title: Beta-carotene as antioxidant.
abstract: OBJECTIVE
  Beta-carotene has been shown to exhibit a good radical-trapping antioxidant activity in vitro. We were interested to see if dietary beta-carotene in combination with various intake levels for vitamin A would also inhibit lipid peroxidation.
  
  
  METHODS
  Sixty male Wistar rats received vitamin A (as retinyl palmitate) for 14 weeks in the diet (40,000, 4000 and 400 IU/kg food). In the last 5 weeks one half of each group received beta-carotene (50 mg/kg food). Lipid peroxidation (induced by 10 microM Fe2+ and 0.2 mM ascorbate) was measured ex vivo in liver microsomes.
  
  
  RESULTS
  The beta-carotene-treated group had similar beta-carotene levels in liver microsomes (3.4 nmol per mg protein) as the other group, irrespective of vitamin A intake. No difference in lipid peroxidation was seen between the groups with different beta-carotene and vitamin A diets.
  
  
  CONCLUSIONS
  Beta-carotene is not effective in vitro as antioxidant in liver microsomes of rats fed beta-carotene with various intakes of vitamin A.
authors.affiliation: Department of Pharmacochemistry, Leiden/Amsterdam Center for Drug Research, Vrije Universiteit, Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Bast
authors.forename: R M
authors.initials: RM
authors.lastname: van der Plas
authors.forename: H
authors.initials: H
authors.lastname: van den Berg
authors.forename: G R
authors.initials: GR
authors.lastname: Haenen
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D004224:Diterpenes; D005296:Ferrous Compounds / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives / Q000494:pharmacology; D019207:beta Carotene / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D004224:Diterpenes; D005296:Ferrous Compounds; D000084562:Retinyl Esters; D019207:beta Carotene; D014801:Vitamin A; C014794:retinol palmitate; D005978:Glutathione; D001205:Ascorbic Acid