Fig. 5. A. PTP1B in Oleanane hemiacetal glycosides from Gymnema latifolium and their inhibitory effects on protein tyrosine phosphatase 1B

Fig. 5. A. PTP1B inhibitory activities of compounds 1–9. B. Lineweaver-Burk plots for determination of the type of PTP1B inhibition of compounds 2 and 3 using pNPP assay. The conditions were as follows: 4 mM substrate, 0.05–0.1 μg/mL of PTP1B enzyme, 50 mM Tris (pH 7.5), at room temperature. In the presence of different concentrations of compounds for lines from bottom to top: A. Compound 2 (20, 30 and 40 μM); B. Compound 3 (10, 20 and 30 μM). The data were evaluated in three replicates at each substrate concentration.