Study on extraction and purification of flavonoids from corn silk and its inhibitory effect on starch digestive enzymes

Postprandial hyperglycemia represents a critical challenge for individuals with diabetes. Inhibiting the activity of digestive enzymes can effectively delay starch digestion, thereby regulating postprandial blood glucose levels.Crude flavonoids were extracted from corn silk and subsequently purified using AB-8 macroporous resin and polyamide resin for fractionation.Their composition was analyed using liquid chromatography, and their inhibitory activity against α-amylase and α-glucosidase was investigated through kinetic and fluorescence spectroscopy methods. Results demonstrate that the purity of flavonoids increased from 5.16% to 23.19% after purification with AB-8 resin and further rose to 38.42% after purification with polyamide resin, representing a 7.4- fold enhancement. Liquid chromatography analysis revealed that polyamide purification II constituted the primary flavonoid component.Inhibition assays indicated that polyamide-purified flavonoids exhibited the strongest inhibitory effects, with IC50 values of 0.768 mg/mL and 0.017 mg/mL for α-amylase and α-glucosidase,respectively.Kinetic parameters revealed that the Kic values of polyamide-purified flavonoids for α-amylase and α-glucosidase were 4.02 mg/mL and 0.45 mg/mL, respectively, indicating stronger inhibitory activity against α- glucosidase.Spectroscopic analysis suggests that inhibition was primarily achieved through hydrogen bonding, hydrophobic interactions, and van der Waals forces. In summary, flavonoids derived from corn silk demonstrate significant potential to inhibit starch digestive enzymes and may be utilized to assist in the regulation of postprandial blood glucose levels.