Cell Wall Polysaccharides of Marine Algae References 571
Part D | 22
tion [22.447]. Sulfated and longer fragments show
stronger antioxidant activities than nonsulfated and
shorter ones.
22.5.10 Chemical Modification
Sulfation (or oversulfation) of marine algal polysaccharides is an effective way of obtaining biologically active
derivatives that are especially interesting as potential
anticoagulants. The patterns of sulfation are often an
important factor of expected biological activity. The
inactive partially sulfated and 3,6-anhydro-substituted
Ä, Ã, and  -carrageenans have been oversulfated regioselectively, and the anticoagulant activity of the
derivatives obtained has been studied by aPTT in vitro
assay [22.471]. The results confirmed that sulfation at
O-2 of 3,6-anhydro-˛-D-Galp and at O-6 of ˇ-D-Galp
increases the anticoagulant activity. The oversulfated
Ä-carrageenan showed a 30 times higher anticoagulant
activity on doubling the PT time in comparison with
the native polysaccharide [22.472]. This derivate also
gave a threefold enhancement of the glutamic plasminogen (Glu-Plg) activation by tissue plasminogen activator (t-PA) or by urokinase (u-PA), while both native
Ä-carrageenan and crude heparin were less active. Similarly, oversulfated fucoidan showed four times higher
anticoagulant activity in doubling PT time and gave
higher stimulations of Glu-Plg activation by t-PA and
by u-PA in comparison to the native fucoidan [22.473].
Oversulfation of fucoidan also enhances its antiangiogenic and antitumor activities [22.474]. Similarly
what was mentioned above, oligomers of marine algal polysaccharides can be sulfated or oversulfated
as well. Alginate oligosaccharides obtained by treatment with alginate lyase from Vibrio sp. 510 [22.442]
have been sulfated by the formamide-chlorosulfonic
acid method [22.475]. One of the derivatives obtained
showed significant inhibition of tumor growth without direct cytotoxic effect, which was proposed to
be caused by immunomodulation. Oversulfated, acetylated, and phosphorylated derivatives of Ä-carrageenan
oligosaccharides have been prepared and their in vitro
antioxidant activities tested [22.476, 477]. In certain
antioxidant systems some of these derivatives exhibit
higher activities than the initial poly and oligosaccharides. The Ä-carrageenan oligosaccharide derivatives
inhibit tumor growth and stimulate macrophage phagocytosis and spleen lymphocyte proliferation [22.478].
Among them, the oversulfated derivative shows the
highest antitumor activity expressed both in the decrease of tumor weight and in eliciting NK cell activity.
These effects are significantly higher than those of the
unmodified oligosaccharides. There are two ways to
obtain novel materials based on marine algal polysaccharides: (i) covalent cross-linking via previously added
substituents and/or cross-linking agents (dialdehydes,
epichlorohydrin, phenolics, etc.), and (ii) interaction
with synthetic polymers or their fragments. Porous scaffolds based on alginate derivative bearing phenolics
has been prepared using horseradish peroxidase catalyzing cross-linkage formation between phenolic hydroxyls [22.479]. These materials have been shown to
be suitable for cell immobilization. Cross-linking carrageenan beads (microgels) have been prepared for controlled release delivery systems using epichlorohydrin
as the cross-linker [22.480]. The swelling/shrinking
behavior of these cross-linked microgels in saline solutions has shown great potential for the application
in food or pharmaceutical products. Highly stretchable and tough hydrogels have been prepared from
cross-linked algal polysaccharide and synthetic polymers [22.481]. Both types of macromolecules form
networks based on ionic (alginate) and covalent (polyacrylamide) cross-linkages. Because they contain
90% water, composite gels can be stretched beyond
20 times their initial length, and notched samples
exhibit a stretch of 17 times. These novel material
containing marine algal polysaccharides (cross-linked
alginate) significantly enlarge the area of hydrogel
applications.
References
22.1
Z.A. Popper, G. Michel, C. Hervé, D.S. Domozych,
W.G.T. Willats, M.G. Tuohy, B. Kloareg, D.B. Stengel: Evolution and diversity of plant cell walls:
From algae to flowering plants, Annu. Rev. Plant
Biol. 62, 567–590 (2011)
22.2
D. S. Domozych: Algal cell walls, DOI: 10.1002/
9780470015902.a0000315.pub3, eLC, Wiley Online
Libary (2011)
22.3
D.S. Domozych, M. Ciancia, J.U. Fangel,
M.D. Mikkelsen, P. Ulvskov, W.G.T. Willats:
The cell walls of green algae: A journey through
evolution and diversity, Front. Plant Sci. 3, 1–7
(2012)
22.4
M. Guibet, P. Boulenguer, J. Mazoyer, N. Kervarec,
A. Antonopoulos, M. Lafosse, W. Helbert: Composition and distribution of carrabiose moieties
Part D | 22
tion [22.447]. Sulfated and longer fragments show
stronger antioxidant activities than nonsulfated and
shorter ones.
22.5.10 Chemical Modification
Sulfation (or oversulfation) of marine algal polysaccharides is an effective way of obtaining biologically active
derivatives that are especially interesting as potential
anticoagulants. The patterns of sulfation are often an
important factor of expected biological activity. The
inactive partially sulfated and 3,6-anhydro-substituted
Ä, Ã, and  -carrageenans have been oversulfated regioselectively, and the anticoagulant activity of the
derivatives obtained has been studied by aPTT in vitro
assay [22.471]. The results confirmed that sulfation at
O-2 of 3,6-anhydro-˛-D-Galp and at O-6 of ˇ-D-Galp
increases the anticoagulant activity. The oversulfated
Ä-carrageenan showed a 30 times higher anticoagulant
activity on doubling the PT time in comparison with
the native polysaccharide [22.472]. This derivate also
gave a threefold enhancement of the glutamic plasminogen (Glu-Plg) activation by tissue plasminogen activator (t-PA) or by urokinase (u-PA), while both native
Ä-carrageenan and crude heparin were less active. Similarly, oversulfated fucoidan showed four times higher
anticoagulant activity in doubling PT time and gave
higher stimulations of Glu-Plg activation by t-PA and
by u-PA in comparison to the native fucoidan [22.473].
Oversulfation of fucoidan also enhances its antiangiogenic and antitumor activities [22.474]. Similarly
what was mentioned above, oligomers of marine algal polysaccharides can be sulfated or oversulfated
as well. Alginate oligosaccharides obtained by treatment with alginate lyase from Vibrio sp. 510 [22.442]
have been sulfated by the formamide-chlorosulfonic
acid method [22.475]. One of the derivatives obtained
showed significant inhibition of tumor growth without direct cytotoxic effect, which was proposed to
be caused by immunomodulation. Oversulfated, acetylated, and phosphorylated derivatives of Ä-carrageenan
oligosaccharides have been prepared and their in vitro
antioxidant activities tested [22.476, 477]. In certain
antioxidant systems some of these derivatives exhibit
higher activities than the initial poly and oligosaccharides. The Ä-carrageenan oligosaccharide derivatives
inhibit tumor growth and stimulate macrophage phagocytosis and spleen lymphocyte proliferation [22.478].
Among them, the oversulfated derivative shows the
highest antitumor activity expressed both in the decrease of tumor weight and in eliciting NK cell activity.
These effects are significantly higher than those of the
unmodified oligosaccharides. There are two ways to
obtain novel materials based on marine algal polysaccharides: (i) covalent cross-linking via previously added
substituents and/or cross-linking agents (dialdehydes,
epichlorohydrin, phenolics, etc.), and (ii) interaction
with synthetic polymers or their fragments. Porous scaffolds based on alginate derivative bearing phenolics
has been prepared using horseradish peroxidase catalyzing cross-linkage formation between phenolic hydroxyls [22.479]. These materials have been shown to
be suitable for cell immobilization. Cross-linking carrageenan beads (microgels) have been prepared for controlled release delivery systems using epichlorohydrin
as the cross-linker [22.480]. The swelling/shrinking
behavior of these cross-linked microgels in saline solutions has shown great potential for the application
in food or pharmaceutical products. Highly stretchable and tough hydrogels have been prepared from
cross-linked algal polysaccharide and synthetic polymers [22.481]. Both types of macromolecules form
networks based on ionic (alginate) and covalent (polyacrylamide) cross-linkages. Because they contain
90% water, composite gels can be stretched beyond
20 times their initial length, and notched samples
exhibit a stretch of 17 times. These novel material
containing marine algal polysaccharides (cross-linked
alginate) significantly enlarge the area of hydrogel
applications.
References
22.1
Z.A. Popper, G. Michel, C. Hervé, D.S. Domozych,
W.G.T. Willats, M.G. Tuohy, B. Kloareg, D.B. Stengel: Evolution and diversity of plant cell walls:
From algae to flowering plants, Annu. Rev. Plant
Biol. 62, 567–590 (2011)
22.2
D. S. Domozych: Algal cell walls, DOI: 10.1002/
9780470015902.a0000315.pub3, eLC, Wiley Online
Libary (2011)
22.3
D.S. Domozych, M. Ciancia, J.U. Fangel,
M.D. Mikkelsen, P. Ulvskov, W.G.T. Willats:
The cell walls of green algae: A journey through
evolution and diversity, Front. Plant Sci. 3, 1–7
(2012)
22.4
M. Guibet, P. Boulenguer, J. Mazoyer, N. Kervarec,
A. Antonopoulos, M. Lafosse, W. Helbert: Composition and distribution of carrabiose moieties