title: Ferrous-iron-induced oxidation in chicken liver slices as measured by hemichrome formation and thiobarbituric acid-reactive substances: effects of dietary vitamin E and beta-carotene.
abstract: Hemichrome formation in chicken liver slices was determined by employing a Heme Protein Spectra Analysis Program (HPSAP) on the visible spectrum of the liver tissue. Relative hemichrome formation (RHF) in liver tissue exposed to ferrous iron for 1 h at 37 degrees C could be predicted according to the general catalytic equation RHF = k.[Fe2+]/(Ap + [Fe2+]), with k = 132 +/- 30, where the factor Ap represents the additive antioxidative potential in the liver tissue. RHF in Fe2+ exposed liver slices incubated at 37 degrees C for 1 h correlated significantly with formation of thiobarbituric acid-reactive substances (TBARS) (r = .77, P < .0001). RHF was found to decrease significantly with increasing vitamin E concentration in liver tissue exposed to ferrous iron (1 h, 37 degrees C). However, the influence of beta-carotene on RHF in ferrous-iron exposed liver slices (1 h, 37 degrees C) was less evident, as the concentration of Fe2+ was found to be decisive for whether beta-carotene acted as an antioxidant or a prooxidant under the conditions in question. Results in the liver slice model system regarding the effect of vitamin E and beta-carotene on iron overload were supported in a subsequent in vivo iron injection experiment with chicks. These observations indicate that RHF is a sensitive marker for ferrous-iron-induced oxidative damage in the present tissue slice system.
authors.affiliation: Department of Dairy and Food Sciences, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
authors.forename: H J
authors.initials: HJ
authors.lastname: Andersen
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: L J
authors.initials: LJ
authors.lastname: Pellett
authors.forename: A L
authors.initials: AL
authors.lastname: Tappel
mesh_terms: D000818:Animals; D002338:Carotenoids / Q000008:administration & dosage / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D002645:Chickens; D004032:Diet; D005296:Ferrous Compounds / Q000494:pharmacology*; D006420:Hemeproteins / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism*; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology*; D019207:beta Carotene
chemical_list: D005296:Ferrous Compounds; D006420:Hemeproteins; D017392:Thiobarbituric Acid Reactive Substances; C001332:hemichrome; D019207:beta Carotene; D014810:Vitamin E; D002338:Carotenoids; D002374:Catalase; D013482:Superoxide Dismutase