ratio of 1:1 at 80 ℃ for 4 h, and residual methylglyoxal was determined using high performance liquid chromatography (HPLC) after derivatization. Among the 14 amino acids investigated, cysteine, γ-aminobutyric acid, and lysine showed the highest ability to eliminate methylglyoxal. γ-Aminobutyric acid, more abundant in foods, was found to be more effective in eliminating methylglyoxal at pH 7.0 than pH 2.0, and the presence of formaldehyde increased the elimination rate to 81%. This effect was more pronounced under thermal conditions (160 ℃). Based on the above results, the reaction product of γ-aminobutyric acid with methylglyoxal and formaldehyde was synthetized and purified. By high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), high-resolution mass spectrometry (HRMS), and nuclear magnetic resonance (NMR), the product was identified as an imidazole salt with a molecular mass of 254.133 9 and a maximum absorption wavelength of 220 nm. It was a nitrogen-containing pentabasic cyclic product formed from two molecules of γ-aminobutyric acid, one molecule of methylglyoxal and one molecule of formaldehyde through nucleophilic addition.

Key words: methylglyoxal; formaldehyde; amino acid; γ-aminobutyric acid; adduct