title: Analysis of antioxidant compounds in sweet orange peel by HPLC-diode array detection-electrospray ionization mass spectrometry.
abstract: HPLC-diode array detection-electrospray ionization mass spectrometry was used to determine qualitatively and quantitatively the flavonoid content of several fractions and residues of extracts of Greek navel sweet orange peel (Citrus sinensis) from the region of southern Greece (Leonidi-Tripoli). The main groups of flavonoids found according to HPLC retention times, spectral data and literature references were polymethoxylated flavones, C-glycosylated flavones, O-glycosylated flavones, O-glycosylated flavanones, flavonols and phenolic acids and their derivatives. The ethyl acetate fraction which has been shown in previous work to possess the best radical scavenging activity among the others was found to contain C-glycosylated flavones, polymethoxylated flavones, O-glycosylated flavones, O-glycosylated flavanones, two phenolic acid derivatives and two unknown compounds, all in low concentrations. The group of C-glycosylated flavones was reported for the first time in the peel of Navel sweet orange. The C-glycosylated flavones found according to their spectral characteristics and literature were 6-C-beta-glucosyldiosmin, 6,8-di-C-glucopyranosylapigenin, 6,8-di-C-beta-glucosyldiosmin and two unknown. The results suggest that the ethyl acetate fraction of navel Citrus sinensis peel consists of significant antioxidant compounds and can be used as a food additive of natural origin or a pharmaceutical supplement using as a source of peel the byproducts of the orange juice industry.
authors.affiliation: Chemical Engineering Department, Faculty of Engineering, Aristotle University of Thessalonica, Thessalonica 54124, Greece. managnos@auth.gr
authors.forename: Maria A
authors.initials: MA
authors.lastname: Anagnostopoulou
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Kefalas
authors.forename: Eugenios
authors.initials: E
authors.lastname: Kokkalou
authors.forename: Andreana N
authors.initials: AN
authors.lastname: Assimopoulou
authors.forename: Vassilios P
authors.initials: VP
authors.lastname: Papageorgiou
mesh_terms: D000085:Acetates; D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D032084:Citrus sinensis / Q000737:chemistry*; D005419:Flavonoids / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005638:Fruit / Q000737:chemistry*; D006031:Glycosylation; D006115:Greece; D062385:Hydroxybenzoates / Q000032:analysis / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013329:Structure-Activity Relationship
chemical_list: D000085:Acetates; D000975:Antioxidants; D005419:Flavonoids; D016166:Free Radical Scavengers; D062385:Hydroxybenzoates; D010936:Plant Extracts; C007650:ethyl acetate; C017616:phenolic acid