The interaction mechanism of (−)-epigallocatechin gallate (EGCG) with Amadori compound (Amadori rearrangement product, ARP) in xylose−alanine model reaction systems was investigated. The adducts between ARP and EGCG were identified as two ARP−EGCG isomers, two ARP−EGCG−H 2 O isomers, and multiple ARP−deoxypentosone (DP)−EGCG isomers. The structure of an isolated and purified ARP−EGCG adduct was analyzed by means of Fourier transform infrared spectroscopy, ultraviolet−visible spectroscopy, liquid chromatography−time-of-flight (TOF)−mass spectrometry (LC−TOF−MS), and nuclear magnetic resonance (NMR). Using the two-dimensional NMR analyses, the structure of ARP−EGCG adducts was clarified to consist of a covalent linkage between the C 12 position of the ARP and the C 8 position of the A-ring of EGCG, presumably generated by the nucleophilic nature of the EGCG or aromatic substitution reactions. The results showed that slightly alkaline pH and higher temperature could facilitate this reaction. Additionally, the thermal stability of ARP−EGCG and its degradation products revealed that the decomposition pathways of this adduct altered the classic decomposition pathway of ARP, resulting in a lower browning rate and blocking the subsequent Maillard reaction.

The implicit membrane model IMM1 is extended to include the membrane dipole potential and applied to molecular dynamics simulations of the helical peptides alamethicin, WALP23, influenza hemagglutinin fusion peptide, HIV fusion peptide, magainin, and the pre-sequence of cytochrome c oxidase subunit IV (p25). The results show that the orientation of the peptides in the membrane can be influenced by the dipole potential. The binding affinity of all peptides except for the hemagglutinin fusion peptide decreases upon increase of the dipole potential. The changes in both orientation and binding affinity are explained by the interaction of the dipole potential with the helix backbone dipole and ionic side-chains. In general, peptides that tend to insert the N-terminus in the membrane and/or have positively charged side chains will lose binding affinity upon increase of the dipole potential.

The inhibitory effects of glutathione (GSH) and oxiglutathione (GSSG) on Maillard browning were compared, and it was clarified that free sulfhydryl was the key substance for the inhibition. The Amadori rearrangement product (ARP) derived from glycylglycine (Gly-Gly) and arabinose (Ara) was prepared by aqueous Maillard reaction, and LC-MS/MS was used to investigate the reaction products of GSH and purified ARP. Reaction between GSH and deoxypentosone (DP) was found to alter the pathway of aqueous Maillard reaction, which reduced the production of glyoxal, methylglyoxal, and furfural and thereby inhibited the formation of melanoidins. To determine the optimal conditions for browning inhibition, a stepwise increase of temperature was used to prepare Maillard reaction products (MRPs). The results showed that the optimum browning inhibitory effect was obtained by adding GSH after Gly-Gly and Ara heating at 80 °C for 60 min.