Block structure in alginic acid from lessonia vadosa (laminariales, phaeophyta)
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[1] Universidad de Santiago de Chile
Universidad de Santiago de Chile
Santiago, Chile
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- Localización: Journal of the Chilean Chemical Society (Boletín de la Sociedad Chilena de Química), ISSN-e 0717-6309, ISSN 0366-1644, Vol. 52, Nº. 1, 2007, págs. 1095-1098
- Idioma: inglés
- Enlaces
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Resumen
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
