In vivo identification of aflatoxin-induced free radicals in rat bile.
Aflatoxin B1 (AFB1) is a potent hepatocarcinogen. We have recently detected [via electron spin resonance (ESR) spectroscopy] free radicals in vivo in rat bile following AFB1 metabolism using the spin trapping [alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone (4-POBN)] technique. The aim of the present study was to identify the trapped free radical intermediates from the in vivo hepatic metabolism of AFB1. Rats were treated simultaneously with AFB1 (3 mg/kg i.p.) and the spin trapping agent 4-POBN (1 g/kg i.p.), and bile was collected over a period of 1 h at 20 min intervals. On-line high performance liquid chromatography (HPLC) coupled to ESR was used to identify an arachidonic acid-derived radical adduct of 4-POBN in rat bile, and a methyl adduct of 4-POBN from the reaction of hydroxyl radicals with carbon-13-labeled dimethyl sulfoxide ((13)C-DMSO). The effect of metabolic inhibitors, such as desferoxamine mesylate (DFO), an iron chelator, 2-dimethylaminoethyl-2,2-diphenylvalerate hydrochloride (SKF) 525A, a cytochrome P-450 inhibitor, and gadolinium chloride (GdCl(3)), a Kupffer cell inactivator, on in vivo aflatoxin-induced free radical formation were also studied. It was found that there was a significant decrease in radical formation as a result of DFO, SKF525A and GdCl(3) inhibition. Trapped 4-POBN radical adducts were also detected in rat bile following the in vivo metabolism of aflatoxin-M1, one of the hydroxylated metabolites of AFB1.
Towner
Rheal A
RA
Free Radical Biology and Aging Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA. Rheal-Tower@omrf.ouhsc.edu
Qian
Steven Y
SY
Kadiiska
Maria B
MB
Mason
Ronald P
RP
D016604:Aflatoxin B1 / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D016718:Arachidonic Acid / Q000737:chemistry; D001646:Bile / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D065607:Cytochrome P-450 Enzyme Inhibitors; D003676:Deferoxamine / Q000031:analogs & derivatives / Q000494:pharmacology; D004121:Dimethyl Sulfoxide; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism*; D005682:Gadolinium / Q000494:pharmacology; D007502:Iron Chelating Agents / Q000494:pharmacology*; D008297:Male; D009589:Nitrogen Oxides; D011335:Proadifen / Q000494:pharmacology; D011725:Pyridines; D051381:Rats; D017207:Rats, Sprague-Dawley; D013113:Spin Labels; D019097:Spin Trapping
D000893:Anti-Inflammatory Agents; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D005609:Free Radicals; D007502:Iron Chelating Agents; D009589:Nitrogen Oxides; D011725:Pyridines; D013113:Spin Labels; C043438:alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone; D016718:Arachidonic Acid; D016604:Aflatoxin B1; D011335:Proadifen; D005682:Gadolinium; D003676:Deferoxamine; C038958:gadolinium chloride; D004121:Dimethyl Sulfoxide