title: Minor polysaccharidic constituents from the red seaweed Hypnea musciformis. Appearance of a novel branched uronic acid.
abstract: Two polysaccharide fractions isolated from Hypnea musciformis after room temperature- and hot water extraction, soluble after KCl precipitation of the more abundant carrageenans, were subfractionated by ion-exchange chromatography eluting with increasing concentrations of NaCl. The lowest NaCl concentration (0.2M) eluted agarans. The dl-hybrids (or mixtures) eluted at intermediate concentrations of NaCl. The d/l-galactose ratio and the sulfate proportion increased with the NaCl concentration. Different types of substitution were present, mainly at C-3 with sulfate, Xyl and methylated Gal stubs, as well as low amounts of 3,6-AnGal. A novel constituent, identified as 3-C-carboxy-d-erythrose1in its β-furanosic form, was found linked to C-6 of β-Gal units. A search carried out in other species like Iridaea undulosa and Kappaphycus alvarezii also revealed the same constituent. Finally, the late-eluting fractions were mostly carrageenans, with a structure consistent with that of a κ/ι/ν-carrageenan hybrid.
authors.affiliation: Departamento de Química Orgánica-CIHIDECAR/CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors.forename: Vanina A
authors.initials: VA
authors.lastname: Cosenza
authors.affiliation: Departamento de Química Orgánica-CIHIDECAR/CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Navarro
authors.affiliation: Departamento de Química Orgánica-CIHIDECAR/CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina. Electronic address: stortz@qo.fcen.uba.ar.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Stortz
mesh_terms: D002351:Carrageenan; D011134:Polysaccharides / Q000302:isolation & purification*; D000461:Rhodophyta / Q000737:chemistry*; D012624:Seaweed / Q000737:chemistry*; D014574:Uronic Acids / Q000302:isolation & purification*
chemical_list: D011134:Polysaccharides; D014574:Uronic Acids; D002351:Carrageenan
keywords: 3-C-carboxy-d-erythrofuranose; Agarans; Apiuronic acid; Carrageenans; Hypnea musciformis