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Carbohydrate Research 333 (2001) 281 – 293
Structural studies on fucoidans from the brown seaweed
Sargassum stenophyllum
Maria E.R. Duarte,
a
Marc A. Cardoso,
a
Miguel D. Noseda,
a,1
Alberto S. Cerezo
b,2
*
a
Departamento de Bioquı ´mica, Uniersidade Federal do Parana ´ , PO Box 19046, CEP 81531 -990 Curitiba,
Parana ´ , Brazil
b
Departamento de Quı ´mica Orga ´nica, CIHIDECAR -CONICET, Facultad de Ciencias Exactas y Naturales,
Uniersidad de Buenos Aires, Ciudad Uniersitaria, Pabello ´n 2, 1428 Buenos Aires, Argentina
Received 20 November 2000; accepted 19 May 2001
Abstract
The brown seaweed Sargassum stenophyllum biosynthesizes two different sets of fucoidans. One of them is
characterized by higher percentages of glucuronic acid and fewer sulfate groups, which are situated on different sugar
units. -L-Fucose was the major component but other sugars like -D-galactose, -D-mannose, -D-glucuronic acid,
-D-glucose and -D-xylose were also in substantial amounts. Fucoidans from the other set contain small amounts
of -D-glucuronic acid and high percentages of sulfate groups, which are concentrated on the fucose residues, with
only fucose and galactose as major components. Structural studies of one fucoidan from each set suggest that these
products have a general basic structure that has a formal resemblance to that of the fucosylated chondroitin sulfates
from the body wall of sea cucumbers, namely, a linear core (formed mainly by (1 6)--D-galactose and/or
(1 2)--D-mannose units) with branched chains of ‘fucans’ (formed by (1 3) and/or (1 4)--L-fucose, (1 4)--
D-glucuronic acid, terminal -D-xylose and, sometimes, (1 4)--D-glucose). In fucoidans from the second set, the
‘core’ is reduced to short galactan chains. © 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Fucoidans; Fucans; Chemical structure; Sulfated heteropolysaccharides; Brown seaweed; Sargassum stenophyllum
1. Introduction
Brown seaweeds (Phaeophyceae) produce
families of sulfated fucoidans
†
among other
polysaccharides. They frequently contain
other sugars besides L-fucose, namely, D-xy-
lose, D-galactose and D-glucuronic acid; how-
ever, additional sugars, like D-mannose and
D-glucose, have also appeared.
In particular circumstances, either fucose or
galactose constitutes more than 95% of the
component monosaccharides, as in the ‘fucan’
of Fucus esiculosus
1
or the ‘-D-galactan sul-
fate’ from Laminaria angustata.
2
Several bio-
logical activities for these polysaccharides
have been examined,
1,3–8
but as the structure
of fucoidans has not been elucidated, the rela-
tionship between structure and biological
properties is far from being established. A
study of fucoidans from the brown seaweed
Sargassum stenophyllum, is reported herein.
* Corresponding author. Tel./fax: +54-11-45763346.
E -mail address: cerezo@qo.fcen.uba.ar (A.S. Cerezo).
1
Research member of the National Research Council of
Brazil (CNPq).
2
Research member of the National Research Council of
Argentina (CONICET).
†‘
Fucoidan’ will be used as a general term for all the
L-fucose-containing polysaccharides from brown seaweeds,
while ‘fucan’ will be reserved for the polysaccharides built up
mostly ( 95%) with L-fucose.
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