α-Amylase inhibitory effects of hydroethanolic extract from seven plants commonly used for Type-II diabetes treatment in Burkina Faso

Abstract

Natural α-amylase inhibitors may be beneficial in reducing the release of oligosaccharides from starch and thereby delaying glucose absorption. This research aimed to evaluate the inhibitory effect against α-amylase and the inhibition mode of hydroethanolic extracts from seven plants traditionally used in the treatment of type II diabetes. In this study, phenolic compounds were quantified, and the antioxidant activities of the extracts were determined in terms of their free radical scavenging capacity and iron-reducing power. Their ability to inhibit porcine pancreatic α-amylase in vitro was tested, and the inhibition modes were determined from the Lineweaver-Burk plot. Results showed that all studied plants exerted inhibition against α-amylase. The lowest median inhibitory concentrations (IC50 values) were obtained with C. occidentalis (0.031 μg/mL) and S. bicolor (0.036 μg/mL), showing that they are the most effective. C. sinensis showed the greatest flavonoid content (13.89 μg/100 mg). Enzyme kinetics showed an uncompetitive and non-competitive type of inhibition. Principal component analysis revealed chemical proximity between Sorghum bicolor and Cassia occidentalis. Both extracts were positively associated with high phenolic content and low IC₅₀ values. Therefore, S. bicolor stems and C. occidentalis leaves, used separately, could contribute to the reduction of postprandial blood glucose by inhibiting α-amylase activity.