不同天数银杏叶发酵液提取物的体外抗氧化活性比较

目的： 考察银杏叶培养基经过冠突散囊菌发酵不同时间后乙酸乙酯提取物的体外抗氧化活性。 方法： 将冠突散囊菌接种于银杏叶培养基中分别发酵4，7，11，14 d后，真空抽滤得到滤液，利用溶剂分级萃取得到提取液，以未发酵银杏叶乙 酸乙酯提取液作为对照。结合酶标仪，通过清除DPPH（1，1-二苯基-2-三硝基苯肼）自由基、ABTS 自由基，以及铁还原能力，比较不同发酵天数乙酸乙酯提取物的抗氧化能力。 结果： 测定了不同天数银杏叶发酵液乙酸乙酯提取物的抗氧化活性，发现11 d发酵液提取物抗氧化活性最强，DPPH半数抑制浓度（IC₅₀）105.60 mg·L^-1，ABTS IC₅₀ 102.09 mg·L^-1更接近维生素C（VC）的IC₅₀值，同时，11 d组铁还原实验的吸光度在不同浓度梯度下均为最大值。 结论： 初步确定银杏叶培养基发酵11 d后，发酵液中的抗氧化活性成分积累量最大。

Comparison of Anti-oxidation of Ethyl Acetate Extracts from Ginkgo biloba Leaves Medium Under Different Fermentation Time Condition in vitro

Objective: To compare antioxidative activity of Ginkgo biloba fermentation liquid ethyl acetate extract under different fermentation time. Method: The Eurotium cristatum was inoculated into liquid medium, incubation time were 4,7,11,14 d respectively. The ethyl acetate extract of G. biloba aqueous extract was treated as control. E. cristatum and some residual impurities were filtrated to harvest clear fermentation liquor, and extracted by solvent extractions. Antioxidation of ethyl acetate extract was evaluated by 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS) and ferric reducing antioxidant power (FRAP) assays. The different activitiesfrom fermentation time were compared. Result: All above extracts showed different antioxidant activities, moreover, 11 d extracts displayed the best activity:DPPH 50% inhibiting concentration(IC₅₀) 105.7 mg·L^-1;ABTS IC₅₀ 83.6 mg·L^-1, which was close to vitamine C(VC) and the results of absorbance in FRAP test were quite consistent. Conclusion: Antioxidative composition accumulated in G.biloba fermentation liquor was largest at 11 d fermentation time.