Inhibition The Advanced Glycation End Products Of Food Natural Antioxidants In Vitro

Advanced glycation end products(AGEs) are some of the products of the Maillardreaction. Lipid peroxidation and glucose oxidation can also produce AGEs. AGEs have beenimplicated in diseases, such as diabetes, kidney disease, atherosclerosis. Dietary AGEs are animportant source of in vivo AGEs.The aim of this study was to investigate the inhibitoryeffects of three natural antioxidants on the formation of AGEs and their inhibitory mechanismusing a BSA-Glucose model system. The model system of bovine serum albumin–glucosewas employed and tea polyphenols, licorice extract, and rosemary extract were used asinhibitors. Aminoguanidine (AG) was used as a positive control. All samples were incubatedfor7,14,21,28days at37℃. Fluorescence intensity was used to measure total AGE content.Additionally, protein thiol, carbonyl content, and free radical scavenging activities were alsodeterminated, and molecule weights were determined with SDS-PAGE. AGEs cross-linkswere examined to identify the mechanism of AGEs inhibitory effect of three natural foodantioxidants, which could contribute to further study of AGEs formation and control in food.The main results of this study are as follows:(1) In the BSA-Glucose model system, AGEs content increased with extended reactiontime. Statistically significant differences were found between different reaction days (P<0.01). All three antioxidants significantly inhibited AGEs formation between bovine serumalbumin and glucose in a concentration-dependent manner. When rosemary concentrationwas200μg/mL, the inhibition rate reached87.79%at28days incubation, followed bylicorice extract and tea polyphenols, with the inhibition rates of83.56%and81.03%respectively, which was more than aminoguanidine(69.15%) as positive control.(2) After14days incubation in the BSA-Glucose system, protein carbonylconcentration decreased and protein thiol concentration gradually increased with teapolyphenols concentration varying from50to200μg/mL. At200μg/mL concentration of teapolyphenols, protein carbonyl and the thiol content were6.47nmol/mg and1.38mmol/L,respectively, which showed significant differences to the control group. (3) The results for free radical scavenging activity showed that the IC50value was14.84mg/L by DPPH method. ABTS method obtained IC50value for ABTS free radicalscavenging activity of6.92mg/L and TEAC was15.01mmoLTrolox/g tea polyphenols.Fenton reaction producing hydroxyl radical promoting the formation of AGEs, would onepossible explanation.With a concentration of100μg/mL tea polyphenols, AGEs contentdecreased and there was a significant difference between the test group and the control group.Tea polyphenols might inhibit the formation of AGEs by scavenging free radical.(4)Using SDS-PAGE to analyse the change of protein molecular weight inBSA-Glucose system after14days incubation, the molecular weight of BSA graduallydecreased as the concentration of tea polyphenols increased, but never as low as BSA controlgroup. This shows that tea polyphenols can prevent the cross-linking between proteins, andprevent the formation of AGEs.