In vitro evaluation of the inhibitory effect of phenolic acids on protein glycation: A potential strategy for reducing diabetic complications

Abstract

Advanced glycation end-products are harmful compounds formed through non-enzymatic reactions between sugars and proteins. Their accumulation, particularly under hyperglycemic conditions, contributes significantly to oxidative stress and chronic complications in diabetes mellitus. Natural compounds with antioxidant and antiglycation properties, such as phenolic acids, are increasingly being investigated as preventive agents. This study aimed to evaluate and compare the inhibitory effects of ferulic acid and gallic acid on AGE formation and oxidative protein damage in an in vitro bovine serum albumin (BSA) glucose model as a potential strategy to mitigate diabetes-related complications. BSA was incubated with 1.10 M glucose at 37 °C for 2, 4, and 6 weeks, with or without phenolic acids (gallic acid or ferulic acid) at various concentrations (1-10 µM). The formation of fluorescent Advanced glycation end-products was assessed using Spectrofluorometry (Ex/Em: 360/460 nm), while protein carbonyl content-an indicator of oxidative damage-was measured via the DNPH assay (absorbance at 375 nm). Gallic acid and ferulic acid significantly reduced AGE fluorescence and protein carbonylation compared to the glycated control. Gallic acid showed more consistent inhibition across most time points and concentrations. Ferulic acid was less effective at earlier stages but exhibited delayed protective effects at week six. The difference in inhibitory activity may be attributed to structural variations, particularly the number and position of hydroxyl groups influencing BSA binding affinity. Gallic acid demonstrated superior antiglycation and antioxidant effects compared to ferulic acid under identical experimental conditions. These findings support the potential application of phenolic acids as natural inhibitors of glycation-related protein damage.