Polisaccharides from Cystocarpic Plants of the Red Seaweed Callophyllis Variegata

E. R. Merino; A. S. Cerezo; M. C. Matulewicz

doi:10.3390/50300551

,

and

Departamento de Química Orgánica, CIHIDECAR-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina

^*

Author to whom correspondence should be addressed.

Molecules2000, 5(3), 551-552;https://doi.org/10.3390/50300551

Version Notes

Order Reprints

Abstract

The crude polysaccharide from cystocarpic Callophyllis variegata was fractionated with potassium chloride yielding three minor fractions which precipitated between 0.05-0.10 M KCl, 1.20-1.25 M KCl and 1.80-2.00 M KCl, and a main product soluble in 2.00 M KCl. These fractions were analysed and structural analysis of the major one was carried out by methylation, FT-IR and ¹³C NMR.

Introduction

Callophyllis variegata belongs to the family Kallymeniaceae and there are only two previous studies [,] on seaweeds from the same genus, Callophyllis rhynchocarpa and Callophyllis hombroniana. These studies report the isolation of carrageenan-type polysaccharides.

Experimental

The crude polysaccharide and the fractions were analyzed using the methods mentioned in ref. []. The fraction soluble in 2.00 M KCl was converted into the corresponding triethylammonium salt and was methylated by the Hakomori procedure as described in ref. []. The samples were subjected to reductive hydrolysis and further acetylation, and were analyzed by GC []. The d:l-galactose ratio was determined by the method of ref. [].

Results and discussion

Cystocarpic plants of Callophyllis variegata, collected in Puerto Deseado (Provincia de Santa Cruz), were extracted with water at room temperature and the crude product was analyzed (carbohy-drate content, sulphate, primary sulphate and protein; composition in monosaccharides, d:l-galactose ratio). These analyses showed a molar ratio Gal:3,6-AnGal:sulfate of 1.00:0.24:0.56 and the absence of l-galactose suggesting the presence of a carrageenan. The usual way to fractionate a system of car-rageenans is based on the solubility of the component polysaccharides in solutions of different potas-sium chloride concentration; the preparative fractionation yielded three fractions which precipitated between 0.05-0.10 M KCl, 1.20-1.25 M KCl and 1.80-2.00 M KCl, and a main product soluble in 2.00 M KCl. These fractions were analyzed as described for the crude polysaccharide. Chemical analysis of the soluble fraction gave a molar ratio Gal:3,6-AnGal:sulfate of 1.00:0.16:1.47 and a d-:l-galactose ratio of 5.5:1.0. The structural analysis (methylation, FT-IR and ¹³C NMR) of this fraction will be reported.

Acknowledgements

This work was supported by grants from CONICET (PIA N° 6714) and the University of Buenos Aires (TW83).

References and Nores

Usov, A. I.; Ivanova, E. G.; Shashkov, A. S. Botanica Marina 1983, 26, 285.
Falshaw, R.; Furneaux, R. H.; Stevenson, D. E. Abstracts of the XVIth International Seaweed Symposium. 1998; 43. [Google Scholar]
Ciancia, M.; Matulewicz, M. C.; Cerezo, A. S. Phytochemistry 1997, 45, 1009.
Cases, M. R.; Cerezo, A. S.; Stortz, C. A. Carbohydrate Research 1995, 269, 333–341.