title: Inhibition of apple polyphenol oxidase activity by procyanidins and polyphenol oxidation products.
abstract: The rate of consumption of dissolved oxygen by apple polyphenol oxidase in cider apple juices did not correlate with polyphenol oxidase activity in the fruits and decreased faster than could be explained by the decrease of its polyphenolic substrates. The kinetics parameters of a crude polyphenol oxidase extract, prepared from apple (Braeburn cultivar), were determined using caffeoylquinic acid as a substrate. Three apple procyanidin fractions of n 80, 10.5, and 4 were purified from the parenchyma of cider apples of various cultivars. Procyanidins, caffeoylquinic acid, (-)-epicatechin, and a mixture of caffeoylquinic acid and (-)-epicatechin were oxidized by reaction with caffeoylquinic acid o-quinone in order to form oxidation products. All the fractions were evaluated for their inhibitory effect on PPO activity. Native procyanidins inhibited polyphenol oxidase activity, the inhibition intensity increasing with n. The polyphenol oxidase activity decreased by 50% for 0.026 g/L of the fraction of n 80, 0.17 g/L of the fraction of n 10.5, and 1 g/L of the fraction of n 4. The inhibitory effect of oxidized procyanidins was twice that of native procyanidins. Oxidation products of caffeoylquinic acid and (-)-epicatechin also inhibited polyphenol oxidase.
authors.affiliation: Unité de Recherches Cidricoles, Biotransformation des Fruits et Légumes, INRA, Domaine de la Motte, BP 35327, 35653 Le Rheu Cedex, France. lebourve@rennes.inra.fr
authors.forename: Carine
authors.initials: C
authors.lastname: Le Bourvellec
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Le Quéré
authors.forename: Philippe
authors.initials: P
authors.lastname: Sanoner
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Drilleau
authors.forename: Sylvain
authors.initials: S
authors.lastname: Guyot
mesh_terms: D001628:Beverages / Q000032:analysis; D044946:Biflavonoids; D002392:Catechin / Q000378:metabolism / Q000494:pharmacology*; D004156:Catechol Oxidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000378:metabolism*; D005638:Fruit / Q000201:enzymology*; D007700:Kinetics; D027845:Malus / Q000201:enzymology*; D010084:Oxidation-Reduction; D010636:Phenols / Q000378:metabolism*; D059808:Polyphenols; D044945:Proanthocyanidins; D011801:Quinic Acid / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D044946:Biflavonoids; D004791:Enzyme Inhibitors; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D044945:Proanthocyanidins; C472707:caffeoylquinic acid; D011801:Quinic Acid; C017674:procyanidin; D002392:Catechin; D004156:Catechol Oxidase