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

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• 作者：Tran Manh Hung ; Duc Manh Hoang ; Jin Cheol Kim ; Han-Su Jang ; Jong Seog Ahn ; Byung-Sun Min
• 关键词：Gynostemma pentaphyllum ; Cucurbitaceae ; Dammarane ; Triterpene ; Protein tyrosine phosphatase 1B activity
• 刊名：Journal of Ethnopharmacology
• 出版年：2009
• 出版时间：15 July 2009
• 年：2009
• 卷：124
• 期：2
• 页码：240-245
• 全文大小：456 K

文摘

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 μg/mL. Among seven tested compounds, compounds 6 showed the most potent PTP1B inhibitory activity with IC₅₀ value of 5.3 ± 0.4 μM compared to a range 15.7–28.5 μM for the other six compounds. The inhibition mode of 6 was competitive toward p-NPP with a K_i value of 2.8 μM.

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.