RESUMEN
The free and bound phenols have been measured in 20 fruits commonly consumed in the American diet. Phenols were measured colorimetrically using the Folin-Ciocalteu reagent with catechin as the standard after correction for ascorbic acid contribution. On a fresh weight basis, cranberry had the highest total phenols, and was distantly followed by red grape. Free and total phenol quality in the fruits was analyzed by using the inhibition of lower density lipoprotein oxidation promoted by cupric ion. Ascorbate had only a minor contribution to the antioxidants in fruits with the exception of melon, nectarine, orange, white grape, and strawberry. The fruit extracts' antioxidant quality was better than the vitamin antioxidants and most pure phenols, suggesting synergism among the antioxidants in the mixture. Using our assay, fruits had significantly better quantity and quality of phenol antioxidants than vegetables. Fruits, specifically apples and cranberries, have phenol antioxidants that can enrich lower density lipoproteins and protect them from oxidation. The average per capita consumption of fruit phenols in the U.S. is estimated to be 255 mg/day of catechin equivalents.
Asunto(s)
Antioxidantes/análisis , Frutas/química , Fenoles/análisis , Extractos Vegetales/químicaRESUMEN
Resorcinols (pentadecylresorcinol, olivetol, orcinol and resorcinol) exhibit antioxidant properties in liposomal systems. Antioxidant potency depends on the length of the alkyl chain. Pentadecylresorcinol has been demonstrated to be the most active antioxidant, indicating significance of its alkyl chain in a lipid bilayer. Quantum DFT computations demonstrated that hydroxyl group attached to the ring is the first target for the hydrogen abstraction after formation of the radical. However, the carbons of the side chain could also participate in the antioxidant properties of the alkylresorcinols. Formation of the radical at the hydroxyl oxygen initiates changes in the electron density which destabilise the whole system and subsequently leads to oxidation of the ring. The detailed study of lipophilicity and electrostatic properties of resorcinols is discussed.