Ubeaud G, Schiller C D, Hurbin F, Jaeck D, Coassolo P
F. Hoffmann-La Roche Ltd., Pharma Division, Preclinical Research, Basel, Switzerland.
Eur J Pharm Sci. 1999 Aug;8(4):255-60. doi: 10.1016/s0928-0987(99)00016-0.
The flavin-containing monooxygenase (FMO)-dependent N-oxidation of benzydamine has been assessed as a method for monitoring the activity of FMOs in monolayer cultures of hepatocytes from rat, dog, rabbit, hamster and human. The advantage of this substrate is that benzydamine N-oxide formation can be measured directly in extracts of cellular incubations without an intensive work-up procedure. Benzydamine and its N-oxide are readily separated by HPLC with fluorometric detection. This assay proved sensitive enough to monitor FMOs activity in intact monolayer of cultured hepatocytes. The formation of benzydamine N-oxide was inhibited when hepatocytes were coincubated with methimazole (another FMO substrate) in a dose-dependent manner, whereas N-octylamine (an inhibitor of cytochrome P450) had no inhibitory effect. In contrast to cytochrome P450, FMO activity assessed by benzydamine N-oxidation was relatively stable for all species studied during 72-h cultures.
已评估了含黄素单加氧酶（FMO）依赖的苄达明N-氧化反应，以此作为监测大鼠、犬、兔、仓鼠和人肝细胞单层培养物中FMO活性的一种方法。该底物的优势在于，苄达明N-氧化物的形成可在细胞培养物提取物中直接测定，无需繁琐的后处理程序。苄达明及其N-氧化物可通过高效液相色谱结合荧光检测轻松分离。该测定方法被证明灵敏度足以监测培养肝细胞完整单层中的FMO活性。当肝细胞与甲巯咪唑（另一种FMO底物）共同孵育时，苄达明N-氧化物的形成呈剂量依赖性受到抑制，而N-辛胺（细胞色素P450的抑制剂）则无抑制作用。与细胞色素P450不同，在72小时培养期间，通过苄达明N-氧化评估的FMO活性在所有研究物种中相对稳定。
