Zhang D, Evans F E, Freeman J P, Duhart B, Cerniglia C E
National Center for Toxicological Research, U.S. Food and Drug Administration.
Drug Metab Dispos. 1995 Dec;23(12):1417-25.
A fungal biotransformation system as an in vitro model for mammalian drug metabolism was investigated. Amitriptyline, a widely used antidepressant, was effectively biotransformed within 72 hr by the filamentous fungus, Cunninghamella elegans. Eight major metabolites in HPLC elution order (11-hydroxyamitriptyline N-oxide, 11-hydroxynortriptyline, 11-hydroxyamitriptyline, 10-hydroxyamitriptyline, 3-hydroxyamitriptyline, 2-hydroxyamitriptyline, nortriptyline, and amitriptyline N-oxide) were produced at estimated molar ratios of 2:1:10:0.6:0.1:1.2.5:0.5, respectively. These metabolites were isolated by HPLC and identified by UV/MS analyses, as well as NMR spectroscopic analysis for most of these metabolites. In some cases, they were also compared with authentic standards. Glucose, culture age, and substrate concentration significantly affected the extent of amitriptyline metabolism. Kinetic studies indicated that nortriptyline and 11-hydroxyamitriptyline were produced as initial major metabolites. The hydroxylated metabolite was excreted from mycelia, but amitriptyline and its N-demethylated metabolite, nortriptyline, were not. An 18O2 labeling experiment showed that the oxygen atoms in 11-hydroxyamitriptyline and 2-hydroxyamitriptyline were derived from molecular oxygen. The cytochrome P450 inhibitors SKF 525-A (1.5 mM), metyrapone (2.0 mM), and 1-aminobenzotriazole (1.0 mM) inhibited the biotransformations of amitriptyline by 50, 75, and 95%, respectively. A microsomal preparation was shown to catalyze the 11-hydroxylation of amitriptyline, which was inhibited by SKF 525-A and carbon monoxide. The similarities of amitriptyline metabolism in C. elegans and in humans and rats are discussed.
研究了一种作为哺乳动物药物代谢体外模型的真菌生物转化系统。阿米替林是一种广泛使用的抗抑郁药，在72小时内被丝状真菌雅致小克银汉霉有效地进行了生物转化。按高效液相色谱洗脱顺序排列的8种主要代谢产物（11-羟基阿米替林N-氧化物、11-羟基去甲替林、11-羟基阿米替林、10-羟基阿米替林、3-羟基阿米替林、2-羟基阿米替林、去甲替林和阿米替林N-氧化物）的生成摩尔比估计分别为2:1:10:0.6:0.1:1.2.5:0.5。这些代谢产物通过高效液相色谱分离，并通过紫外/质谱分析以及对大多数这些代谢产物的核磁共振光谱分析进行鉴定。在某些情况下，还将它们与标准品进行了比较。葡萄糖、培养时间和底物浓度显著影响阿米替林的代谢程度。动力学研究表明，去甲替林和11-羟基阿米替林是最初产生的主要代谢产物。羟基化代谢产物从菌丝体中排出，但阿米替林及其N-去甲基化代谢产物去甲替林则没有。一项18O2标记实验表明，11-羟基阿米替林和2-羟基阿米替林中的氧原子来自分子氧。细胞色素P450抑制剂SKF 525-A（1.5 mM）、甲吡酮（2.0 mM）和1-氨基苯并三唑（1.0 mM）分别抑制阿米替林生物转化50%、75%和95%。微粒体制剂显示可催化阿米替林的11-羟基化反应，该反应受到SKF 525-A和一氧化碳的抑制。文中讨论了雅致小克银汉霉中阿米替林代谢与人和大鼠中代谢的相似性。
