title: Antioxidant properties of prepared blueberry (Vaccinium myrtillus) extracts.
abstract: A blueberry extract (A) and two anthocyanin-derived extracts (B and C) were prepared. The contents of polyphenols, flavonoids, anthocyanins, and anthocyanin-derived pigments of the extracts were determined for the first time. The pigment profile of blueberry extract A corresponded to 15 anthocyanins, whereas extract B was mainly composed of anthocyanin-pyruvic acid adducts of the blueberry original anthocyanins and extract C was mainly composed of the respective vinylpyranoanthocyanin-catechins (portisins). The extracts' abilities to inhibit lipid peroxidation, induced by 2,2'-azobis(2-methyl-propanimidamide) dihydrochloride in a liposomal membrane system were examined. The antioxidant capacities of the extracts were evaluated through monitoring oxygen consumption and by measuring the formation of conjugated dienes. All of the extracts provided protection of membranes against peroxyl radicals by increasing the induction time of oxidation. This effect increased with the polyphenol content and with the structural complexity of the anthocyanin-derived pigments of the extracts. The pigments present in extract C seemed to induce a higher protection of the liposome membranes toward oxidation. In addition, the antiradical properties and the reducing power of the extracts were determined by using DPPH and FRAP methods, respectively. The results from these assays were in agreement with those obtained with the liposome membranes.
authors.affiliation: Centro de Investigação em Química, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Faria
authors.forename: Joana
authors.initials: J
authors.lastname: Oliveira
authors.forename: Patrícia
authors.initials: P
authors.lastname: Neves
authors.forename: Paula
authors.initials: P
authors.lastname: Gameiro
authors.forename: Celestino
authors.initials: C
authors.lastname: Santos-Buelga
authors.forename: Victor
authors.initials: V
authors.lastname: de Freitas
authors.forename: Nuno
authors.initials: N
authors.lastname: Mateus
mesh_terms: D000872:Anthocyanins / Q000032:analysis; D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000032:analysis; D016166:Free Radical Scavengers / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D015227:Lipid Peroxidation / Q000187:drug effects; D010101:Oxygen Consumption; D010636:Phenols / Q000032:analysis; D010936:Plant Extracts / Q000737:chemistry*; D059808:Polyphenols; D029796:Vaccinium / Q000737:chemistry*
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D005419:Flavonoids; D016166:Free Radical Scavengers; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols