title: Dietary flavonoids fail to suppress F2-isoprostane formation in vivo.
abstract: Dietary antioxidants, including alpha-tocopherol (alpha-TOH) and polyphenolic flavonoid compounds, have been the subject of much research interest, but few studies have investigated interactions between these two antioxidants in vivo. We have conducted a feeding study to determine if supplementation with dietary flavonoids or polyphenol-containing compounds will provide antioxidant protection in tocopherol-deficient animals or exceed the antioxidant protection provided by alpha-TOH alone, using the sensitive and specific measure of lipid peroxidation, F2-isoprostanes. Seventy-two male Sprague Dawley rats were divided into 12 treatment groups to receive either alpha-TOH-sufficient or -deficient AIN93-G diet supplemented with one of five compounds: 0.5% quercetin, catechin, or epicatechin; or 1% cocoa powder or lignin. The fat source was polyunsaturated oil, increased from 7 to 11.05% (w/w with diet) to maximize lipid peroxidation while staying within a physiological range. After 7 weeks of treatment, animals were sacrificed with plasma and hearts analyzed to determine differences in F2-isoprostane levels. None of the treatment compounds significantly decreased plasma or heart F2-isoprostanes compared to the control beyond the significant protection displayed by alpha-tocopherol. We conclude that under these experimental conditions, quercetin, catechin, and epicatechin do not suppress lipid peroxidation in vivo.
authors.affiliation: Department of Food Science, North Carolina State University, Raleigh, NC 27695-7624, USA.
authors.forename: Joye K
authors.initials: JK
authors.lastname: Willcox
authors.forename: George L
authors.initials: GL
authors.lastname: Catignani
authors.forename: L Jackson
authors.initials: LJ
authors.lastname: Roberts
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology; D001835:Body Weight; D019587:Dietary Supplements; D028441:F2-Isoprostanes / Q000096:biosynthesis* / Q000097:blood*; D005419:Flavonoids / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D015227:Lipid Peroxidation; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000975:Antioxidants; D028441:F2-Isoprostanes; D005419:Flavonoids