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

  • J Ethnopharmacol. 2021 Feb 10;266:113398. doi: 10.1016/j.jep.2020.113398.
Wanwisa Srinuanchai  1 ,  Rawiwan Nooin  1 ,  Pornsiri Pitchakarn  2 ,  Jirarat Karinchai  2 ,  Uthaiwan Suttisansanee  3 ,  Chaisak Chansriniyom  4 ,  Suwatchai Jarussophon  1 ,  Piya Temviriyanukul  3 ,  Onanong Nuchuchua  5
Affiliations
  • 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 protected].
PMID: 32971162 DOI: 10.1016/j.jep.2020.113398
Abstract

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.

Keywords
Ethanol concentration; Gymnema inodorum leaf extract; Sodium glucose cotransporter type 1; Triterpenoid saponin content; α-amylase; α-glucosidase.
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