In Vitro and In Vivo Hypoglycaemic Effect of Camellia Sinensis on Alpha Glucosidase Activity and Glycaemic Index of White Bread

Abstract

High glycaemic index diet and α-glucosidase activity have been implicated in postprandial hyperglycaemia. Regulation of α-glucosidase activity and high glycaemic index diet has promising consequence on curbing the prevalence of type-2 diabetes mellitus. The present study investigated inhibitory effect of aqueous extract of Camellia sinensis (green tea) on α-glucosidase activity and glycaemic index of white bread. In vitro inhibition of α-glucosidase activity using p-nitrophenyl glucopyranoside as substrate and Camellia sinensis aqueous extract as inhibitor was investigated. Likewise, in vivo study on effect of the tea on glycaemic index of white bread using 30 healthy participants was carried out. The outcomes of the investigation revealed that Camellia sinensis aqueous extract reduced the activity of α-glucosidase to 17.50% with IC50 of 202.12 µg/mL. The mode of inhibition was mixed competitive. It also lowered the glycaemic index (GI) of white bread by 39.71% when bread consumption was delayed for 5 minutes after the extract consumption. In conclusion, report has shown that agent that reduces postprandial hyperglycaemia has an important role to play in the handling type-2 diabetes mellitus. This agent does this by lowering the GI of carbohydrate-rich food and/or inhibiting the activities of α-glucosidase enzyme. This study shows that aqueous extract of Camellia sinensis has a great potential to reduce the undue postprandial hyperglycaemia.