Study on extract process and antioxidant activities of polyphenol from the Ginkgo biloba exocarp

Ginkgo biloba exocarp being material and ethanol being solution to extract phenolic compounds, the ethanol extraction conditions and oxidation resistance of crude extract from the ginkgo biloba exocarp (PEGB) were studied. Taking ethanol volume fraction, extracting time and temperature as well as ratio of solid to liquid to conduct single factor experiment, the extraction conditions were further optimized with response surface methodology. The results showed that the optimal extraction conditions were as follows:ethanol concentration70%, extracting time 2.6h, temperature 90℃ and ratio of solid to liquid 1∶30. The extracting rate of crude extract was 5.33 mg GAE/g under such conditions. The scavenging effect of PEGB crude extract on DPPH and hydroxyl radicals was enhanced with increased concentration. When the concentration of PEGB crude extract was 0.5mg/mL, the clearance rate for DPPH was 84.25% and 78.89% for hydroxyl radicals. It showed that high concentrations of PEGB crude extract had strong antioxidant properties.