title: Antioxidant activity of dietary canthaxanthin.
abstract: It has been suggested that canthaxanthin (CX), beta-carotene, and other carotenoids may inhibit carcinogenesis via antioxidant activity. CX has been shown to inhibit lipid peroxidation in liposomes; this experiment was designed to assess the antioxidant activity of CX in biological membranes. Chicks were fed semipurified diets supplemented with placebo beadlets or CX beadlets (5 g beadlets/kg diet; 0.5 g CX/kg diet) for five weeks. Diets were deficient in vitamin E and selenium to maximize the power of detecting an antioxidant effect of CX and to induce exudative diathesis, which is a vitamin E and selenium deficiency disease of chicks. Dietary CX had no effect on the onset, incidence, or severity of exudative diathesis. Liver homogenates from CX-fed chicks exhibited significantly (p = 0.02) decreased formation of thiobarbituric acid-reactive substances over time in ferrous ion-induced peroxidations. Because dietary CX increased hepatic alpha-tocopherol content, subsequent peroxidations were conducted in membrane fractions prepared from placebo and CX livers matched for alpha-tocopherol content. In this system, CX was marginally but inconsistently protective against peroxidation at both 15 torr O2 (p = 0.12) and 150 torr O2 (p = 0.07). Nanomolar changes in hepatic alpha-tocopherol, unlike CX, substantially altered rates of peroxidation. These results suggest that under these conditions, dietary CX increased resistance to lipid peroxidation primarily by enhancing membrane alpha-tocopherol levels and secondarily by providing weak direct antioxidant activity.
authors.affiliation: Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06510.
authors.forename: S T
authors.initials: ST
authors.lastname: Mayne
authors.forename: R S
authors.initials: RS
authors.lastname: Parker
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D016644:Canthaxanthin; D002338:Carotenoids / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D002645:Chickens; D004032:Diet; D004487:Edema / Q000378:metabolism; D005260:Female; D015227:Lipid Peroxidation / Q000187:drug effects*; D008099:Liver / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000032:analysis / Q000378:metabolism; D011201:Poultry Diseases / Q000378:metabolism; D012643:Selenium / Q000172:deficiency; D013858:Thiobarbiturates / Q000032:analysis / Q000378:metabolism; D014810:Vitamin E / Q000032:analysis; D014811:Vitamin E Deficiency / Q000378:metabolism
chemical_list: D000975:Antioxidants; D008563:Membrane Lipids; D013858:Thiobarbiturates; D014810:Vitamin E; D002338:Carotenoids; D016644:Canthaxanthin; D012643:Selenium; C029684:thiobarbituric acid