Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.
J Ethnopharmacol. 2013 Jan 30;145(2):670-5. doi: 10.1016/j.jep.2012.11.038. Epub 2012 Dec 5.
Ginkgo biloba, which is one of the most frequently used herbal medicines, is commonly used in the management of several conditions, including memory impairment. Previously, it was reported to decrease the expression of peripheral benzodiazepine receptor and the biosynthesis of glucocorticoids, thereby regulating glucocorticoid levels. However, it is not known whether Ginkgo biloba extract regulates the function of the glucocorticoid receptor.
We determined whether Ginkgo biloba extract and several of its chemical constituents affect the activity of human glucocorticoid receptor (hGR).
A hGR-dependent reporter gene assay was conducted in HepG2 human hepatocellular carcinoma cells and hGR target gene expression assays were performed in primary cultures of human hepatocytes.
Multiple lots and concentrations of the extract and several of its chemical constituents (ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, and bilobalide) did not increase hGR activity, as assessed by a cell-based luciferase reporter gene assay. The extract did not influence the expression of hGR target genes, including tyrosine aminotransferase (hTAT), constitutive androstane receptor (hCAR), or pregnane X receptor (hPXR), in primary cultures of human hepatocytes. Moreover, hGR antagonism by mifepristone (also known as RU486) did not attenuate the extent of induction of hCAR- and hPXR-regulated target genes CYP2B6 and CYP3A4 by Ginkgo biloba extract.
Ginkgo biloba extract, ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, and bilobalide are not activators of hGR. Furthermore, the extract does not influence the hGR-hCAR or the hGR-hPXR signaling pathway in primary cultures of human hepatocytes.
银杏，一种最常被使用的草药，常用于治疗多种疾病，包括记忆损伤。先前，它被报道能降低外周苯二氮䓬受体和糖皮质激素的生物合成，从而调节糖皮质激素水平。然而，银杏提取物是否调节糖皮质激素受体的功能尚不清楚。
我们确定银杏提取物及其几种化学成分是否影响人糖皮质激素受体（hGR）的功能。
在 HepG2 人肝癌细胞中进行 hGR 依赖性报告基因检测，并在人原代肝细胞中进行 hGR 靶基因表达检测。
多种批次和浓度的提取物及其几种化学成分（银杏内酯 A、银杏内酯 B、银杏内酯 C、银杏内酯 J 和白果内酯）均未通过基于细胞的荧光素酶报告基因检测增加 hGR 活性。提取物未影响 hGR 靶基因的表达，包括人酪氨酸转氨酶（hTAT）、组成型雄烷受体（hCAR）或孕烷 X 受体（hPXR）在人原代肝细胞中的表达。此外，米非司酮（也称为 RU486）的 hGR 拮抗作用并未减弱银杏提取物诱导 hCAR 和 hPXR 调节的靶基因 CYP2B6 和 CYP3A4 的程度。
银杏提取物、银杏内酯 A、银杏内酯 B、银杏内酯 C、银杏内酯 J 和白果内酯不是 hGR 的激活剂。此外，提取物不会影响人原代肝细胞中的 hGR-hCAR 或 hGR-hPXR 信号通路。
