title: Identification and antioxidant potential of flavonoids and low molecular weight phenols in olive cultivar chemlali growing in Tunisia.
abstract: Increasing interest in phenolic compounds in olives is due to their antioxidant and health-enhancing properties. In this study the phenolics in fruits of the Tunisian olive cultivar Chemlali were extracted by methanol-water and fractionated using Sephadex LH-20 column chromatography. The identification of phenolic monomers and flavonoids was based on separation by high-performance liquid chromatography equipped with a diode array detector followed by liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry analysis. Oleuropein, a secoiridoid glycoside esterified with a phenolic acid, was the major compound. Eight phenolic monomers and 12 flavonoids were also identified in Chemlali olives. Five flavonoids were isolated and purified using Sephadex LH-20 column chromatography and preparative paper chromatography. The antioxidant activity of the extract and the purified compounds was evaluated by measuring the radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl and by using the beta-carotene-linoleate model assay. Acid hydrolysis of the extract enhanced its antioxidant activity. Hydroxytyrosol and quercetin showed antioxidant activities similar to that of 2,6-di-tert-butyl-4-methylphenol. A hydroxyl group at the ortho position at 3' on the B ring of the flavonoid nucleus could contribute to the antioxidant activity of the flavonoids.
authors.affiliation: Laboratoire des Bio-procédés, Centre de Biotechnologie de Sfax, B.P. K, 3038 Sfax, Tunisia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bouaziz
authors.forename: Renee J
authors.initials: RJ
authors.lastname: Grayer
authors.forename: Monique S J
authors.initials: MS
authors.lastname: Simmonds
authors.forename: Mohamed
authors.initials: M
authors.lastname: Damak
authors.forename: Sami
authors.initials: S
authors.lastname: Sayadi
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D001713:Biphenyl Compounds; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000032:analysis* / Q000494:pharmacology; D005638:Fruit / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D057888:Iridoid Glucosides; D039823:Iridoids; D008970:Molecular Weight; D031658:Olea / Q000737:chemistry* / Q000254:growth & development; D010636:Phenols / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D010851:Picrates / Q000737:chemistry; D011714:Pyrans / Q000032:analysis; D014416:Tunisia; D019207:beta Carotene
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D005419:Flavonoids; D057888:Iridoid Glucosides; D039823:Iridoids; D010636:Phenols; D010851:Picrates; D011714:Pyrans; D019207:beta Carotene; C002769:oleuropein; C004931:1,1-diphenyl-2-picrylhydrazyl