title: Free radical formation and erythrocyte membrane alterations during MetHb formation induced by the BHA metabolite, tert-butylhydroquinone.
abstract: Erythrocyte membranes are altered as a consequence of oxidative stress following the incubation of intact erythrocytes with one of the major metabolites of the antioxidant butylated hydroxyanisole (BHA), tertbutylhydroquinone(tBHQ). Arather persistent semiquinone radical was observed by electron spin resonance (ESR) spectroscopy when tBHQ was incubated with either homogeneous oxyhemoglobin solutions or suspensions of intact erythrocytes. Erythrocyte ghosts prepared from fresh control erythrocytes and ghosts from erythrocytes preincubated with BHA and its metabolite, tBHQ, were subjected to polyacrylamide gel electrophoresis (SDS-PAGE). Only minor changes of the electrophoresis pattern relative to the control was observed in the BHA incubations whereas tBHQ significantly increased the amount of high molecular weight degradation products of erythrocyte membrane constituents. These changes were only observed when incubations were performed in the presence of oxygen. In control experiments where heme oxygen was replaced by carbon monoxide, no membrane degradation products appeared. These observations can be interpreted in terms of metabolic activation of the antioxidant BHAvia tBHQ to the tert-butylsemiquinone free radical and finally to the corresponding quinone, thereby leading to harmful effects on erythrocyte membrane structures. Moreover, deleterious effects on other biological membranes are also likely to occur.
authors.affiliation: Institute of Pharmacology and Toxicology, Veterinary University of Vienna, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Stolze
authors.forename: H
authors.initials: H
authors.lastname: Nohl
mesh_terms: D000818:Animals; D000975:Antioxidants; D002083:Butylated Hydroxyanisole / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D005609:Free Radicals; D006873:Hydroquinones / Q000494:pharmacology*; D008706:Methemoglobin / Q000378:metabolism*; D018384:Oxidative Stress; D010108:Oxyhemoglobins / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D006873:Hydroquinones; D010108:Oxyhemoglobins; D013439:Sulfhydryl Reagents; D002083:Butylated Hydroxyanisole; D008706:Methemoglobin; C018855:2-tert-butylhydroquinone; D005033:Ethylmaleimide