Flavanones from the stem bark of Erythrina abyssinica

Twelve new flavanones bearing a 2,2-dimethylpyrano ring were isolated from a MeOH extract of the stem bark of Erythrina abyssinica. Their structures were determined on the basis of spectroscopic (UV, CD, 1D and 2D NMR, HRMS) and physico-chemical analyses. Compounds 1, 3, 5, 6, 8, and 9 exhibited inhibitory effects on the enzyme activity of PTP1B in an in vitro assay with IC50 values ranging from 13.9 ± 2.1 to 19.0 ± 1.8 μM. These results suggest that prenyl and methoxy groups on the B ring contribute to the inhibitory activity of flavanones against PTP1B. Crown Copyright © 2008.