In vitro metabolism of the nephrotoxicant N-(3,5-dichlorophenyl)succinimide in the Fischer 344 rat and New Zealand white rabbit

Degradation of dimethachlon by a newly isolated bacterium Paenarthrobacter sp. strain JH-1 relieves its toxicity against Chlorella ellipsoidea

Dimethachlon, a broad-spectrum dicarboximide fungicide, poses a hazard to the safety of human and ecosystem due to its residue in the environment. A high-efficient dimethachlon degrading bacteria JH-1 belonging to Paenarthrobacter sp. was isolated and characterized. Strain JH-1 can utilize high concentration of dimethachlon as sole carbon source for growth and degrade 98.53% of 300 mg·L^-1 dimethachlon within 72 h. Crude enzyme of strain JH-1 could degrade 99.76% of 100 mg·L^-1 dimethachlon within 2 h. The optimum degradation condition of dimethachlon by strain JH-1 was at 35 °C and pH 7.0. Dimethachlon was degraded in Paenarthrobacter sp. JH-1 as following: it was firstly converted to 4-(3,5-dichloroanilino)-4-oxobutanoic acid and then subjected to the hydrolysis to 3,5-dichloroaniline and succinic acid, the latter was further degraded. Dimethachlon inhibited the growth of Chlorella ellipsoidea, while Paenarthrobacter sp. JH-1 could degrade dimethachlon to relieve its toxicity. This work facilitates our knowledge of the degradation mechanism of dimethachlon and offers potential resource of microbial strains for the bioremediation of dimethachlon-contaminated environments in the future.

Removal of dimethachlon from soils using immobilized cells and enzymes of a novel potential degrader Providencia stuartii JD

The first potential degrader capable of detoxifying dimethachlon (NDPS) was isolated and identified as Providencia stuartii JD, whose free cells and freely crude enzymes degraded more than 80% and 90% of 50 mg L^-1 NDPS in liquid culture within 7 d and 2 h, respectively. Strain JD metabolized NDPS through the typical pathway, in which NDPS was firstly transformed into succinic acid and 3, 5-dichloroanilin, and the latter was then converted to phenol, which was subsequently degraded to muconic acid further subjected to the mineralization. The immobilization obviously improved the stability and adaptability of cells and enzymes. In laboratory non-sterile soils treated by free or immobilized cells and enzymes, 50 mg kg^-1 NDPS decreased to 15.66 and 13.32 mg kg^-1, or 8.32 and 2.18 mg kg^-1 within 7 d, respectively. In field, immobilized cells and enzymes exhibited significantly higher efficiencies in removing 20.250 kg a.i. ha^-1 NDPS wettable powder from soils after 9 d (96.02% and 98.56%) than free cells and enzymes (79.35% and 66.45%). This study highlights that strain JD promises the great potential to remove hazardous NDPS residues and its immobilized cells and enzymes possess the more promising advantages in the bioremediation of NDPS-contaminated soils in situ.

Involvement of cytochrome P450 in cisplatin treatment: implications for toxicity

PURPOSE

The aim of this study is to evaluate the relationship between the CYP450 enzyme family and cisplatin toxicity.

METHODS

This article examined a collection of studies suggesting that CYP450 enzymes may influence cisplatin toxicity. We performed a narrative mini-review.

RESULTS

The studies review showed that CYP450 enzymes have an important role in drug-induced hepatotoxicity and nephrotoxicity, mainly CYP2E1 and CYP4A11. The studies also suggested that the cisplatin and CYP2E1 interaction leads to the generation of reactive oxygen species (ROS) and other oxidants resulting in renal injury; and that ROS generated by both the use of cisplatin and by the CYP2E1 increases tissue damage, induces apoptosis, and causes liver failure.

CONCLUSIONS

We observed that there is an important relationship between CYP450 and cisplatin, involving increased toxicity. However, the possible mechanisms described for the involvement of CYP450 enzymes in nephrotoxicity and hepatotoxicity induced by cisplatin need to be confirmed by further studies. Therefore, there is a need for a deeper investigation focusing on cisplatin toxicity mediated by CYP450 enzymes, which would undoubtedly contribute to a better understanding of the mechanisms that have been implicated so far.

Renal damage, metabolism and covalent binding following administration of the nephrotoxicant N-(3,5-dichlorophenyl)succinimide (NDPS) to male Fischer 344 rats

In vivo metabolism, nephrotoxicity and covalent binding to proteins were evaluated in male Fischer 344 rats that received [2,3-14C]-N-(3,5-dichlorophenyl)succinimide (14C-NDPS). Some animals were pretreated with the enzyme inducer phenobarbital (PB, 80 mg/kg per day, for 3 days, i.p. in saline) prior to receiving a non-nephrotoxic dose of 14C-NDPS (0.2 mmol/kg, i.p. in corn oil). Other rats were pretreated with the cytochrome P450 inhibitor 1-aminobenzotriazole (ABT, 100 mg/kg, 1 h prior to NDPS, i.p. in saline) before administration of a non-toxic or a toxic dose (0.2 or 0.6 mmol/kg, respectively, i.p. in corn oil) of 14C-NDPS. Non-pretreated animals received either dose of 14C-NDPS, but did not receive PB or ABT. All rats were sacrificed 6 h after administration of 14C-NDPS. Nephrotoxicity was monitored by measuring urine volume, urine protein concentrations, blood urea nitrogen levels, and kidney weights. The NDPS metabolic profile in tissue, blood, and urine was analyzed by HPLC. Covalent binding of 14C-NDPS-derived radioactivity to tissue proteins was also measured. Compared with non-pretreated rats, PB-pretreatment potentiated the toxicity of the non-toxic dose of 14C-NDPS. In contrast, ABT-pretreatment protected the rats against NDPS nephrotoxicity. The amount of N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA), an oxidative, nephrotoxic metabolite of NDPS, was elevated in kidney homogenates and urine by PB-pretreatment (0.2 mmol/mg NDPS). ABT pretreatment inhibited NDPS metabolism at both doses. Covalent binding of 14C-NDPS (0.2 mmol/kg)-derived radioactivity to renal and plasma proteins was higher in the PB-pretreated rats than in the non-pretreated animals. In contrast, ABT-pretreatment partially inhibited covalent binding at both doses of 14C-NDPS. Our results suggest that there is a relationship between oxidative metabolism of NDPS, covalent binding of an NDPS metabolite to renal proteins, and NDPS-induced nephrotoxicity in rats.

Determination of the site of glucuronidation in an N-(3,5-dichlorophenyl)succinimide metabolite by electrospray ionization tandem mass spectrometry following derivatization to picolinyl esters

Derivatization using 3-pyridylcarbinol coupled with liquid chromatography electrospray ionization tandem mass spectrometry (LC/MS/MS) was used to characterize a novel Phase II metabolite of the nephrotoxic agricultural fungicide, N-(3,5-dichlorophenyl)succinimide (NDPS). A glucuronide conjugate of N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA) was identified in the urine from a rat dosed with [14C]NDPS. However, 2-NDHSA contains an aliphatic hydroxyl group and a carboxylic acid group, both of which are potential sites for glucuronidation. Mass spectrometry alone was unable to distinguish between these possibilities. Since the position of glucuronidation may be important in the mechanism of NDPS-induced nephrotoxicity, chemical derivatization in conjunction with mass spectrometry was used to characterize the glucuronide. The 2-NDHSA glucuronide conjugate was isolated from rat urine, derivatized with 3-pyridylcarbinol, and the derivatized metabolite was then analyzed by LC/MS/MS. Two known NDPS metabolites, 2-NDHSA and N-(3,5-dichlorophenyl)succinamic acid (NDPSA), were also isolated from rat urine and derivatized similarly. 3-Pyridinylcarbinol reacted rapidly with the carboxylic acid groups and formation of the picolinyl esters increased the ionization potential under positive ion conditions. The urinary glucuronide of 2-NDHSA was identified as an alcohol-linked glucuronide by examination of the molecular ions and the collision-induced dissociation (CID) product ion spectra of the derivatized products. When used in combination with mass spectrometry, derivatization of carboxylic acids with 3-pyridylcarbinol provided useful mass fragmentations and is a rapid way to obtain structural information about the position of glucuronidation of NDPS metabolites.

The effect of aromatic fluorine substitution on the nephrotoxicity and metabolism of N-(3,5-dichlorophenyl)succinimide in Fischer 344 rats

N-(3,5-Difluorophenyl)succinimide (DFPS) is a non-toxic analogue of the nephrotoxic fungicide N-(3,5-dichlorophenyl)succinimide (NDPS). Although NDPS must be metabolized to produce renal damage, the metabolic fate of DFPS is unknown. These studies were therefore designed to examine the nephrotoxic potential of putative DFPS metabolites and to determine if DFPS is metabolized differently from NDPS. Male Fischer-344 rats were administered (1.0 mmol/kg. i.p. in corn oil) DFPS, N-(3,5-difluorophenyl)succinamic acid (DFPSA), N-(3,5-difluorophenyl)-2-hydroxysuccinimide (DFHS), N-(3,5-difluorophenyl)-2- or -3-hydroxysuccinamic acids (2- and 3-DFHSA, respectively), N-(3,5-difluoro-4-hydroxyphenyl)succinimide (DFHPS). N-(3,5-difluoro-4-hydroxyphenyl) succinamic acid (DFHPSA) or corn oil only (1.2 ml/kg). Although some of the compounds produced changes in renal function and histology, these alterations were not indicative of irreversible kidney damage. DFPSA, 2-DFHSA, 3-DFHSA and DFHPSA were detected in the urine of rats 3 h after administration of 0.2 mmol/kg [14C]DFPS. The same metabolites were produced by isolated rat hepatocytes, but not by renal proximal tubule cells. Formation of the oxidative metabolites in vitro was prevented by the cytochrome P450 inhibitor 1-aminobenzotriazole. It appears that DFPS undergoes hepatic biotransformation similar to NDPS and that some of its metabolites have reversible effects on renal proximal tubules.