Effects Of Food Antioxidants On The Formation Of AGEs From Protein Glycosylation

The non-enzymatic glycosylation(Maillard reaction)is commonly occurring in vivo and foods,which leads to the formation of advanced glycation endproducts(AGEs).The AGEs are divided into endogenous and exogenous.AGEs from vitro and foods are named exogenous AGEs.AGEs have close relationships to human aging and diseases.In this paper,the effects of food antioxidants on the formation of AGEs during glycosylation were investigated.Eight food antioxidants were chosen as experimental materials and different amino acid and protein glycosylation reaction model system were established.The selected antioxidants were grape seed extract(hereinafter referred to as proanthocyanidins),pueraria extract(hereinafter referred to as pueraria flavonoids),cinnamon extract(hereinafter referred to as cinnamon flavonoids),green tea extract(hereinafter referred to as tea polyphenols),citric acid,ascorbic acid,EDTA-Na₂,sodium phytate.Lysine,glutamic acid,glycine,mixed amino acids(lysine:glutamic acid:glycine=1:2:2)and BSA,gelatin,casein sodium salt,egg albumin were used to simulate the protein glycosylation reactions.Firstly,antioxidant activities of eight food antioxidants were detected,and total phenolic content and total flavonoid content were measured of the natural antioxidants.At the same concentration,total reducing powers were ranked in turn:tea polyphenols>proanthocyanidins>ascorbic acid>citric acid>pueraria flavonoids>cinnamon flavonoids>edetate disodium>sodium phytate.Scavenging effects on free group of antioxidants by DPPH radical method were ranked in turn:ascorbic acid>tea polyphenols>proanthocyanidins>pueraria flavonoids>cinnamon flavonoids>sodium phytate>citric acid>edentate disodium.As for the total phenol content,the green tea extract was higher than that of the grape seed extract;as for the total flavonoid content,the pueraria extract was higher than that of the cinnamon extract.Secondly,different amino acids and protein glycosylation reaction model systems were established.Using 50 mmol/L lysine,glutamic acid,glycine and mixed amino acids(lysine:glutamic acid:glycine=1:2:2)respectively reacted with 250 mmol/L glucose at 37?for 14 days,55?for 24 hours and 90?for 4 hours to simulate the amino acid glycosylation reactions in vivo,in moderate heated and high-temperature heated foods.Using 50 mg/m L BSA reacted with 20 mg/m L glucose at 37?for 14days to simulate the protein glycosylation reactions in vivo.Using 10 mg/m L gelatin,casein sodium salt,egg albumin reacted with 100 mg/m L glucose at 55?for 24 hours to simulate the protein glycosylation reactions of the moderate heated animal derived foods.Thirdly,the single antioxidants which had inhibiting effect on fluorescent AGEs in each model system were screened.And whether the inhibitory effect of fluorescent AGEs and the concentrations of antioxidants had dose-effect relationship were explored.Five kinds of antioxidants which had dose-effect relationship were selected for orthogonal test.The obtained results of the composite antioxidants were as following:At 37?,the suitable antioxidants combination of mixed amino acids glycosylation system was 2 mg/m L proanthocyanidins,2 mg/m L pueraria flavonoids,0.25 mg/m L ascorbic acid,0.1 mg/m L tea polyphenols.The inhibition rates of fluorescence AGEs and pentosidine were 99.77%and 79.34%respectively.The suitable antioxidants combination of BSA glycosylation system was 2 mg/m L proanthocyanidins,2 mg/m L cinnamon flavonoids,0.4 mg/m L tea polyphenols.The inhibition rates of fluorescence AGEs and pentosidine were 98.67%and 70.44%respectively.At 55?,the suitable antioxidants combination of mixed amino acids glycosylation system was 2 mg/m L proanthocyanidins,2 mg/m L pueraria flavonoids,0.5 mg/m L cinnamon flavonoids,0.4 mg/m L tea polyphenols.The inhibition rates of fluorescence AGEs and pentosidine were 99.82%and 73.14%respectively.The suitable antioxidants combination of gelatin glycosylation system was 0.5 mg/m L proanthocyanidins,2mg/m L pueraria flavonoids,0.5 mg/m L cinnamon flavonoids,0.2 mg/m L tea polyphenols.The inhibition rates of fluorescence AGEs and pentosidine were 83.23%and 89.46%respectively.The suitable antioxidants combination of casein sodium salt glycosylation system was 2 mg/m L proanthocyanidins,2 mg/m L citric acid,0.2 mg/m L tea polyphenols.The inhibition rates of fluorescence AGEs and pentosidine were97.43%and 74.32%respectively.The suitable antioxidants combination of egg albumin glycosylation system was 2 mg/m L proanthocyanidins,0.4 mg/m L tea polyphenols.The inhibition rates of fluorescence AGEs and pentosidine were 80.53%and 86.24%respectively.When the mixed antioxidants were added to protein glycosylation reaction model system,except fructosamine content decreased,the content of carbony,sulfydryl,foaming power and stability had no significant differences to the group of non-added antioxidants.