title: Structural, physicochemical and antioxidant properties of sodium alginate isolated from a Tunisian brown seaweed.
abstract: An original sodium alginate from Tunisian seaweed (Cystoseira barbata) was purified and characterized by circular dichroism (CD) and ATR-FTIR spectroscopies. ATR-FTIR spectrum of C. barbata sodium alginate (CBSA) showed the characteristic bands of mannuronic (M) and guluronic acids (G). The M/G ratio was estimated by CD (M/G = 0.59) indicating that CBSA was composed of 37% mannuronic acid and 63% guluronic acid. The analysis of viscosity of CBSA showed evidence of pseudoplastic fluid behaviour. The emulsifying capacity of CBSA was evaluated at different concentrations (0.25-3%), temperatures (25-100 °C) and pH (3.0-11.0). Compared to most commercial emulsifiers, the emulsion formulated by CBSA was found to be less sensitive to temperature changes and more stable at acidic pH. CBSA was examined for antioxidant properties using various antioxidant assays. CBSA exhibited important DPPH radical-scavenging activity (74% inhibition at a concentration of 0.5 mg/ml) and considerable ferric reducing potential. Effective hydroxyl-radical scavenging activity (82% at a concentration of 5 mg/ml) and potent protection activity against DNA breakage were also recorded for CBSA. However, in the linoleate-β-carotene system, CBSA exerted moderate antioxidant activity (60% at a concentration of 1.5 mg/ml). Therefore, CBSA can be used as a natural ingredient in food industry or in the pharmaceutical field.
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia. Electronic address: sabrine.sellimi@gmail.com.
authors.forename: Sabrine
authors.initials: S
authors.lastname: Sellimi
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia.
authors.forename: Islem
authors.initials: I
authors.lastname: Younes
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia.
authors.forename: Hanen Ben
authors.initials: HB
authors.lastname: Ayed
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia.
authors.forename: Hana
authors.initials: H
authors.lastname: Maalej
authors.affiliation: Laboratoire de Glycochimie et Reconnaissance Moléculaire, UMR 5032, Université Montpellier II, ENSCM, 8, rue de l'Ecole-Normale, 34296 Montpellier cedex, France.
authors.forename: Veronique
authors.initials: V
authors.lastname: Montero
authors.affiliation: Biomaterials Applications, 6, rue Lesdiguières, 38000 Grenoble, France.
authors.forename: Marguerite
authors.initials: M
authors.lastname: Rinaudo
authors.affiliation: Département de Biologie, Faculté des sciences de la nature et de la vie, Université de Djelfa, Algeria.
authors.forename: Mostefa
authors.initials: M
authors.lastname: Dahia
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia.
authors.forename: Tahar
authors.initials: T
authors.lastname: Mechichi
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hajji
authors.affiliation: Laboratoire de Génie Enzymatique et de Microbiologie, Université de Sfax, Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173-3038 Sfax, Tunisia.
authors.forename: Moncef
authors.initials: M
authors.lastname: Nasri
mesh_terms: D000464:Alginates / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000737:chemistry; D055598:Chemical Phenomena; D002942:Circular Dichroism; D053904:DNA Breaks, Single-Stranded / Q000187:drug effects; D004655:Emulsions / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D006603:Hexuronic Acids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D008970:Molecular Weight; D010084:Oxidation-Reduction; D000459:Phaeophyceae / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry; D012212:Rheology; D012624:Seaweed / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014416:Tunisia; D014783:Viscosity; D019207:beta Carotene / Q000737:chemistry
chemical_list: D000464:Alginates; D000975:Antioxidants; D001713:Biphenyl Compounds; D004655:Emulsions; D016166:Free Radical Scavengers; D006603:Hexuronic Acids; D010851:Picrates; D019207:beta Carotene; D017665:Hydroxyl Radical; D020723:Glucuronic Acid; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: ATR-FTIR; Antioxidant activity; Cicular dichroism; Cystoseira barbata; Emulsifying capacity; Sodium alginate; Viscosity