Enzymatic Degradation of Anthocyanins

Abstract:

The research advances in the enzymes degrading anthocyanins and their degradation mechanisms were summarized. The enzymes degrading anthocyanins include anthocyanase, polyphenol oxidase (PPO), peroxidase (POD) and pectinases. Anthocyanase and pectinase both hydrolyze the glucosidic bond of anthocyanins to produce anthocyanidins and saccharides, anthocyanidins are highly unstable and spontaneously change into colorless derivatives duo to the easy openning of their pyrylium rings. Anthocyanins can not directly act as PPO or POD substrates. The oxidation and degradation of anthocyanins catalyzed by PPO and POD must rely on the presence of other phenolics holding o-diphenol structure, and are realized by a coupled oxidation mechanism of consecutive-type. In the presence of O₂ and H₂O₂, respectively, PPO and POD oxidize other phenolics to o-quinones which oxidize anthocyanins to anthocyanin o-quinones and are reduced back to the native phenolics. Non-enzymatic self-associations happen between the o-quinones and the anthocyanin o-quinones or among the anthocyanin o-quinones, forming melanins. Therefore, the anthocyanins degradation in vivo may be realized by the simultaneous catalyzing of several enzymes, which could provide a reference for the exploration of the in vivo degradation mechanisms of anthocyanins and the artificial regulations of the enzyme activities to stabilize or degrade the anthocyanins.