DETERMINATION OF THE KINETICS AND MECHANISM OF DECOMPOSITION OF TRYPTOPHAN AMADORI REARRANGEMENT PRODUCT BY RP-HPLC ANALYSIS

Tryptophan Amadori rearrangement product (ARP) was synthesized, and its decomposition was studied at two different temperatures and concentrations over a period of 6 h. RP-HPLC analysis of the reaction mixtures indicated the presence of hydroxymethylfurfural (HMF), maltol, tryptophan, indole, norharman and harman. Kinetic analysis showed that the activation energy (E(a)) for the decomposition of ARP and for the formation of maltol from ARP depended on the water content of the reaction mixture; on the other hand, the E(a) (4.1 kcal/mol) for the formation of HMF from the ARP was independent of the water content. A comparative study of the formation of HMF and maltol from ARP and from glucose alone showed that the Amadori rearrangement provides a low-energy pathway for the formation of these two compounds. The kinetic data were used to propose plausible mechanisms for the decomposition of the ARP.