Structures required of polyphenols for inhibiting advanced glycation end products formation.

The properties of polyphenols as AGEs formation inhibitors have attracted great interest among researchers. This review discusses the antiglycation activities of polyphenols and focuses on the relationship between the AGEs formation inhibitory activities and their chemical structures. The molecular structures influence the inhibition in the following ways: (1) The hydroxylation on both A ring and B ring improved the inhibitory activity on AGEs formation, while hydroxylation on C ring decreased the activity. (2) The methylation generally reduced the anti-AGEs activity of flavonoids, except for the 3-O-methylation of flavonols. (3) The glycosylation of hydroxyls of flavonoids tended to decrease the inhibitory activities on inhibiting AGEs formation, although contradictionary results were existed. (4) Hydrogenation of the C2=C3 double bond of flavones slightly weakened their activities. (5) A 5,7-dihydroxy structure was favorable to the activity of isoflavones. (6) Proanthocyanidins dimer or trimers showed a stronger inhibitory activity than catechins, and the glucosides of anthocyanidin had higher activities than their rutinosides. (7) The hydroxylation on B ring and the methylation of stilbenes decreased the inhibitory activity. (8) Presence of galloyl groups was important for the activity of catechins, and α-hydroxyl group at C-3 was much more effective than β-hydroxyl group at C-3. (9) The phenolic acids with multiple hydroxyls showed strong inhibition against AGEs formation, and an ortho or meta dihydroxyl structure on the benzene ring was vital to the anti-AGEs activity of anthraquinone. (10) Both ellagic acids and ellagitannins showed potent inhibitory activities on AGEs formation, and hydroxylation increased the activities but methylation decreased them.