Inhibition of the metmyoglobin-induced peroxidation of linoleic acid by dietary antioxidants: Action in the aqueous vs. lipid phase

Abstract

The gastric digestion of food containing oxidizable lipids and iron catalysts for peroxide decomposition such as (met)myoglobin from muscle meat can be accompanied by an extensive formation of potentially toxic lipid hydroperoxides. An early protective action by dietary antioxidants in the gastro-intestinal tract is plausible, especially for poorly bioavailable antioxidants such as polyphenols. Hence, the ability of antioxidants to inhibit lipid peroxidation initiated by dietary iron in mildly acidic emulsions is a valuable and general model. In this work, the ability of some ubiquitous dietary antioxidants representative of the main antioxidant classes (alpha-tocopherol, the flavonol quercetin, beta-carotene) to inhibit the metmyoglobin-induced peroxidation of linoleic acid is investigated by UV-visible spectroscopy and HPLC in mildly acidic emulsions. The phenolic antioxidants quercetin and alpha-tocopherol come up as the most efficient peroxidation inhibitors. Inhibition by quercetin essentially proceeds in the aqueous phase via a fast reduction of an unidentified activated iron species (with a partially degraded heme) produced by reaction of metmyoglobin with the lipid hydroperoxides. This reaction is faster by, at least, a factor 40 than the reduction of ferrylmyoglobin (independently prepared by reacting metmyoglobin with hydrogen peroxide) by quercetin. By contrast, alpha-tocopherol mainly acts in the lipid phase by reducing the propagating lipid peroxyl radicals. The poorer inhibition afforded by beta-carotene may be related to both its slower reaction with the lipid peroxyl radicals and its competitive degradation by autoxidation and/or photo-oxidation.

Preparation of efficient quercetin delivery system on Zn-modified mesoporous SBA-15 silica carrier

“…Initially these effects have been attributed to the strong antioxidant properties of quercetin, because of its ability to scavenge free radicals and the influence on the intracellular redox status. The antioxidant action appears to be a combination of reaction with free radicals, inhibition of xanthine oxidation and lipid peroxidation [12][13][14] and metal ion complexation [15]. A vast number of data have unambiguously shown that quercetin is endowed by prominent anticancer activity, mediated by pleiotropic actions on malignant cell signaling pathways.…”

Role of Bax in quercetin-induced apoptosis in human prostate cancer cells

“…The natural product quercetin (3,5,7,3′,4′-pentahydroxyflavone), which is orally bioavailable, is a flavonoid found in many fruits and vegetables [3]. Through epidemiological studies and preliminary data, quercetin has been found to inhibit the onset/ growth of prostate cancer.…”

Heme Iron Intake, Dietary Antioxidant Capacity, and Risk of Colorectal Adenomas in a Large Cohort Study of French Women

“…Oxidation leads to the formation of secondary reactive end products, such as malondialdehyde or 4-hydroxynonenal, that are cytotoxic and genotoxic (5). The heme-induced lipid peroxidation can be inhibited in the gastrointestinal tract by some polyphenols and vitamins, redox components of plant origin, that are able to hamper the damaging effect of free radicals (15)(16)(17)(18)(19)(20)(21). To consider the global antioxidant capacity as well as synergistic interactions between dietary antioxidants, the assessment of dietary non-enzymatic antioxidant capacity (NEAC) has been applied to epidemiologic studies as well as human intervention trials (22,23).…”