title: Structural characterization of polysaccharide obtained from red seaweed Gracilaria caudata (J Agardh).
abstract: Seaweeds are considered an important source of bioactive molecules. In this work the marine red alga Gracilaria caudata was submitted to aqueous extraction of their polysaccharides for 2 h at 100 °C. The polysaccharide fraction (PGC) presented a recovery of 32.8%. The sulfate content of PGC, calculated by S%, is 1 ± 0.2% and the degree of sulfation accounts for 0.13 ± 0.2. High-Performance Size-Exclusion Chromatography demonstrated that PGC consists of a high molecular weight polysaccharide (2.5 × 10(5)gmol(-1)). Chemical analysis of PGC was performed by microanalysis, infrared (FT-IR) and nuclear magnetic resonance (NMR, 1 and 2D) spectroscopy. The structure of PGC is mainly constituted by the alternating residues 3-linked-β-D-galactopyranose and 4-linked-3,6-α-L-anhydrogalactose; however some hydroxyl groups were substituted by methyl groups and pyruvic acid acetal. The biological precursor of 3,6-α-L-anhydrogalactose (6-sulfate-α-l-galactose) was also detected.
authors.affiliation: Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, CP 12.200, CEP 60455-760 Fortaleza, Ceará, Brazil.
authors.forename: Francisco C N
authors.initials: FC
authors.lastname: Barros
authors.forename: Draulio C
authors.initials: DC
authors.lastname: da Silva
authors.forename: Venicios G
authors.initials: VG
authors.lastname: Sombra
authors.forename: Jeanny S
authors.initials: JS
authors.lastname: Maciel
authors.forename: Judith P A
authors.initials: JP
authors.lastname: Feitosa
authors.forename: Ana L P
authors.initials: AL
authors.lastname: Freitas
authors.forename: Regina C M
authors.initials: RC
authors.lastname: de Paula
mesh_terms: D000362:Agar / Q000737:chemistry*; D005690:Galactose / Q000031:analogs & derivatives / Q000737:chemistry; D044724:Gracilaria / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011134:Polysaccharides / Q000737:chemistry / Q000302:isolation & purification; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011134:Polysaccharides; C086947:galactose 6-sulfate; D000362:Agar; D005690:Galactose