New 5-deoxyflavonoids and their inhibitory effects on protein tyrosine phosphatase 1B (PTP1B) activity

In the course of our program to search for protein tyrosine phosphatase 1B (PTPB) inhibitors, five new 5-deoxyflavonoids along with eight known derivatives were isolated from EtOAc layer of the root bark of Erythrina abyssinica. Their structures were elucidated on the basis of spectroscopic (IR, UV, MS, CD, 1D- and 2D-NMR) and physicochemical analyses. All isolates exhibited moderate inhibitory effects on the enzyme assay with IC50 values ranging from 14.9 ± 1.6 to 98.1 ± 11.3 μM. Compounds with prenyl and methoxy groups in the B ring (1, 2, 4, 8, and 13) possessed strong activity (IC50 14.9 ± 1.6 to 19.2 ± 1.1 μM), while compounds (3, 5, and 9) with 2,2-dimethylpyrano ring showed less inhibitory effect (IC50 22.6 ± 2.3 to 72.9 ± 9.7 μM). These results suggest that prenyl and methoxy groups may be responsible for the increase on the activity of 5-deoxyflavonoids against PTP1B, but the presence of 2,2-dimethylpyrano ring on the B ring may be induced the decrease of PTP1B inhibitory activity.

Five new 5-deoxyflavonoids along with eight known analogues were isolated from an EtOAc-soluble extract of the root bark of Erythrina abyssinica. All compounds showed dose-dependant inhibitory effects on the enzyme activity of protein tyrosine phosphatase 1B (PTP1B) in an in vitro assay with IC50 values ranging from 14.9 ± 1.6 to 72.9 ± 9.7 μM. Compounds with prenyl and methoxy groups on the B ring possessed higher activity than those bearing the 2,2-dimethylpyrano ring in the structure.Figure optionsDownload as PowerPoint slide