title: Protein tyrosine phosphatase 1B inhibitory by dammaranes from Vietnamese Giao-Co-Lam tea.
abstract: BACKGROUND
  Gynostemma pentaphyllum (Thunb.) tea was used in Vietnamese folk medicine as anti-diabetic agent.
  
  
  OBJECTIVE
  This study was aimed to investigate the inhibitory activities of fractions and constituents isolated from Gynostemma pentaphyllum on protein tyrosine phosphatase 1B (PTP1B) since it has been proposed as a treatment therapy for type 2 diabetes and obesity.
  
  
  METHODS
  The 70% EtOH extract, CHCl3 fraction, EtOAc fraction, BuOH fraction, and seven isolated dammarane triterpenes were evaluated for their inhibitory activity in protein phosphatase enzymes (PTP1B and VHR).
  
  
  RESULTS
  CHCl3-soluble fraction showed a dose-dependent inhibitory activity of the PTP1B enzyme with the IC50 value of 30.5 microg/mL. Among seven tested compounds, compounds 6 showed the most potent PTP1B inhibitory activity with IC50 value of 5.3+/-0.4 microM compared to a range 15.7-28.5 microM for the other six compounds. The inhibition mode of 6 was competitive toward p-NPP with a K(i) value of 2.8 microM.
  
  
  CONCLUSIONS
  These study results suggested that the PTP1B inhibitory activity of these dammaranes may enable this plant to play an important role in the treatment of diabetes.
authors.affiliation: College of Pharmacy, Catholic University of Daegu, Gyeongsan 712-702, Republic of Korea.
authors.forename: Tran Manh
authors.initials: TM
authors.lastname: Hung
authors.forename: Duc Manh
authors.initials: DM
authors.lastname: Hoang
authors.forename: Jin Cheol
authors.initials: JC
authors.lastname: Kim
authors.forename: Han-Su
authors.initials: HS
authors.lastname: Jang
authors.forename: Jong Seog
authors.initials: JS
authors.lastname: Ahn
authors.forename: Byung-Sun
authors.initials: BS
authors.lastname: Min
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D029774:Gynostemma / Q000737:chemistry*; D006801:Humans; D020128:Inhibitory Concentration 50; D008518:Medicine, East Asian Traditional; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D008517:Phytotherapy; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000037:antagonists & inhibitors*; D014315:Triterpenes / Q000302:isolation & purification / Q000494:pharmacology*; D000097669:Dammaranes
chemical_list: D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010936:Plant Extracts; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D014315:Triterpenes; D000097669:Dammaranes; C008644:nitrophenylphosphate