Spectroscopic studies of inhibitory effect on tyrosinase of prunella vulgaris L.flavonoids

The inhibitory effect on tyrosinase and its inhibitory mechanism of Prunella vulgaris L.flavonoid as investigated by UV-vis absorption,fluorescence and circular dichroism(CD) spectroscopy.The result indicated that the Prunella vulgaris L.flavonoids was a reversible and competitive inhibitor,and the flavonoids could inhibit the activity of tyrosinase rapidly.The half inhibition concentration(IC50) of the flavonoids and inhibition constant(Ki) were obtained to be 79.25 μg/mL and 130.33 μg/mL,respectively.The fluorescence spectra showed that the Prunella vulgaris L.flavonoids increased significantly the hydrophobicity of tyrosinase.The analysis of CD spectra indicated that the binding of the flavonoids to tyrosinase could induce conformational partial change in tyrosinase.