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Relationships of dietary flavonoid structure with its tyrosinase inhibitory activity and affinity

Fan, Meihui, Ding, Huafang, Zhang, Guowen, Hu, Xing, Gong, Deming
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2019 v.107 pp. 25-34
amino acids, binding capacity, enzyme inhibition, enzyme inhibitors, enzymes, flavonols, glycosylation, hydrogen bonding, hydrogenation, hydroxylation, methylation
Flavonoids possess the inhibition ability against tyrosinase. Here, the effects of flavonoids structure on inhibitory activity and binding affinity of tyrosinase were investigated. The results showed that the hydroxy groups of 5C−OH, 4′C−OH and 5′C−OH of flavonoids were in favor of forming hydrogen bond with the amino acid residues of tyrosinase, which played a crucial role in the binding and interaction between flavonoids and tyrosinase. Different groups of flavonoids exhibited different influences on tyrosinase inhibitory activity and binding affinity. The hydroxylation at C3′ position of flavonoids increased affinities for tyrosinase, whereas the inhibitory activities went downward and upward for flavone and flavonol, respectively. The hydrogenation of the C2 = C3 double bond of flavones weakened inhibitory activities and strengthened affinities, which increased affinities of flavonols with downward and upward inhibitions. The decreased inhibitory activities and affinities can be realized by the hydroxylation of the C4′ and C5′ of flavonoids. Methylation of flavonoids decreased the inhibition while methoxylation of 5′C increased affinity and methylation of 4’−OH led to an increase in affinity. Glycosylation mainly induced the decline in both inhibitory activities and affinities of flavonoids. These findings may provide useful information for the structural modification of flavonoids as effective tyrosinase inhibitors.