Identification of key metabolites in fermented quinoa and their α-glucosidase inhibitory mechanisms using widely targeted metabolomics and molecular simulation.

This study systematically analyzed metabolite changes in quinoa after lactic acid bacteria (LAB) fermentation and the hypoglycemic mechanism of key metabolites inhibiting α-glucosidase. Mixed LAB fermentation significantly altered the metabolic profile of quinoa, and a total of 627 differential metabolites were identified, among which 471 were significantly up-regulated. After fermentation, the levels of flavonoids, phenolic acids, and amino acid derivatives increased significantly, and five new flavonoid metabolites were detected. The polyphenol extract from fermented quinoa (FQP) significantly inhibited α-glucosidase activity, with an IC₅₀ value of 0.17 mg/mL. Mechanistic studies indicated that FQP exerted mixed-type reversible inhibition, forming hydrogen bonds, van der Waals forces, and hydrophobic interactions with amino acid residues in the active center of α-glucosidase. These interactions induced conformational changes in the enzyme, thereby reducing its catalytic efficiency. This research provides a theoretical basis for the functional processing of quinoa and the development of novel hypoglycemic functional factors.