On the mechanisms of 3-tert-butyl-4-hydroxyanisole- and its metabolites-induced cytotoxicities in isolated rat hepatocytes.
The cytotoxic effects of 3-tert-butyl-4-hydroxyanisole (BHA) and its metabolites, 3-tert-butylhydroquinone (tBHQ) and 3-tert-butyl-4,5-dihydroxyanisole (BHA-OH), were investigated in freshly isolated rat hepatocytes. These compounds caused a time-dependent cell death accompanied by loss of intracellular ATP, glutathione (GSH) and protein thiols at concentration of 0.5 mM. Supplementation of the hepatocyte suspension with 5 mM N-acetylcysteine, a precursor of intracellular GSH, significantly delayed the onset of cytotoxicity induced by BHA-OH and tBHQ; the loss of intracellular ATP, GSH and protein thiols was also prevented. Although N-acetylcysteine did not affect BHA disappearance in the cell suspension, disappearance of tBHQ and formation of tBHQ-GSH conjugate were stimulated by N-acetylcysteine. In addition, N-acetylcysteine prevented BHA-OH disappearance and 3-tert-butyl-5-methoxy-1,2-benzoquinone (BHA-Q) formation. In isolated hepatic mitochondria, BHA, tBHQ and BHA-OH impaired respiration related to oxidative phosphorylation; tert-butylquinone (tBQ) and BHA-Q, quinones derived from tBHQ and BHA-OH, resulted in the significant inhibition of mitochondrial respiration. These results indicate that BHA-OH is the most cytotoxic followed by tBHQ and BHA and that protein thiols and mitochondrial respiratory system are important targets for BHA and its intermediates.
Nakagawa
Y
Y
Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan.
Nakajima
K
K
Moore
G
G
Moldéus
P
P
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002083:Butylated Hydroxyanisole / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000494:pharmacology*; D002469:Cell Separation; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D006873:Hydroquinones / Q000494:pharmacology; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344
D006873:Hydroquinones; D002083:Butylated Hydroxyanisole; C018855:2-tert-butylhydroquinone; C044874:3-tert-butyl-4,5-dihydroxyanisole; D000111:Acetylcysteine