代谢
[14C]异芬磷(IFP)在大鼠、豚鼠、猴子、狗和人肝脏微粒体P450酶的作用下转化为异芬磷氧(IFP-oxon)、N-脱异芬磷(d-N-IFP)和N-脱异芬磷氧(d-N-IFP-oxon)的代谢速率得到了研究,以获得米氏动力学(Michaelis-Menten)的Vmax和Km值。猴子将IFP转化为IFP-oxon(脱硫)的Vmax值最高,为每1.3纳摩尔P450 162纳米摩尔异芬磷/小时,其次是豚鼠(98)、大鼠(66)、狗(43)和人(14)。对于异芬磷脱硫的Km值,分别为猴子19.2、豚鼠7.4、大鼠14.1、狗23.3和人18.4微摩尔。对于脱烷基过程(将IFP转化为d-N-IFP),猴子的Vmax值为每1.3纳摩尔P450 64.6纳米摩尔异芬磷/小时,大鼠为17.2,狗为9.7,人为7.3。在脱烷基过程中,猴子具有最高的Km值,为16.3微摩尔IFP,其次是人(11.2)、大鼠(9.9)和狗(9.3)。IFP-oxon和d-N-IFP转化为d-N-IFP-oxon的代谢速率分别进行了研究。本研究获得的动物和人类肝脏P450酶的Vmax和Km值将用于开发PB-PK/PB-PD模型,以预测异芬磷在动物和人体中的命运和毒性。
The rate of metabolism of [14C]isofenphos (IFP) to isofenphos oxon (IFP-oxon), des N-isofenphos (d-N-IFP), and des N-isofenphos oxon (d-N-IFP-oxon) by rat, guinea pig, monkey, dog, and human liver microsomal p450 enzymes was studied to obtain Vmax and Km values for Michaelis-Menten kinetics. The monkey had the highest Vmax value for the conversion of IFP to IFP-oxon (desulfuration), 162 nmol isofenphos hr-1 per 1.3 nanomoles p450, followed by guinea pig (98), rat (66), dog (43), and human (14). The Km values for the desulfuration of isofenphos were 19.2, 7.4, 14.1, 23.3, and 18.4 microM, respectively, for the monkey, guinea pig, rat, dog, and human. The Vmax values for the dealkylation process (conversion of IFP to d-N-IFP) were 64.6, 17.2, 9.7, and 7.3 nmol isofenphos hr-1 per 1.3 nanomoles P-450 for the monkey, rat, dog, and human, respectively. For the dealkylation process, monkey had the highest Km value, 16.3 microM IFP, followed by human (11.2), rat (9.9), and dog (9.3). The rate of metabolism of IFP-oxon and d-N-IFP to d-N-IFP-oxon were separately studied. The Vmax and Km values obtained in this study for animal and human liver p450 enzymes will be used to develop a PB-PK/PB-PD model to predict the fate and toxicity of isofenphos in animals and man.
来源:Hazardous Substances Data Bank (HSDB)