Activation of AMP-activated protein kinase by a plant-derived dihydroisosteviol in human intestinal epithelial cell

Biol Pharm Bull. 2013;36(4):522-8. doi: 10.1248/bpb.b12-00711. Epub 2013 Jan 24.


Our previous study has shown that dihydroisosteviol (DHIS), a derivative of stevioside isolated from Stevia rebaudiana (Bertoni), inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated transepithelial chloride secretion across monolayers of human intestinal epithelial (T84) cells and prevents cholera toxin-induced intestinal fluid secretion in mouse closed loop models. In this study, we aimed to investigate a mechanism by which DHIS inhibits CFTR activity. Apical chloride current measurements in Fisher rat thyroid cells stably transfected with wild-type human CFTR (FRT-CFTR cells) and T84 cells were used to investigate mechanism of CFTR inhibition by DHIS. In addition, effect of DHIS on AMP-activated protein kinase (AMPK) activation was investigated using Western blot analysis. Surprisingly, it was found that DHIS failed to inhibit CFTR-mediated apical chloride current in FRT-CFTR cells. In contrast, DHIS effectively inhibited CFTR-mediated apical chloride current induced by a cell permeable cAMP analog CPT-cAMP and a direct CFTR activator genistein in T84 cell monolayers. Interestingly, this inhibitory effect of DHIS on CFTR was significantly (p<0.05) reduced by pretreatment with compound C, an AMPK inhibitor. AICAR, a known AMPK activator, was able to inhibit CFTR activity in both FRT-CFTR and T84 cells. Western blot analysis showed that DHIS induced AMPK activation in T84 cells, but not in FRT-CFTR cells. Our results indicate that DHIS inhibits CFTR-mediated chloride secretion in T84 cells, in part, by activation of AMPK activity. DHIS therefore represents a novel candidate of AMPK activators.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism*
  • Animals
  • Cell Line
  • Chlorides / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / antagonists & inhibitors*
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • Diterpenes, Kaurane / pharmacology*
  • Enzyme Activators / pharmacology*
  • Epithelial Cells / drug effects*
  • Epithelial Cells / metabolism
  • Humans
  • Intestinal Mucosa / cytology
  • Rats
  • Stevia


  • CFTR protein, human
  • CFTR protein, rat
  • Chlorides
  • Diterpenes, Kaurane
  • Enzyme Activators
  • dihydroisosteviol
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • AMP-Activated Protein Kinases