title: Antioxidant effect of flavonoids after ascorbate/Fe(2+)-induced oxidative stress in cultured retinal cells.
abstract: In this study, we investigated the structure-activity relationship of four flavonoids, i.e. eriodictyol, luteolin, quercetin, and taxifolin, in cultured retinal cells after ascorbate/Fe(2+)-induced oxidative stress. The relative order of antioxidant efficacy, determined by the thiobarbituric acid method, was the following: eriodictyol > quercetin > luteolin > taxifolin. Upon preincubation, the flavonoids were also effective in reducing the extent of lipid peroxidation. Oxidative stress, determined by the changes in fluorescence of 2',7'-dichlorodihydrofluorescein, was also decreased in the presence of the flavonoids, showing the following order of antioxidant efficacy: eriodictyol > taxifolin approximately quercetin > luteolin. Ascorbate/Fe(2+)-induced oxidative stress or incubation in the presence of the flavonoids did not significantly affect the viability of retinal cells. We also evaluated the degree of membrane partition of the flavonoids. In this system, the results strongly suggest that the higher antioxidant activity of the flavonoids is not correlated with the presence of a double bond at C(2)-C(3) and/or a hydroxyl group at C(3) on the C ring, but rather may depend on the capacity to inhibit the production of reactive oxygen species to interact hydrophobically with membranes. Eriodictyol was shown to be the most efficient antioxidant in protecting against oxidative stress induced by ascorbate/Fe(2+) in the retinal cells.
authors.affiliation: CEQUP/Laboratory of Pharmacognosy, Faculty of Pharmacy, R. Anibal Cunha, University of Porto, 4050-047, Porto, Portugal.
authors.forename: F M
authors.initials: FM
authors.lastname: Areias
authors.forename: A C
authors.initials: AC
authors.lastname: Rego
authors.forename: C R
authors.initials: CR
authors.lastname: Oliveira
authors.forename: R M
authors.initials: RM
authors.lastname: Seabra
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D004347:Drug Interactions; D005296:Ferrous Compounds / Q000494:pharmacology; D044950:Flavanones; D005419:Flavonoids / Q000494:pharmacology*; D005452:Fluoresceins / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000975:Antioxidants; D005296:Ferrous Compounds; D044950:Flavanones; D005419:Flavonoids; D005452:Fluoresceins; D017382:Reactive Oxygen Species; C065013:2',7'-dichlorodihydrofluorescein; D001205:Ascorbic Acid; C007619:eriodictyol