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Drug Metab Dispos. 2019 Nov;47(11):1281-1290. doi: 10.1124/dmd.119.087460. Epub 2019 Sep 4.

Glutathione Conjugation and Protein Adduction Derived from Oxidative Debromination of Benzbromarone in Mice.

Author information

1
State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou, People's Republic of China (J.Z.); and Wuya College of Innovation (H.W., Y.F., Y.P., J.Z.) and Key Laboratory of Structure-Based Drug Design and Discovery (Ministry of Education), School of Pharmaceutical Engineering (W.W., B.G., Z.W., W.Z., S.W.), Shenyang Pharmaceutical University, Shenyang, Liaoning, People's Republic of China.
2
State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou, People's Republic of China (J.Z.); and Wuya College of Innovation (H.W., Y.F., Y.P., J.Z.) and Key Laboratory of Structure-Based Drug Design and Discovery (Ministry of Education), School of Pharmaceutical Engineering (W.W., B.G., Z.W., W.Z., S.W.), Shenyang Pharmaceutical University, Shenyang, Liaoning, People's Republic of China. yingpeng1999@163.com.
3
State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou, People's Republic of China (J.Z.); and Wuya College of Innovation (H.W., Y.F., Y.P., J.Z.) and Key Laboratory of Structure-Based Drug Design and Discovery (Ministry of Education), School of Pharmaceutical Engineering (W.W., B.G., Z.W., W.Z., S.W.), Shenyang Pharmaceutical University, Shenyang, Liaoning, People's Republic of China. zhengneu@yahoo.com.

Abstract

Benzbromarone (BBR), a uricosuric agent, has been known to induce hepatotoxicity, and its toxicity has a close relation to cytochrome P450-mediated metabolic activation. An oxidative debromination metabolite of BBR has been reported in microsomal incubations. The present study attempted to define the oxidative debromination pathway of BBR in vivo. One urinary mercapturic acid (M1) and one glutathione (GSH) conjugate (M2) derived from the oxidative debromination metabolite were detected in BBR-treated mice after solid phase extraction. M1 and M2 shared the same chromatographic behavior and mass spectral identities as those detected in N-acetylcysteine/GSH- and BBR-fortified microsomal incubations. The structure of M1 was characterized by chemical synthesis, along with mass spectrometry analysis. In addition, hepatic protein modification that occurs at cysteine residues (M'3) was observed in mice given BBR. The observed protein adduction reached its peak 4 hours after administration and occurred in a dose-dependent manner. A GSH conjugate derived from oxidative debromination of BBR was detected in livers of mice treated with BBR, and the formation of the GSH conjugate apparently took place earlier than the protein adduction. In summary, our in vivo work provided strong evidence for the proposed oxidative debromination pathway of BBR, which facilitates the understanding of the mechanisms of BBR-induced hepatotoxicity. SIGNIFICANCE STATEMENT: This study investigated the oxidative debromination pathway of benzbromarone (BBR) in vivo. One urinary mercapturic acid (M1) and one glutathione (GSH) conjugate (M2) derived from the oxidative debromination metabolite were detected in BBR-treated mice. M1 and M2 were also observed in microsomal incubations. The structure of M1 was characterized by chemical synthesis followed by mass spectrometry analyses. More importantly, protein adduction derived from oxidative debromination of BBR (M'3) was observed in mice given BBR, and occurred in dose- and time-dependent manners. The success in detection of GSH conjugate, urinary N-acetylcysteine conjugate, and hepatic protein adduction in mice given BBR provided solid evidence for in vivo oxidative debromination of BBR. The studies allowed a better understanding of the metabolic activation of BBR.

PMID:
31484654
DOI:
10.1124/dmd.119.087460

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