Glutathione inhibited starch digestion: Structural and kinetic analysis of substrate and α-amylase

Glutathione (GSH) is a natural antioxidant that helps fight free radicals. Whether it will affect the activity of amylase and starch digestion remains unknown. This research disclosed that GSH could interact with starch through hydrogen bonds, which accelerated the swelling of starch granules and promoted the formation of ordered double-helix crystalline, and therefore inhibited starch digestion. Moreover, pig pancreas α-amylase (PPA) which was incubated with GSH displayed a less stable conformation and decreased activity. However, in a crowded media constructed by sodium caseinate (NaCas), an antagonistic effect existed between GSH and NaCas. As the rate and extent of starch digestion have been linked with health aspects, this study suggests that GSH can be used in the formulation of diet foods. It also reminds us to consider the synergistic or antagonistic effects caused by the coexisted components in the complexed food matrix.