Inhibitory actions of Pseuderanthemum palatiferum (Nees) Radlk. Leaf ethanolic extract and its phytochemicals against carbohydrate-digesting enzymes

ABSTRACT

Objective: To investigate the effects of the leaf ethanolic extract of Pseuderanthemum palatiferum (PPE) and its isolated phytochemicals, stigmasterol and sitosterol-3-O-β-. d-glucopyranoside, against α-amylase and α-glucosidase enzyme activities both in vitro and in vivo. Methods: A concentration of maltose, which is a product released in α-amylase-catalyzing reaction, was used as an index of in vitro α-amylase activity. Meanwhile, in vitro α-glucosidase enzyme activity was indicated by the amount of liberated p-nitrophenol in α-glucosidase-catalyzing reaction. In vivo α-amylase and α-glucosidase enzyme activities were evaluated in the normal rats by using oral starch tolerance test and oral sucrose tolerance test, respectively. Results: PPE exerted a concentration-dependent inhibitory action against both α-amylase and α-glucosidase in vitro with the IC