Reactivity of 1-Deoxy-d-erythro-hexo-2,3-diulose: A Key Intermediate in the Maillard Chemistry of Hexoses

Abstract

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.

Pathways of the Maillard reaction under physiological conditions

“…Again, Davidek et al were the first to perform detailed mechanistic studies [72,73]. The results were confirmed by investigations of our workgroup [74,75]. We studied the degradation of 1-DG which is isomerized into its 2,4-tautomer.…”

Extending the Spectrum of α-Dicarbonyl Compounds in Vivo

“…As established in previous papers of our group (39,66), the C 4 -dicarbonyls threosone, 1-DT, and 3-DT are formed from both 1-DG and 2,3-DKG via ␤-dicarbonyl cleavage with an C 4 -enediol as the reactive intermediate. Oxidation of the latter leads to threosone, whereas dehydration at C3 results in 3-DT.…”

Changes in Maillard reaction products in ghee during storage

“…1) regenerates the highly reactive 1-deoxyglucosone (Kim & Baltes, 1996;Voigt et al, 2010). The reactive 1-deoxyglucosone, depending on the conditions, can then form numerous compounds including acetic acid (Voigt & Glomb, 2009;Voigt et al, 2010). It is likely that water addition to DHHD can also regenerate 1-deoxyglucosone (and again, this could then proceed to acetic acid).…”

“…1) to produce 5 and 6-membered ring compounds, such as acetylformoin (right branch of Fig. 1) and 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (pyranone), respectively (Kim & Baltes, 1996;Voigt & Glomb, 2009;Voigt, Smuda, Pfahler, & Glomb, 2010). Acetylformoin is notable in that it has a linear tautomer (3,4-dihydroxy-3-hexen-2,5-dione, DHHD, Fig.…”

“…For example, pyranone (Kim & Baltes, 1996), acetylformoin (Hofmann, 1998), and 1-deoxyglucosone (Davidek, Robert, Devaud, Vera, & Blank, 2006;Voigt & Glomb, 2009;Voigt et al, 2010) have all been shown to produce the same numerous end products of glucose degradation. Furthermore, pyranone and DHHD formed compounds (e.g., acetic acid, formic acid, lactones) that are best explained by conversion to deoxyglucosone followed by hydrolytic and oxidative fragmentation.…”