Abstract
1. The nephrotoxicant N-(3,5-dichlorophenyl)succinimide (NDPS) underwent non-enzymatic hydrolysis to N-(3,5-dichlorophenyl)succinamic acid (NDPSA) in buffer, rat liver and kidney homogenates, and rabbit liver homogenates.
2. In the presence of NADPH, rat liver homogenates converted NDPS to NDPSA and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA).
3. Using liver homogenates from the phenobarbital (PB)-pretreated rat, 2-NDHSA production was increased 5-fold, and the metabolites N-(3,5-dichlorophenyl)-2-hy-droxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-3-hydroxysuccinamic acid (3-NDHSA) were also detected. Formation of these latter metabolites was suppressed by CO or omission of NADPH. No hydroxylated metabolites were detected when NDPSA was incubated with PB-induced rat liver homogenates.
4. Oxidative metabolites were not produced when NDPS was incubated with kidney homogenates from the control or PB-pretreated rat.
5. NDHS underwent rapid hydrolysis in buffer to yield 2-NDHSA and 3-NDHSA.
6. Rabbit liver homogenates converted NDPS to NDPSA, 3,5-dichloroaniline (DCA), and succinic acid (SA). Production of DCA and SA was inhibited by the amidase inhibitor bis-p-nitrophenyl phosphate. Oxidative metabolism did not occur in rabbit tissue.
7. These experiments demonstrate that a PB-inducible form of rat liver P450 converts NDPS to NDHS, which then undergoes hydrolysis to 2-NDHSA and 3-NDHSA. An alternative route of production for 2-NDHSA and 3-NDHSA, via hydroxylation of NDPSA, does not occur. In rabbit liver NDPS metabolism was primarily amidase-mediated.