Inhibitory effects of Gymnema inodorum (Lour.) Decne leaf extracts and its triterpene saponin on carbohydrate digestion and intestinal glucose absorption.


Srinuanchai W(1), Nooin R(1), Pitchakarn P(2), Karinchai J(2), Suttisansanee U(3), Chansriniyom C(4), Jarussophon S(1), Temviriyanukul P(3), Nuchuchua O(5).
Author information:
(1)National Nanotechnology Center
(NANOTEC), National Science and Technology Development Agency
(NSTDA), Pathum Thani, Thailand.
(2)Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
(3)Institute of Nutrition, Mahidol University, Nakhon Pathom, Thailand.
(4)Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand; Natural Products and Nanoparticles Research Unit, Chulalongkorn University, Bangkok, Thailand.
(5)National Nanotechnology Center
(NANOTEC), National Science and Technology Development Agency
(NSTDA), Pathum Thani, Thailand. Electronic address: [Email]


ETHNOPHARMACOLOGICAL RELEVANCE: Chiang-Da, Gymnema inodorum (Lour.) Decne. (GI), is an ethnomedicinal plant that has been used for diabetic treatment since ancient times. One of the anti-diabetic mechanisms is possibly related to the actions of triterpene glycoside, (3β, 16β)-16,28-dihydroxyolean-12-en-3-yl-O-β-D-glucopyranosyl-β-D-glucopyranosiduronic acid (GIA1) in decreasing carbohydrate digestive enzymes and intestinal glucose absorption in the gut system. AIMS OF THE STUDY: To observe the amount of GIA1 in GI leaf extracts obtained from different ethanol concentrations and to investigate the anti-hyperglycemic mechanisms of the extracts and GIA1. MATERIALS AND METHODS: The crude extracts were prepared using 50%v/v to 95%v/v ethanol solutions and used for GIA1 isolation. The anti-hyperglycemic models included in our study examined the inhibitory activities of α-amylase/α-glucosidase and intestinal glucose absorption related to sodium glucose cotransporter type 1 (SGLT1) using Caco-2 cells. RESULTS: GIA1 was found about 8%w/w to 18%w/w in the GI extract depending on ethanol concentrations. The GI extracts and GIA1 showed less inhibitory activities on α-amylase. The extracts from 75%v/v and 95%v/v ethanol and GIA1 significantly delayed the glycemic absorption by lowering α-glucosidase activity and glucose transportation of SGLT1. However, the 50%v/v ethanolic extract markedly decreased the α-glucosidase activity than the SGLT1 function. CONCLUSION: Differences in the GIA1 contents and anti-glycemic properties of the GI leaf extract was dependent on ethanol concentrations. Furthermore, the inhibitory effects of the 75%v/v and 95%v/v ethanolic extracts on α-glucosidase and SGLT1 were relevant to GIA1 content.