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4.4 Bioactive Carbohydrates from Animal Products
4.4.1 Heparan Sulfate/Heparin
Heparin and heparan sulfates are closely related linear anionic polysaccharides.
They belong to the group called glycosaminoglycans (GAGs), which exhibit several
important biological activities. These polysaccharides which exhibit poly- dispersity,
are synthesized in the Golgi apparatus of animal cells. Heparin that possesses highly
sulfated, linear structure are considered as an important member of glycosaminoglycans. It is composed of repeated units of sulfonated hexuronic acid (1 → 4)
D-glucosamine. Heparan sulfate is an extracellular glycosaminoglycan that is
widely distributed in membranes. However, heparin is found primarily intracellularly in the granules of mast cells.
Heparin has received a lot of scientific attention due to its anticoagulant activity
just as interest has increasingly grown to value the various roles that heparan sulfate
plays in normal and pathophysiology (Nikitovic et al. 2014). Activities of Heparin
and heparan sulfates include anticoagulation (Kamhi et al. 2013), signaling and
development (Zhang et al. 2014a), and infectious disease, inflammation, and cancer
(Garcia et al. 2014). Uronic acid residue in heparin which consists of α-l-iduronic
acid (IdoA) or β-d-glucuronic acid (GlcA) can be sulfated at the second oxygen
position. The residue of glucosamine can present unmodified (GlcN), N-sulfonated
(GlcNS), or N-acetylated (GlcNAc), with various O-sulfations at the third and sixth
oxygen positions (Fig. 4.9) (Nikitovic et al. 2014).
4.4.2 Hyaluronic Acid
The hyaluronic acid also called hyaluronan, is an anionic, non-sulfated glycosaminoglycan with high molecular weight. For instance, the human synovial HA averages about seven million Da per molecule, or about twenty thousand disaccharide
monomers (Cyphert et al. 2015). Hyaluronic acid is composed of alternating units
of D-glucuronic acid, and N-acetyl- D- glucosamine (Fig. 4.10). It exists naturally
in the body performing essential biological functions. It is the component of the
extracellular matrix (ECM) which explains why it is widely distributed in connective, epithelial, and neural tissues (Elmorsy et al. 2014).
Many studies have documented the chondroprotective effects of hyaluronic acid
(HA) in vivo and its influence on the articular cartilage. It was also documented that
exogenous HA could promote the synthesis of proteoglycan, modulate the functions
of immune cells, and reduce the activity of proinflammatory cytokines (Elmorsy
et al. 2014). Hyaluronic acid with special structure is also reasoned to be a prominent signalling molecule that can interact with cell surface receptors and thereby
modulate cell adhesion, migration, and proliferation (Lam et al. 2014).
T. A. Oyedepo and A. A. A. Kayode
4.4 Bioactive Carbohydrates from Animal Products
4.4.1 Heparan Sulfate/Heparin
Heparin and heparan sulfates are closely related linear anionic polysaccharides.
They belong to the group called glycosaminoglycans (GAGs), which exhibit several
important biological activities. These polysaccharides which exhibit poly- dispersity,
are synthesized in the Golgi apparatus of animal cells. Heparin that possesses highly
sulfated, linear structure are considered as an important member of glycosaminoglycans. It is composed of repeated units of sulfonated hexuronic acid (1 → 4)
D-glucosamine. Heparan sulfate is an extracellular glycosaminoglycan that is
widely distributed in membranes. However, heparin is found primarily intracellularly in the granules of mast cells.
Heparin has received a lot of scientific attention due to its anticoagulant activity
just as interest has increasingly grown to value the various roles that heparan sulfate
plays in normal and pathophysiology (Nikitovic et al. 2014). Activities of Heparin
and heparan sulfates include anticoagulation (Kamhi et al. 2013), signaling and
development (Zhang et al. 2014a), and infectious disease, inflammation, and cancer
(Garcia et al. 2014). Uronic acid residue in heparin which consists of α-l-iduronic
acid (IdoA) or β-d-glucuronic acid (GlcA) can be sulfated at the second oxygen
position. The residue of glucosamine can present unmodified (GlcN), N-sulfonated
(GlcNS), or N-acetylated (GlcNAc), with various O-sulfations at the third and sixth
oxygen positions (Fig. 4.9) (Nikitovic et al. 2014).
4.4.2 Hyaluronic Acid
The hyaluronic acid also called hyaluronan, is an anionic, non-sulfated glycosaminoglycan with high molecular weight. For instance, the human synovial HA averages about seven million Da per molecule, or about twenty thousand disaccharide
monomers (Cyphert et al. 2015). Hyaluronic acid is composed of alternating units
of D-glucuronic acid, and N-acetyl- D- glucosamine (Fig. 4.10). It exists naturally
in the body performing essential biological functions. It is the component of the
extracellular matrix (ECM) which explains why it is widely distributed in connective, epithelial, and neural tissues (Elmorsy et al. 2014).
Many studies have documented the chondroprotective effects of hyaluronic acid
(HA) in vivo and its influence on the articular cartilage. It was also documented that
exogenous HA could promote the synthesis of proteoglycan, modulate the functions
of immune cells, and reduce the activity of proinflammatory cytokines (Elmorsy
et al. 2014). Hyaluronic acid with special structure is also reasoned to be a prominent signalling molecule that can interact with cell surface receptors and thereby
modulate cell adhesion, migration, and proliferation (Lam et al. 2014).
T. A. Oyedepo and A. A. A. Kayode