Flavonoids inhibiting glycation of bovine serum albumin: affinity-activity relationship

Protein glycation leads to the formation of advanced glycation end-products (AGEs), which contribute to the pathogenesis of diabetic complications. The structure-activity relationship of dietary flavonoids for inhibiting the glycation of bovine serum albumin (BSA) in vitro was subjected to a detailed investigation. The structure-activity relationship revealed that: 1) the hydroxylation on ring B of the flavones enhanced the inhibition and the hydroxyl groups at the C-5 and C-7 positions of flavones favoured the inhibition; 2) the optimal number of hydroxyl groups on ring B of the flavonols was one (at the C-3 position) and the methylation of flavonols weakened the inhibition; 3) the methoxylation at the C-6 position and methylation at C-4′ position of genistein clearly enhanced the inhibition; 4) the hydroxyl groups at the C-5 and C-7 positions of flavanones were in favour of the inhibition; 5) the glycosylation of flavonoids significantly weakened the inhibition. Obvious linear affinity-activity relationships exist between the BSA-flavonoid interaction and flavonoids as BSA glycation inhibitors (R2 = 0.76585). The flavonoids with a higher affinity to BSA exhibited a stronger inhibition of the glycation of BSA.