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

The Antiandrogenic Activity of the Fungicide N-(3, 5-Dichlorophenyl) Succinimide in In Vivo and In Vitro Assays

Antiandrogens can cause reproductive disorders in humans and wild animals. In the present study, we tested whether the fungicide N-(3, 5-dichlorophenyl) succinimide (NDPS) acts as an antiandrogen using in vitro and in vivo assays. A transient transfection system based on luciferase activity was utilized for in vitro analysis of the antiandrogeic activity of NDPS. Hershberger assay was used to analyze the antiandrogenic activity of NDPS in rats. The expressions of the androgen-responsive genes testosterone-repressed prostatic message-2 (TRPM-2) and prostate specific binding protein polypeptide C3 (PBP C3) in the rat ventral prostate were measured using real-time PCR. Our results indicated that NDPS can block 5-dehydrotestosterone (DHT)-induced androgen receptor (AR) activity in transiently transfected HepG2 cells (-5 log M). In the Hershberger assay, the weights of the seminal vesicles and levator ani/bulbocavernosus muscles were significantly decreased (P<0.05) in all NDPS groups, and the weights of the ventral prostate, dorsolateral prostate, and Cowper's glands were significantly decreased (P<0.05) in the 100 and 200 mg/kg NDPS groups. NDPS only decreased (P<0.05) the expression of PBP C3 and had no effect on the level of TRPM-2 (P>0.05). In conclusion, NDPS is a moderate antiandrogen that elicits antiandrogenic effects at least partly by antagonizing AR and increasing the expression of PBP C3.

Nephrotoxicity induced by C- and N-arylsuccinimides

The succinimide ring is incorporated into hundreds of compounds that are widely used as agricultural, industrial, and pharmaceutical agents. Some succinimide derivatives that contain an aryl group on the ethylene bridge of the succinimide ring (C-arylsuccinimides) or on the nitrogen atom (N-arylsuccinimides) induce nephrotoxicity in humans and/or laboratory animals. Acute toxicity induced by this general class of compounds is typically characterized as polyuric renal failure, while chronic nephrotoxicity is seen as chronic interstitial nephritis. In this review, the structure-nephrotoxicity relationships, biotransformation, and mechanisms of nephrotoxicity for the C- and N-arylsuccinimides are examined.

Nephrotoxic and hepatotoxic potential of imidazolidinedione-, oxazolidinedione- and thiazolidinedione-containing analogues of N-(3,5-dichlorophenyl)succinimide (NDPS) in Fischer 344 rats

Nephrotoxicity of the agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) in rats is believed to involve metabolism on the succinimide ring. To further investigate this hypothesis, we synthesized and tested the following NDPS analogues, which contain other cyclic imide rings and may therefore be metabolized differently than NDPS: 3-(3,5-dichlorophenyl)-2,4-oxazolidinedione (DCPO), 3-(3,5-dichlorophenyl)-2,4-imidazolidinedione (DCPI), 3-(3,5-dichlorophenyl)-1-methyl-2,4-imidazolidinedione (DCPM) and 3-(3,5-dichlorophenyl)-2,4-thiazolidinedione (DCPT). Male Fischer 344 rats were administered DCPO, DCPI, DCPM, DCPT (0.6 or 1.0 mmol/kg, i.p. in corn oil), NDPS (0.6 mmol/kg, i.p. in corn oil) or corn oil (4 ml/kg). As evidenced by diuresis, proteinuria, elevated blood urea nitrogen levels, increased kidney weights and proximal tubular damage, NDPS produced severe nephrotoxicity in the rats. In contrast, DCPO, DCPI, DCPM and DCPT were mild nephrotoxicants. None of the compounds elevated serum alanine transferase activity or liver weights in the rats, however DCPT produced centrilobular necrosis. These experiments confirm that NDPS-induced nephrotoxicity is critically dependent on the presence of the succinimide ring. Furthermore, replacement of the succinimide ring with a thiazolidinedione ring produced a more pronounced effect on the liver than on the kidney. Liver damage has been reported in type II diabetic patients taking troglitazone, rosiglitazone and pioglitazone. Since these compounds also contain a thiazolidinedione ring, DCPT may be useful for investigating the role of this structural feature in hepatotoxicity.

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.

Role of stereochemistry in N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA) nephrotoxicity

The nephrotoxicity induced by the agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is mediated through oxidative metabolites of NDPS. Oxidation of the succinimide ring in NDPS yields the nephrotoxic metabolites N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and its hydrolysis product N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA). The oxidation of NDPS on the succinimide ring also introduces an asymmetric carbon atom into these NDPS metabolites, so that R- and S- enantiomers of NDHS and 2-NDHSA are possible. The purpose of this study was to begin to explore the importance of the stereochemical orientation at the asymmetric carbon atom for the nephrotoxicity induced by NDPS metabolites. Male Fischer 344 rats were administered a single intraperitoneal (ip) injection of R-(+)- or S-(-)-2-NDHSA (0.05, 0.1 or 2.0 mmol/kg) or vehicle, and renal function was monitored for 48 h. R-2-NDHSA (0.1 mmol/kg) administration had little effect on renal function. R-2-NDHSA (0.2 mmol/kg) treatment induced mild diuresis on day 1, increased proteinuria, and a small increase in blood urea nitrogen (BUN) concentration, but no change in kidney weight or glucosuria. S-2-NDHSA (0.1 mmol/kg) induced marked nephrotoxicity as evidenced by diuresis on both post-treatment days, increased proteinuria, glucosuria, and increased kidney weight and BUN concentration. No evidence of hepatotoxicity was obtained in any treated group. Thus, the S-isomer of 2-NDHSA is a more potent nephrotoxicant than the R-isomer, and stereochemistry may play a role in NDPS metabolite-induced nephrotoxicity.

Nephrotoxic potential of N-(3,5-dichloro-4-fluorophenyl)succinimide in Fischer 344 rats: comparison with N-(3,4,5-trichlorophenyl)succinimide

Numerous structure-nephrotoxicity relationship studies from our laboratory have demonstrated that N-(3,5-dichlorophenyl)succinimide (NDPS) is one of the most potent nephrotoxicants among the N-arylsuccinimides. The purpose of this study was to extend our previous structure-nephrotoxicity relationship studies by examining the effect of addition of a fluoro verses a chloro group at the 4-phenyl position in NDPS. Male Fischer 344 rats (four rats/group) received a single intraperitoneal (i.p.) injection of N-(3,5-dichloro-4-fluorophenyl)succinimide (NDCFPS) or N-(3,4,5-trichlorophenyl)succinimide (NTCPS)(0.4 or 0.8 mmol/kg) or vehicle, and renal function monitored at 24 and 48 h. NDCFPS did not induce significant nephrotoxicity at either dose tested. In contrast, NTCPS (0.4 or 0.8 mmol/kg) induced marked nephrotoxicity characterized by diuresis, increased proteinuria, glucosuria, elevated kidney weight and increased blood urea nitrogen (BUN) concentration. NTCPS also induced marked proximal tubular necrosis at both doses tested. Neither NDCFPS nor NTCPS induced hepatotoxicity at either dose tested. The results of these experiments indicate that addition of a fluoro group at the 4-position on the phenyl ring of NDPS produces a nonnephrotoxicant NDPS derivative (NDCFPS), while addition of a chloro group at this site produces an NDPS derivative with similar nephrotoxic potential to NDPS. The mechanism for this differential effect between 4-halophenyl substitution is unclear, but may result from increased hydrolysis of the succinimide ring and/or increased clearance of N-arylsuccinimide metabolites when a fluoro group is added to the 4-position of the phenyl ring.

Tissue distribution, subcellular localization and covalent binding of 2-chloroaniline and 4-chloroaniline in Fischer 344 rats

Chloroanilines (CA) are widely used chemical intermediates which induce numerous toxicities including hematotoxicity, splenotoxicity, hepatotoxicity and nephrotoxicity. Although chloroaniline-induced hematotoxicity has been studied in detail, little information is available on the organ-directed toxicity seen following exposure to these agents. The purpose of this study was to examine and compare the excretion and distribution of two nephrotoxicant and hepatotoxicant chloroanilines (2- and 4-chloroaniline) to liver, kidney, spleen, plasma and erythrocytes. Subcellular distribution and covalent binding in kidney and liver were also determined. Male Fischer 344 rats (four per group) were administered [14C]-2-chloroaniline or [14C]-4-chloroaniline (0.5 or 1.0 mmol/kg; approximately 50 microCi/rat) intraperitoneally (i.p.). Urine, feces, blood and tissues were collected at 3 and 24 h. Both 2- and 4-chloroaniline-derived radioactivity were primarily renally excreted with < 1% excretion in the feces by 24 h post-treatment. Both chloroanilines accumulated mainly in liver (percentage of administered dose/total tissue), but kidney generally had similar or higher equivalent concentrations (micromol/g tissue) compared to liver. Subcellular distribution revealed that for both chloroanilines, the cytosolic fraction generally had the highest level of radioactivity independent of time or dose. Covalent binding was detected in both liver and kidney, with the highest concentration (pmol/mg protein) of binding observed in the hepatic microsomal fraction regardless of compound, dose or time studied. In general, 2-chloroaniline derived radioactivity was excreted faster, reached peak tissue concentrations earlier, disappeared from tissues faster and had less covalent binding in target tissue at 24 h than 4-chloroaniline-derived radioactivity. These results suggest that the increased toxic potential of 4-chloroaniline as compared to 2-chloroaniline may be due in part to a more prolonged and persistent accumulation of 4-chloroaniline and/or its metabolites in target tissue.