Role of Free Radicals and Biotransformation in Trichloronitrobenzene-Induced Nephrotoxicity In Vitro.

Gary Rankin,Christopher Racine,Connor Tyree,Monica Valentovic,Kathleen Brown,Dianne Anestis,Deborah Pope,Mason Dial,Jordan Tate

doi:10.3390/ijms18061165

Gary Rankin, Christopher Racine + Show 7 more

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https://doi.org/10.3390/ijms18061165

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Abstract

This study determined the comparative nephrotoxic potential of four trichloronitrobenzenes (TCNBs) (2,3,4-; 2,4,5-; 2,4,6-; and 3,4,5-TCNB) and explored the effects of antioxidants and biotransformation inhibitors on TCNB-induced cytotoxicity in isolated renal cortical cells (IRCC) from male Fischer 344 rats. IRCC were incubated with a TCNB up to 1.0 mM for 15–120 min. Pretreatment with an antioxidant or cytochrome P450 (CYP), flavin monooxygenase (FMO), or peroxidase inhibitor was used in some experiments. Among the four TCNBs, the order of decreasing nephrotoxic potential was approximately 3,4,5- > 2,4,6- > 2,3,4- > 2,4,5-TCNB. The four TCNBs exhibited a similar profile of attenuation of cytotoxicity in response to antioxidant pretreatments. 2,3,4- and 3,4,5-TCNB cytotoxicity was attenuated by most of the biotransformation inhibitors tested, 2,4,5-TCNB cytotoxicity was only inhibited by isoniazid (CYP 2E1 inhibitor), and 2,4,6-TCNB-induced cytotoxicity was inhibited by one CYP inhibitor, one FMO inhibitor, and one peroxidase inhibitor. All of the CYP specific inhibitors tested offered some attenuation of 3,4,5-TCNB cytotoxicity. These results indicate that 3,4,5-TCNB is the most potent nephrotoxicant, free radicals play a role in the TCNB cytotoxicity, and the role of biotransformation in TCNB nephrotoxicity in vitro is variable and dependent on the position of the chloro groups.

Highlights

Chloronitrobenzenes are widely used as chemical intermediates in the production of dyes, pesticides, drugs, and other commercial products [1,2,3,4,5]
For the inhibition of biotransformation, 2,4,5-TCNB-induced cytotoxicity was only reduced by pretreatment with isoniazid. These results suggest that 2,4,5-TCNB cytotoxicity involves free radicals, but the role of biotransformation enzymes involved in oxidation and/or reduction biotransformation reactions in 2,4,5-TCNB cytotoxicity is less clear
The results of this study demonstrated that cytotoxicity induced by 2,3,4, 2,4,6, and 3,4,5-TCNB was inhibited by pretreatment with at least one cytochrome P450 (CYP) inhibitor, flavin monooxygenase (FMO) inhibitors, and peroxidase inhibitors, suggesting that the nitro reduction-amino oxidation pathway was contributing to the production of nephrotoxic metabolites

Summary

Introduction

Chloronitrobenzenes are widely used as chemical intermediates in the production of dyes, pesticides, drugs, and other commercial products [1,2,3,4,5] Exposure to these compounds occurs primarily in an occupational setting, but chloronitrobenzenes are present in the environment from wastewater at industrial sites and from accidental spills [6,7,8]. Information concerning the potential toxicity induced by the chloronitrobenzenes comes primarily from studies on monochloronitrobenzenes (MCNBs). These compounds induce hematotoxicity, hepatotoxicity, immunotoxicity, splenotoxicity, and nephrotoxicity [9,10,11,12,13,14,15]. The toxicity induced by MCNBs has been studied to some degree, few studies have examined the toxicity induced by higher chlorinated nitrobenzenes (dichloro-, trichloro-, etc.), and it is generally believed that dichloronitrobenzenes (DCNBs) and trichloronitrobenzenes (TCNBs) have the potential to induce the same kinds of toxicities as the MCNBs

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