Augmentation of α-amylase and α-glucosidase inhibitory properties of Callerya speciosa root extracts: An exploration through simulated human gastrointestinal digestion

Abstract

The present work represents the first effort to evaluate the effect of an in vitro simulated human digestion model on the α-amylase and α-glucosidase inhibitory activities of Callerya speciosa root extracts. Through bioguided fractionation, a series of fractions were obtained from hexane (CSH) and ethyl acetate (CSE) extracts. Initial screening identified active fractions (CSH2, CSH3, CSE2, CSE3, and CSE4) for further in vitro digestion evaluation. The results showed a decrease in antioxidant activity across all samples after digestion, while a simultaneous increase in α-amylase and α-glucosidase inhibitory activities was observed during the small intestinal phase. Notably, compared with the undigested fraction, CSE3 demonstrated a 1.7-fold increase in α-amylase inhibition (IC50 = 0.86 mg/mL). Moreover, the α-glucosidase inhibitory activities of CSH3, CSE3, and CSE4 were significantly greater after digestion, with IC50 values of 0.18, 0.05, and 0.02 mg/mL, respectively. Impressively, during the small intestinal phase, the α-glucosidase inhibitory activities of CSH3, CSE3, and CSE4 were substantially greater than those of acarbose by 13.2-, 47.6-, and 119.0-fold, respectively, and greater than those of palmitic acid by 1.7-, 6.0-, and 15.0-fold, respectively. GC-MS and LC-ESI-MS/MS analyses identified isoflavonoids, fatty acids, and triterpenoids as key bioactive compounds in these fractions. The present work provided foundational insights for the future exploration of C. speciosa root extracts for diabetes management.