Reactivity of 1-deoxy-D-erythro-hexo-2,3-diulose: a Key Intermediate in the Maillard Chemistry of Hexoses

Degradation of 1-deoxyhexo-2,3-diulose, a key intermediate in Maillard chemistry, in the presence of l-alanine under moderate conditions (37 and 50 degrees C) was investigated. Different analytical strategies were accomplished to cover the broad range of products formed and their differing chemical properties. These involved GC-MS analysis of trimethylsilyl and O-benzyloxime trimethylsilyl derivatives (after reaction with O-benzylhydroxylamine and N,O-bis(trimethylsilyl)acetamide), GC-FID analysis of the decyl ester of acetic acid (after reaction with decyl chloroformate), and HPLC-UV analysis of quinoxaline derivatives (after reaction with o-phenylenediamine). Among the compounds identified were carboxylic acids (glyceric acid and acetic acid) that can be seen as stable Maillard end-products. However, the formation of dicarbonyls (3,4-dihydroxy-2-oxobutanal, 1-hydroxybutane-2,3-dione, and 4-hydroxy-2-oxobutanal) and of hydroxycarbonyls (acetol) was verified presenting unstable, reactive Maillard intermediates. Results confirmed that beta-dicarbonyl cleavage is a very important pathway within the degradation of 1-deoxyhexo-2,3-diulose. Other reactions taking place include enolization, water elimination, and oxidation.