Oxyresveratrol has the inhibitory activity on tyrosinase.In order to extract this bioactive substance from mulberry branch,ethanol fractionation,silica gel column chromatography and Sephadex LH-20 gel filtration chromatography were employed to isolate and prepare mulberry oxyresvertrol sample.Identification of its chemical structure and molecular weight by nuclear magnetic resonance(NMR),HPLC-MS and other measures verified that the prepared sample was oxyresvertrol.Detection with high performance liquid chromatography showed that its mass fra...