The degradation and antioxidant activities of capsaicinoid pungent dietary components from peppers and gingers: The mechanistic insights

To mature understand the antioxidant and degradation performances of capsaicinoids from peppers and gingers, the mechanistic insights into the structural changes of 14 capsaicinoids in four types have been elucidated computationally. Our results have revealed the crucial reactive structural sites/areas responsible for their degradation. Capsaicinoids may act as good antioxidants thermodynamically favorably via hydrogen atom donating and radical scavenging routes, where the phenolic O-H and allylic/benzylic C-H bonds are responsible for the hydrogen atom transfer mechanism, and the lipid chain C=C bonds favor the radical adduct formation mechanism. Besides, capsaicinoids seem relatively good electron donors but bad acceptors in their single electron transfer reactions with hydroperoxyl radicals. Furthermore, the photochemical degradation of shogaol-type and gingerol-type cases could be more favorable than that of capsiate-type and capsaicin-type ones. In addition, the solvent effects on the above properties are significant. Finally, the degradation mechanisms in the antioxidant processes have been proposed. Our results would be useful for understanding of their structural changes during the process of the pungent foods.