Steinke B, Müller B, Wagner H
Institut für Pharmazeutische Biologie, Universität München, Federal Republic of Germany.
Planta Med. 1993 Apr;59(2):155-60. doi: 10.1055/s-2006-959633.
The determination of the inhibition of PAF (platelet-activating factor)-induced platelet aggregation has been proposed as a biological standardization method for commercially available Ginkgo biloba extracts by measuring the characteristic pharmacological effect of ginkgolides in vitro. The determination is specific for ginkgolides A, B, C, and J and is not influenced by other constituents present in Ginkgo biloba extracts. IC50 values of ginkgolide B can be used to standardize various Ginkgo extracts produced by special extraction methods with respect to equi-effective ginkgolide B contents. In order to compare values obtained by a chemical-analytical procedure with those obtained by the biological assay, the equi-effective total ginkgolide content of each Ginkgo extract had to be calculated. Accordingly, the concentrations of the individual ginkgolides in the various Ginkgo extracts were determined chromatographically by assaying ginkgolides as trime-thylsilyl derivatives. Their individual contributions towards the measured in vitro effects were derived from their respective IC50 values. The calculated equi-effective total ginkgolide contents of the Ginkgo extracts were in good agreement with those obtained by gas chromatography. The results demonstrate that, in addition to a chemical standardization, the biological standardization of Ginkgo extract preparations is also feasible.
通过体外测量银杏内酯的特征药理作用，已提出将测定血小板活化因子（PAF）诱导的血小板聚集抑制作用作为市售银杏叶提取物的一种生物标准化方法。该测定对银杏内酯A、B、C和J具有特异性，不受银杏叶提取物中其他成分的影响。银杏内酯B的半数抑制浓度（IC50）值可用于标准化通过特殊提取方法生产的各种银杏提取物中具有等效银杏内酯B含量的情况。为了将化学分析程序获得的值与生物测定获得的值进行比较，必须计算每种银杏提取物的等效总银杏内酯含量。因此，通过将银杏内酯作为三甲基硅烷基衍生物进行测定，用色谱法测定了各种银杏提取物中各个银杏内酯的浓度。它们对体外测量效应的各自贡献来自其各自的IC50值。计算得到的银杏提取物等效总银杏内酯含量与气相色谱法得到的结果吻合良好。结果表明，除了化学标准化外，银杏提取物制剂的生物标准化也是可行的。
