Inhibition of Intestinal and Hepatic Glucuronidation of Mycophenolic Acid by Ginkgo biloba Extract and Flavonoids
作者:Mohamed-Eslam F. Mohamed、Reginald F. Frye
DOI:10.1124/dmd.109.030080
日期:2010.2
Herb-drug interactions have received more attention in recent years because of the widespread popularity of herbal supplements. However, there are limited data on the effect of herbs on glucuronidation in humans. The goal of this work was to examine the effect of Ginkgo biloba extract and its main flavonoid and terpene lactone constituents on mycophenolic acid (MPA) 7- O -glucuronidation. Human liver (HLM) and intestinal (HIM) microsomes were incubated with MPA and G. biloba extract (unhydrolyzed or acid-hydrolyzed), quercetin, kaempferol, ginkgolide A, ginkgolide B, or bilobalide. MPA-7- O -glucuronide formation was inhibited in HLM and HIM incubations by unhydrolyzed [IC50 = 84.3 (HLM) and 6.9 (HIM) μg/ml] and hydrolyzed [IC50 = 20.9 (HLM) and 4.3 (HIM) μg/ml] G. biloba extracts, quercetin [IC50 = 19.1 (HLM) and 5.8 (HIM) μM], and kaempferol [IC50 = 23.1 (HLM) and 7.7 (HIM) μM]. Terpene lactones did not show inhibition of MPA glucuronidation. Quercetin was a mixed-type inhibitor in HLM and HIM incubations [ K i = 11.3 (HLM) and 2.8 (HLM) μM], whereas kaempferol was a noncompetitive inhibitor in HLM ( K i = 33.7 μM) and a mixed-type inhibitor in HIM ( K i = 4.5 μM). These results indicate that G. biloba extract or quercetin- and kaempferol-rich supplements may inhibit intestinal and hepatic glucuronidation of MPA. Future studies are needed to evaluate the clinical significance of this interaction.
近年来,由于草药补充剂的广泛流行,草药与药物之间的相互作用受到越来越多的关注。然而,有关草药对人体葡萄糖醛酸化作用的数据却很有限。这项研究的目的是考察银杏叶提取物及其主要黄酮和萜内酯成分对霉酚酸(MPA)7- O-葡萄糖醛酸化的影响。将人肝脏(HLM)和肠道(HIM)微粒体与 MPA 和银杏叶提取物(未水解或酸水解)、槲皮素、山柰醇、银杏内酯 A、银杏内酯 B 或双叶皂苷进行培养。在 HLM 和 HIM 培养液中,未水解[IC50 = 84.3(HLM)和 6.9(HIM)μg/ml]和水解[IC50 = 20.9 (HLM) and 4.3 (HIM) μg/ml] G. biloba extracts, quercetin [IC50 = 19.1 (HLM) and 5.8 (HIM) μM], and kaempferol [IC50 = 23.1 (HLM) and 7.7 (HIM) μM]。萜内酯对 MPA 葡萄糖醛酸化没有抑制作用。槲皮素在 HLM 和 HIM 培养液中是一种混合型抑制剂[K i = 11.3(HLM)和 2.8(HLM)μM],而山奈酚在 HLM 中是一种非竞争性抑制剂(K i = 33.7 μM),在 HIM 中是一种混合型抑制剂(K i = 4.5 μM)。这些结果表明,双叶苦参提取物或富含槲皮素和山奈酚的补充剂可能会抑制 MPA 的肠道和肝脏葡萄糖醛酸化。未来的研究需要评估这种相互作用的临床意义。