Protein tyrosine phosphatase 1B inhibitory by dammaranes from Vietnamese Giao-Co-Lam tea.
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.
Hung
Tran Manh
TM
College of Pharmacy, Catholic University of Daegu, Gyeongsan 712-702, Republic of Korea.
Hoang
Duc Manh
DM
Kim
Jin Cheol
JC
Jang
Han-Su
HS
Ahn
Jong Seog
JS
Min
Byung-Sun
BS
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
D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010936:Plant Extracts; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D014315:Triterpenes; D000097669:Dammaranes; C008644:nitrophenylphosphate