Protein tyrosine phosphatase 1B inhibitory by dammaranes from Vietnamese Giao-Co-Lam tea.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE:

Gynostemma pentaphyllum (Thunb.) tea was used in Vietnamese folk medicine as anti-diabetic agent.

AIM OF THE STUDY:

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.

MATERIALS AND 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.

CONCLUSION:

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: Tran Manh Hung, Duc Manh Hoang, Jin Cheol Kim, Han-Su Jang, Jong Seog Ahn, Byung-Sun Min
• Journal: Journal of ethnopharmacology (J Ethnopharmacol) Vol. 124 Issue 2 Pg. 240-5 (Jul 15 2009) ISSN: 1872-7573 [Electronic] Ireland
• PMID: 19397985 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Nitrophenols
• Organophosphorus Compounds
• Plant Extracts
• Triterpenes
• nitrophenylphosphate
• dammarane
• Protein Tyrosine Phosphatase, Non-Receptor Type 1

Topics

• Diabetes Mellitus, Type 2 (drug therapy)
• Dose-Response Relationship, Drug
• Gynostemma (chemistry)
• Humans
• Inhibitory Concentration 50
• Medicine, East Asian Traditional
• Nitrophenols (metabolism)
• Organophosphorus Compounds (metabolism)
• Phytotherapy
• Plant Components, Aerial
• Plant Extracts (chemistry, pharmacology)
• Protein Tyrosine Phosphatase, Non-Receptor Type 1 (antagonists & inhibitors)
• Triterpenes (isolation & purification, pharmacology)