基于肠肝循环关键代谢酶和转运体介导的药物相互作用研究大黄-黄芩药对配伍机制

Enterohepatic circulation is very common in the pharmacokinetic study of traditional Chinese medicines (TCMs). The intuitive changes of double peaks in the plasma concentration-time profile could show the effect of TCMs compatibility on the enterohepatic circulation of ingradients. The metabolic enzyme and transporter are closely involved in te enterohepatic circulation of ingredients within the body. Studies on enzyme- and transporter-based drug-drug interactions will provide evidences for scientific rationale of compatibility of TCMs. Rhei Radix et Rhizoma (DaHuang, DH) and Scutellariae Radix (HuangQin, HQ) are commonly used herb-pairin TCMs. In terms of pharmacokinetic behaviors of typical ingredients, compatibility of these two herbs could result in conspicuous change of he second peaks in the plasma concenration-time profile. In order to explain the reason for this phenomenon, enzyme- and transporter-based drug-rug interactions between DH and HQ during the enterohepatic circulation are studied with in vitro metabolic model, in vivo experiments and transfected cell model. In this project, it is not only i vivo absorption and metabolism of the typical ingredients in DH and HQ which will be studied, but the effects of these ingredients on the activities of the enzyme and transporter. Through these experiments, the potential role of UDP-glucuronosyltransferases, beta-glucuronidase and transporters (MRP2/BCRP) i drug-drug interactions between DH and HQ during the enterohepatic circulation will be illustrated. The experimental data will provide evidence for scientific nationale of compatibility of DH and HQ. And the study of compatibility of DH and HQ as an example could provide the method and new insight to account for the inherent scientific connotation of compatibility mechanism of TCMs.

肠肝循环存在于多种中药组分的体内过程中，药-时曲线上的双峰变化可直观展现中药复方配伍对组分肠肝循环的影响，而基于代谢酶及转运体介导的药物相互作用研究则可能是科学解释上述现象、深入阐明配伍合理性的新途径。本课题以大黄-黄芩药对为研究对象，紧密围绕两药配伍后代表性成分药-时曲线第二吸收峰的显著变化，以肠肝循环关键代谢酶（UGTs、β-葡萄糖醛酸酶）及外排转运体（MRP2、BCRP）介导的组分相互作用为研究主线，采用体外代谢模型、动物在体实验、转染细胞模型等方法，研究两药代表性成分在肠肝循环过程中的代谢处置以及它们对代谢酶及转运体的活性影响，考察相关成分肠肝循环过程中在代谢酶（UGTs、β-葡萄糖醛酸酶）、肠吸收/胆汁分泌外排转运体环节的相互作用，阐明配伍导致两药代表性成分肠肝循环显著变化的内在原因，为大黄黄芩配伍合理性提供科学依据，同时也为从药动学角度深入揭示中药方剂的配伍原理提供方法和思路。

中药复方药效物质基础和配伍规律研究是中医药学的关键科学问题之一，也是制约中医药现代化进程的关键环节。本项目以常用泻火解毒药对大黄-黄芩为研究对象，基于药材配伍的药动学研究结果，深入探讨了组分配伍对特征成分体内过程的影响，从药物代谢酶及转运体的角度对组分配伍的相互作用机制进行了阐释。研究发现经生物合成的大黄素葡萄糖醛酸苷对黄芩苷肠内吸收的关键代谢酶—β-葡萄糖醛酸苷酶的活性具有抑制作用，从而影响了黄芩苷的肠吸收过程。研究发现5种蒽醌类成分中大黄素对黄芩素葡萄糖醛酸化反应的抑制作用最强，大黄素能够竞争性抑制黄芩素在大鼠肝微粒体中的葡萄糖醛酸结合反应，而在人肝微粒体、人肠S9、大鼠肠S9中，大黄素对黄芩素葡萄糖醛酸结合反应表现出混合型抑制的特征；大鼠体内药动学实验结果表明大黄素抑制了大鼠肝脏中UGTs的活性，使得黄芩素在大鼠体内暴露量增加，而经UGTs代谢生成的黄芩苷体内暴露量降低。研究发现联用大黄酸后黄芩苷由肠上皮细胞外排至肠腔的量减少，相应地黄芩苷吸收入血的量增多，这一影响是通过抑制介导黄芩苷外排的转运体BCRP而实现的；联用大黄素后黄芩苷的外排转运量有升高趋势，但无显著性差异，这一结果与阳性对照组（联用丙磺舒）的结果相似，说明大黄素可能竞争性抑制由MRP2介导的黄芩苷的外排作用，但由于BCRP转运体的代偿性作用，使联用大黄素后黄芩苷的累积外排量并没有显著降低。该项研究从代谢酶和转运体角度深入探讨了大黄-黄芩配伍机制，同时也为中药配伍机制的研究提供了新的思路和借鉴。该研究目前已发表论文8篇，其中SCI论文7篇。