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vol.52 issue1IN VITRO TRYPANOCIDAL ACTIVITY AND CHEMICAL CONSTITUENTS OF ASPILIA PLATYPHYLLA (BAKER) BLAKEMICROWAVE-ASSISTED RAPID SYNTHESIS OF PHYSCION’S DERIVATIVES UNDER SOLVENT FREE CONDITION author indexsubject indexarticles search
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Journal of the Chilean Chemical Society

On-line version ISSN 0717-9707

Abstract

MATSUHIRO, BETTY; TORRES, SIMONET E  and  GUERRERO, JUAN. BLOCK STRUCTURE IN ALGINIC ACID FROM LESSONIA VADOSA (LAMINARIALES, PHAEOPHYTA). J. Chil. Chem. Soc. [online]. 2007, vol.52, n.1, pp.1095-1098. ISSN 0717-9707.  http://dx.doi.org/10.4067/S0717-97072007000100009.

Alkaline extraction of Lessonia vadosa blades collected in Fuerte Bulnes (southern Chile) afforded sodium alginate in 14.5% yield. Partial acid hydrolysis of the sodium alginate gave three fractions which were characterised by one- and two-dimensional nuclear magnetic resonance techniques. Fraction 1 (17.8 % yield) showed to be mainly composed of alternate heteropolymeric block (MG) and in minor proportions of polymannuronic sequences. Analysis of 13C NMR and 2D HSQC spectra indicated that Fraction 2 (64.5% yield) is a polymannuronic enriched fraction. The minor amount of guluronic acid residues in this fraction showed by 2D 1H/1H NOESY NMR spectrum to be present in a 1→4 homopolyguluronic sequence; moreover, the interresidue correlation data indicated that MG blocks were not present. Results are in agreement with data obtained by FT-IR spectroscopy in the solid state. Full assignments of 1H and 13C signals in the NMR spectra indicated that Fraction 3 (17.7%) presented a regular homopolyguluronic block structure

Keywords : seaweeds; alginic acid; block composition; Lessonia vadosa; NMR.

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