通过溶剂提取、皂化、分子蒸馏以及色谱分离等方法得到了7组银杏叶类脂重馏分不同极性馏分以及聚戊烯醇，用4种抗氧化测定方法（ DPPH、ABTS、超氧阴离子和羟自由基法），结合Sigmoidal拟合曲线法求银杏叶类脂重馏分不同极性馏分以及聚戊烯醇的IC50，以评价银杏叶类脂重馏分以及聚戊烯醇的抗氧化作用。结果显示，在超氧阴离子和羟自由基测定法中，银杏叶聚戊烯醇的IC50均低于阳性对照组及其他各馏分组。除阳性对照组（Vc和BHT）以及聚戊烯醇组之外，馏分5（V（石油醚）∶V（乙酸乙酯）＝60∶40部位）的抗氧化作用最强。所有馏分样品中偏离最大的实际清除率与理论清除率为0．5的相对偏差为1．8％，说明Sigmoidal拟合曲线法求银杏叶类脂重馏分不同极性馏分以及聚戊烯醇的IC50是合理的。%Seven fractions and polyprenols separated from heavy distillates of ginkgo lipids were prepared by extraction with pe-troleum ether, saponification, molecular distillation and chromatographic isolation.Four methods (DPPH, ABTS, super-oxide anion and hydroxy radical) with Sigmoidal curve fitting method arriving at respective IC50 values was used to deter-mine the antioxidant effect of the seven fractions and polyprenols .IC50 values of the polyprenols group are lower than those of all the fractions groups and the positive control groups (Vc and BHT) by superoxide anion and hydroxy radical methods. The fraction 5 (60%petroleum ether/40%acetic ether) has the highest antioxidant effect in all tested fractions except the positive control groups and the polyprenols group by four methods .The relative deviation between theoretical clearance rate (0.5) and actual clearance rate of the fraction with aximum deviation in all fractions is 1.8%.Therefore, IC50 values of different polar fractions of heavy distillates and polyprenols separated from ginkgo lipids can be generated with Sigmoidal curve fitting method.
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