Polyphenol Profile and In Vitro Antioxidant and Enzyme Inhibitory Activities of Different Solvent Extracts of Highland Barley Bran

Five different solvent extracts of highland barley bran were analyzed and compared for their polyphenol profile, antioxidant activity, and alpha-glucosidase and alpha-amylase inhibitory activities. The highland barley bran acetone extract had the highest total phenolic content, total flavonoid content, and antioxidant capacity. It was followed by the methanol and ethanol extracts, while n-butanol and ethyl acetate extracts exhibited lower measured values. Diosmetin, luteolin, protocatechuic acid, vanillic acid, ferulic acid, phlorogucinol, diosmin, isoquercitrin, catechin, and isovitexin were among the most abundant phenolic compounds identified in different solvent extracts, and their concentrations varied according to the solvent used. The highest alpha-glucosidase and alpha-amylase inhibitory activity were observed in the ethyl acetate extract of highland barley bran, followed by the acetone and methanol extracts. In contrast, n-butanol and ethanol extracts exhibited lower measured values. The different solvent extracts were effective inhibitors for alpha-glucosidase and alpha-amylase with activity reaching to 34.45-94.32% and 22.08-35.92% of that of positive control acarbose, respectively. There were obvious correlations between the phenolic content and composition of different solvent extracts and their in vitro antioxidant activity, alpha-glucosidase inhibition activity and alpha-amylase inhibition activity. Black barley bran is an excellent natural raw material for developing polyphenol-rich functional foods and shows good antioxidant and hypoglycemic potential to benefit human health.

Automated summary

Five different solvent extracts of highland barley bran were analyzed and compared for their polyphenol profile, antioxidant activity, and enzyme inhibitory activities. The acetone extract had the highest content of phenolic compounds, flavonoids, and antioxidant capacity. The ethyl acetate extract exhibited the highest inhibitory activity against alpha-glucosidase and alpha-amylase enzymes. Black barley bran is a valuable raw material for the development of polyphenol-rich functional foods with antioxidant and hypoglycemic potential.