Alpha-glucosidase inhibitory activity in different pepper cultivars (Capsicum annuum L.)

The number of cases of type II diabetes has increased dramatically worldwide. Plant-based foods offer some options for treating this disease. Effective diabetes prevention is achieved by controlling postprandial hyperglycemia by α-glucosidase inhibition. This study investigated the α-glucosidase inhibitory activity of extracts of 14 cultivars of pepper fruits (Capsicum annuum L.), which are widely consumed in Korea. Pepper fruit extracts were prepared with 70% ethanol and water, and diluted to 50% and 25% strengths before performing an α-glucosidase inhibition assay. No significant differences in α-glucosidase inhibitory activity were found between the two different aqueous extracts. Mee-In and Dda-Go-Ddo-Dda-Go cultivars had the highest and most sustained inhibitory activity (almost 100%) against α-glucosidase. In contrast, while extracts from Soon-Han-Gil-Sang, Gil-Sang, Sweety, Hyul-Jo K, Shin-Hong, and Ai-Mat inhibited α-glucosidase activity, the level of inhibition sharply decreased with decreasing extract concentrations between100% and 50%. The results of this study suggest the possible existence of unknown inhibitors that are present at different concentrations in different pepper cultivars. Further studies are required to identify the unknown enzymes that are key to α-glucosidase inhibition in pepper fruits.