BLOCK STRUCTURE IN ALGINIC ACID FROM LESSONIA VADOSA (LAMINARIALES, PHAEOPHYTA)
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...
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| Autores principales: | , , |
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| Lenguaje: | English |
| Publicado: |
Sociedad Chilena de Química
2007
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072007000100009 |
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| Sumario: | 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 |
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