56
3 Chitin
cancer has been widely studied and is still presently undergoing studies. Mechanisms
reported include increasing the activities of enzymes which inhibit cancer cells or
kill them, boosting the body’s own immune response to cancerous cells, inhibiting of
certain enzymes required for cancer cell growth or altering the pathways for cancer
cell proliferation such as interfering with DNA replication. Chitin and chitosan could
also act against cancer by accumulating within the cancer cells and partaking in
reactions which result in production of toxins which eventually lead to the cancer
cell death. The activity of chitin, chitosan and their derivatives vary from preventing
cancer cells from forming, inhibiting the growth of existing cancer cells or preventing
the metastasis (spreading) of the cancer to other parts of the body thereby making
treatment more manageable.
The effectiveness of chitin and chitosan in their various applications has been
shown to be significantly affected by factors such as molecular weight and the degree
of deacetylation. In fact, one study showed that oligomers of chitosan, which are
short-chain chitosan of molecular weight between 1.5 and 5.5 kDa, had more effective
antitumor activity against sarcoma than higher molecular weight chitosan and low
molecular weight chitosan indicating a specific range of molecular weight required
(You-Jin and Kim 2002). Therefore, processing techniques such as gel permeation
chromatography to separate into different molecular weights, achieving a higher
degree of deacetylation during production and higher purity using methods such
as ultrafiltration, becomes important for optimum effectiveness particularly when
considering the high-end application such as antitumor and tissue repair application
of these biopolymers. Such processing is what adds additional processing costs as
the value of the chitin increases from crude chitin to chitosan with low degree of
deacetylation and polydisperse to more monodisperse chitosan with high degree of
polymerization. The quality criteria for chitin and chitosan are mainly molecular
weight, degree of deacetylation, purity and polydispersity. The values for each of
these will depend on the intended application.
3.7.7 Anti-inflammatory
Chitosan has been shown to have some anti-inflammatory properties. Inflammations are generally caused by inflammatory cytokines released by the immune cells
such as macrophages. In certain inflammatory diseases, things get out of hand,
there is excessive production of inflammatory cytokines and these result in pain
and discomfort.
Other than the antimicrobial property which also induces anti-inflammatory effect
by destroying the inflammatory disease-causing bacteria, chitosan has been shown
to have direct anti-inflammatory effect. The mechanism by which this happens is
by inhibiting inflammatory cytokine production in the presence of inflammationinducing microbes. For example in the presence of chitosan-alginate nanoparticles,
the inflammatory activity of the acne causing bacteria P. acnes which induces the production of inflammatory cytokines by the immune cells was inhibited (Friedman et al.
3 Chitin
cancer has been widely studied and is still presently undergoing studies. Mechanisms
reported include increasing the activities of enzymes which inhibit cancer cells or
kill them, boosting the body’s own immune response to cancerous cells, inhibiting of
certain enzymes required for cancer cell growth or altering the pathways for cancer
cell proliferation such as interfering with DNA replication. Chitin and chitosan could
also act against cancer by accumulating within the cancer cells and partaking in
reactions which result in production of toxins which eventually lead to the cancer
cell death. The activity of chitin, chitosan and their derivatives vary from preventing
cancer cells from forming, inhibiting the growth of existing cancer cells or preventing
the metastasis (spreading) of the cancer to other parts of the body thereby making
treatment more manageable.
The effectiveness of chitin and chitosan in their various applications has been
shown to be significantly affected by factors such as molecular weight and the degree
of deacetylation. In fact, one study showed that oligomers of chitosan, which are
short-chain chitosan of molecular weight between 1.5 and 5.5 kDa, had more effective
antitumor activity against sarcoma than higher molecular weight chitosan and low
molecular weight chitosan indicating a specific range of molecular weight required
(You-Jin and Kim 2002). Therefore, processing techniques such as gel permeation
chromatography to separate into different molecular weights, achieving a higher
degree of deacetylation during production and higher purity using methods such
as ultrafiltration, becomes important for optimum effectiveness particularly when
considering the high-end application such as antitumor and tissue repair application
of these biopolymers. Such processing is what adds additional processing costs as
the value of the chitin increases from crude chitin to chitosan with low degree of
deacetylation and polydisperse to more monodisperse chitosan with high degree of
polymerization. The quality criteria for chitin and chitosan are mainly molecular
weight, degree of deacetylation, purity and polydispersity. The values for each of
these will depend on the intended application.
3.7.7 Anti-inflammatory
Chitosan has been shown to have some anti-inflammatory properties. Inflammations are generally caused by inflammatory cytokines released by the immune cells
such as macrophages. In certain inflammatory diseases, things get out of hand,
there is excessive production of inflammatory cytokines and these result in pain
and discomfort.
Other than the antimicrobial property which also induces anti-inflammatory effect
by destroying the inflammatory disease-causing bacteria, chitosan has been shown
to have direct anti-inflammatory effect. The mechanism by which this happens is
by inhibiting inflammatory cytokine production in the presence of inflammationinducing microbes. For example in the presence of chitosan-alginate nanoparticles,
the inflammatory activity of the acne causing bacteria P. acnes which induces the production of inflammatory cytokines by the immune cells was inhibited (Friedman et al.