Diosgenin from Dioscorea bulbifera: novel hit for treatment of type II diabetes mellitus with inhibitory activity against α-amylase and α-glucosidase

PLoS One. 2014 Sep 12;9(9):e106039. doi: 10.1371/journal.pone.0106039. eCollection 2014.

Abstract

Diabetes mellitus is a multifactorial metabolic disease characterized by post-prandial hyperglycemia (PPHG). α-amylase and α-glucosidase inhibitors aim to explore novel therapeutic agents. Herein we report the promises of Dioscorea bulbifera and its bioactive principle, diosgenin as novel α-amylase and α-glucosidase inhibitor. Among petroleum ether, ethyl acetate, methanol and 70% ethanol (v/v) extracts of bulbs of D. bulbifera, ethyl acetate extract showed highest inhibition upto 72.06 ± 0.51% and 82.64 ± 2.32% against α-amylase and α-glucosidase respectively. GC-TOF-MS analysis of ethyl acetate extract indicated presence of high diosgenin content. Diosgenin was isolated and identified by FTIR, 1H NMR and 13C NMR and confirmed by HPLC which showed an α-amylase and α-glucosidase inhibition upto 70.94 ± 1.24% and 81.71 ± 3.39%, respectively. Kinetic studies confirmed the uncompetitive mode of binding of diosgenin to α-amylase indicated by lowering of both Km and Vm. Interaction studies revealed the quenching of intrinsic fluorescence of α-amylase in presence of diosgenin. Similarly, circular dichroism spectrometry showed diminished negative humped peaks at 208 nm and 222 nm. Molecular docking indicated hydrogen bonding between carboxyl group of Asp300, while hydrophobic interactions between Tyr62, Trp58, Trp59, Val163, His305 and Gln63 residues of α-amylase. Diosgenin interacted with two catalytic residues (Asp352 and Glu411) from α-glucosidase. This is the first report of its kind that provides an intense scientific rationale for use of diosgenin as novel drug candidate for type II diabetes mellitus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catalytic Domain
  • Circular Dichroism
  • Diabetes Mellitus, Experimental / drug therapy*
  • Diabetes Mellitus, Experimental / enzymology*
  • Diabetes Mellitus, Experimental / pathology
  • Dioscorea / chemistry*
  • Diosgenin / chemistry
  • Diosgenin / pharmacology
  • Diosgenin / therapeutic use*
  • Enzyme Inhibitors / isolation & purification
  • Enzyme Inhibitors / pharmacology
  • Enzyme Inhibitors / therapeutic use*
  • Intestines / enzymology
  • Kinetics
  • Mice
  • Molecular Docking Simulation
  • Plant Extracts / pharmacology
  • Plant Extracts / therapeutic use
  • Protein Binding / drug effects
  • Spectrometry, Fluorescence
  • Sus scrofa
  • alpha-Amylases / antagonists & inhibitors*
  • alpha-Amylases / metabolism
  • alpha-Glucosidases / metabolism*

Substances

  • Enzyme Inhibitors
  • Plant Extracts
  • alpha-Amylases
  • alpha-Glucosidases
  • Diosgenin

Grant support

S. Ghosh thanks Council of Scientific and Industrial Research (CSIR, Government of India) for Senior Research Fellowship (09/137(0516)/2012-EMR-I). The authors acknowledge financial support for UPE Phase II- Focus Area Biotechnology, for 2012-2017 by UGC, New Delhi, India. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.