title: Caffeic acid as antioxidant in fish muscle: mechanism of synergism with endogenous ascorbic acid and alpha-tocopherol.
abstract: In an emulsion of corn oil in water with the addition of caffeic acid (Caf-OH) and alpha-tocopherol (alpha-TOH), Caf-OH was found to be very active in delaying lipid oxidation without affecting significantly the kinetics for alpha-TOH degradation. In contrast, Caf-OH addition to fish muscle retarded both the degradation of endogenous alpha-TOH and the propagation of lipid oxidation, measured by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS), with increasing effect with increasing Caf-OH addition (55.5-555.1 micromol/kg). Electron spin resonance (ESR) spectroscopy confirmed a higher capacity of Caf-OH to regenerate alpha-TOH via reduction of the alpha-tocopheroxyl radical compared to other cinnamic acid derivatives (o-coumaric, ferulic, and chlorogenic acids). Degradation of endogenous ascorbate (AscH(-)) was accelerated at higher concentration of Caf-OH in fish tissue, suggesting a role of AscH(-) in the regeneration of Caf-OH. These results indicate that the antioxidant mechanism of Caf-OH implies the protection of endogenous alpha-TOH localized in tissue membranes where lipid oxidation is initiated and, at the same time, Caf-OH regeneration by the endogenous AscH(-). These combined effects result in a stronger antioxidant protection against lipid oxidation by favoring, as a final point, the protection of alpha-TOH, which is suggested as the last defense of fish muscle against lipid oxidation.
authors.affiliation: Instituto de Investigaciones Marinas, Eduardo Cabello, Vigo, Spain. jacobo@iim.csic.es
authors.forename: Jacobo
authors.initials: J
authors.lastname: Iglesias
authors.forename: Manuel
authors.initials: M
authors.lastname: Pazos
authors.forename: Mogens L
authors.initials: ML
authors.lastname: Andersen
authors.forename: Leif H
authors.initials: LH
authors.lastname: Skibsted
authors.forename: Isabel
authors.initials: I
authors.lastname: Medina
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000737:chemistry / Q000378:metabolism*; D002109:Caffeic Acids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D004357:Drug Synergism; D005399:Fishes / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D024502:alpha-Tocopherol / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D002109:Caffeic Acids; D024502:alpha-Tocopherol; D001205:Ascorbic Acid; C040048:caffeic acid