We developed a nanoreactor chip based system to mimic phase I metabolic reactions of small organic compounds. The microchip, made of silicon, has an anatase-phase titanium dioxide (TiO2) nanolayer coating for photocatalysis and an integrated electrospray ionization (ESI) tip for direct mass spectrometric (MS) analysis. This novel method for mimicking phase I metabolic reactions uses an on-chip TiO2-nanolayer and an external UV-lamp to induce photocatalyzed chemical reactions of drug compounds in aqueous solutions. The reactions of selected test compounds (verapamil, metoprolol, propranolol, lidocaine, 2-acetamidofluorene, and S-methylthiopurine) produced mostly the same main products as phase I metabolic reactions induced by human liver microsomes, rat hepatocytes, or cytochrome P enzymes, showing hydroxylation, dehydrogenation, and dealkylations as the main photocatalytic reactions. With this method it is possible to detect reactive and toxic products (mimicking reactive metabolites) due to the absence of biological matrices and an immediate analysis. The method used is sensitive: only 20–40 pmol (1–10 ng) of a substrate was needed for the experiment, thus it provides an inexpensive method for screening possible metabolites of new drug candidates. Due to small dimensions of the microchip, diffusion lengths are suitable for the high reaction rates, thus providing a rapid analysis as the reaction products can be detected and identified directly after the photoinduced reactions have occurred. The method shows a similar performance to that of electrochemistry, a commonly used technique for mimicking phase I metabolism.
我们开发了一种基于纳米反应器芯片的系统,用于模拟小型有机化合物的第一阶段代谢反应。这种微芯片由
硅制成,具有
锐钛矿相
二氧化钛(TiO2)纳米层涂层,用于光催化;集成电喷雾离子化(ESI)尖端,用于直接质谱(MS)分析。这种模拟第一阶段代谢反应的新方法使用片上
二氧化钛纳米层和外部紫外灯来诱导
水溶液中药物化合物的光催化
化学反应。选定测试化合物(
维拉帕米、
美托洛尔、
普萘洛尔、
利多卡因、2-乙酰
氨基
芴和 S-甲基
硫嘌呤)的反应产生的主要产物与人肝微粒体、大鼠肝细胞或细胞色素 P 酶诱导的 I 期代谢反应基本相同,显示羟化、脱氢和脱烷基是主要的光催化反应。由于不需要
生物基质和即时分析,这种方法可以检测反应性和毒性产物(模拟反应性代谢物)。该方法灵敏度高:实验只需 20-40 pmol(1-10 ng)的底物,因此是筛选新药候选物可能代谢物的廉价方法。由于微芯片尺寸小,扩散长度适合高反应速率,因此可以在光诱导反应发生后直接检测和鉴定反应产物,从而提供快速分析。该方法的性能与模拟第一阶段新陈代谢的常用技术--电
化学类似。