In Vitro Inhibitory Mechanism of Polyphenol Extracts from Multi-Frequency Power Ultrasound-Pretreated Rose Flower Against α-Glucosidase

This paper explored the in vitro inhibitory mechanism of polyphenol-rich rose extracts (REs) from an edible rose flower against α-glucosidase using multispectral and molecular docking techniques. Results showed that REs had an inhibitory effect on α-Glu activity (IC₅₀ of 1.96 μg/mL); specifically, the samples pretreated by tri-frequency ultrasound (20/40/60 kHz) exhibited a significantly (<i>p</i> < 0.05) stronger inhibitory effect on α-Glu activity with an IC₅₀ of 1.33 μg/mL. The Lineweaver-Burk assay indicated that REs were mixed-type inhibitors and could statically quench the endogenous fluorescence of α-Glu. REs increased the chance of polypeptide chain misfolding by altering the microenvironment around tryptophan and tyrosine residues and disrupting the natural conformation of the enzyme. Molecular docking results showed that polyhydroxy phenolics had a high fit to the active site of α-Glu, so REs with high polymerization and numerous phenolic hydroxyl groups had a stronger inhibitory effect. Therefore, this study provides new insights into polyphenol-rich REs as potential α-glucosidase inhibitors.