Inhibition of VHR dual-specificity protein tyrosine phosphatase activity by flavonoids isolated from Scutellaria baicalensis: structure-activity relationships

Abstract

Three flavonoids: norwogonin, dihydronorwogonin and baicalein, were isolated from the roots of Scutellaria baicalensis, as potential inhibitors of VHR dual-specificity protein tyrosine phosphatase (DS-PTPase). Norwogonin (IC50 = 1.1μM), dihydronorwogonin (IC50 = 2.9μM) and baicalein (IC50 = 2.4μM) showed potent inhibitory activity toward VHR, but had no inhibitory activity against T-cell protein tyrosine phosphatase or serine/threonine protein phosphatase 1. From comparisons to the inhibitory activities of other similar flavonoids, it could be suggested that the presence of a hydroxy group in the B ring of flavonoids interferes with the inhibitory activity toward VHR DS-PTPase.