Free phenolics(FP),esterified phenolics(EP),glycosidized phenolics(GP)and insoluble bound phenolics(IBP)were successively extracted from two varieties of peony flowers:Danfeng and Xiangyu.The contents of total phenolics,total flavonoids and the major components in different phenolics fractions were determined,and their antioxidant activity and α-glucosidase inhibitory activity were also studied.It was found that for the two varieties,the contents of total phenols(31.45 and 32.64 mg/g,respectively)and total flavonoids(41.11 and 40.67 mg/g,respectively)in FP were both the highest,followed by EP and GP,and the lower values were found in IBP.Each of the two FPs contained 17 components,with the major ones being resveratrol,1,2,3,4,6-O-pentagalloylglucose and apigetrin.The major components of EP and GP were kaempferol-7-O-β-D-glucoside and apigetrin.The antioxidant activity of FP was the strongest among the four phenolics fractions.The l,l-diphenyl-2-trinitrophenylhydrazine(DPPH),2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)cation radical scavenging capacity and ferric reducing power of FP were 855.03,367.10,and 230.54 μmol/g for Danfeng,and 499.06,290.64,and 196.39 μmol/g for Xiangyu,respectively.For both varieties,FP exhibited the strongest inhibitory activity against α-glucosidase with half maximal inhibitory concentrations of 12.15 and 13.87 μg/mL,respectively.The research results are of reference significance for the utilization of polyphenols in Danfeng and Xiangyu.
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