title: Inhibition of hemoglobin- and iron-promoted oxidation in fish microsomes by natural phenolics.
abstract: Natural phenolic antioxidants have been tested in hake (Merluccious merluccious) microsomes as inhibitors of lipid oxidation promoted by fish muscle prooxidants: hemoglobin (Hb), enzymatic NADH-iron and nonenzymatic ascorbate-iron. The phenolics selected were as follows: (a) a grape phenolic extract (OW), (b) a fraction (IV) with isolated grape procyanidins with a medium-low degree of polymerization and galloylation percentage, (c) hydroxytyrosol obtained from olive oil byproducts, and (d) a synthetic phenolic antioxidant, propyl gallate. All compounds delayed lipid oxidation activated by Hb, enzymatic NADH-iron, and nonenzymatic ascorbate-iron, excluding hydroxytyrosol that was not an effective antioxidant on oxidation promoted by nonenzymatic iron. The relative antioxidant efficiency was independent of the prooxidant system, IV > propyl gallate > OW > hydroxytyrosol, and showed a positive correlation with their incorporation into microsomes (p < 0.05). The reducing capacity or ability for donating electrons and the chelating properties may also contribute to the antioxidant activity of phenolics, although these factors were less decisive than their affinity for incorporating into the microsomes. Conversely, the inhibition of Hb oxidation by phenolics and their polarity did not seem to play an important role on antioxidant mechanism. These results stressed the importance of incorporating the exogenous antioxidants into the membranes where are located key substances for fish lipid oxidation (highly unsaturated phospholipids, iron-reducing enzymes, and endogenous alpha-tocopherol).
authors.affiliation: Instituto de Investigaciones Marinas (CSIC), Eduardo Cabello 6, 36208 Vigo, Spain. mpazos@iim.csic.es
authors.forename: Manuel
authors.initials: M
authors.lastname: Pazos
authors.forename: Salomé
authors.initials: S
authors.lastname: Lois
authors.forename: Josep Lluís
authors.initials: JL
authors.lastname: Torres
authors.forename: Isabel
authors.initials: I
authors.lastname: Medina
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005638:Fruit / Q000737:chemistry; D048388:Gadiformes; D006454:Hemoglobins / Q000494:pharmacology*; D007501:Iron / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects; D008861:Microsomes / Q000187:drug effects* / Q000378:metabolism; D000069463:Olive Oil; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry / Q000494:pharmacology*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000494:pharmacology; D010938:Plant Oils / Q000737:chemistry; D044945:Proanthocyanidins / Q000494:pharmacology; D011435:Propyl Gallate / Q000494:pharmacology; D027843:Vitis / Q000737:chemistry
chemical_list: D000975:Antioxidants; D006454:Hemoglobins; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; D044945:Proanthocyanidins; C005975:3,4-dihydroxyphenylethanol; D011435:Propyl Gallate; D007501:Iron; D010626:Phenylethyl Alcohol