62
Since polysaccharides can regulate the function of macrophages, they can also
increase the host immune defense. Studies on the functions of macrophages have
demonstrated that glycans can enhance their functions and this includes the activation of phagocytic ability (Niu et al. 2017), increased cytotoxic activity against
tumour cells, reactive oxygen species (ROS) and nitric oxide (NO) production. It
also includes secretion of cytokines and chemokines, such as tumour necrosis factor
(TNF-α), interleukin-1β (IL-1β), IL-6, IL-12 and many more (Rabinovich and
Toscano 2009). For example, a study by Udani et al. (2009) documented that a polysaccharide from the cones of Juniperus scopulorum showed significant immunomodulatory effect to the murine macrophages. The study certified that the
polysaccharide caused an increased expression of macrophage iNOS and NO. Also,
there was enhanced secretion of cytokines such asIL-1, IL-6, IL-12, IL-10
and TNF-α.
The immunostimulating properties of mushrooms have been documented in
many Eastern countries (Friedman 2016). The bioactive polysaccharides in mushrooms are β-glucans. These substances also increase the host immune defense by
enhancing the function of macrophages and natural killer cells (Friedman 2016).
The mechanism for induction of cellular responses by β-glucans may be due to their
specific interaction with several cell surface receptors like complement receptor 3
(CR3; CD11b/CD18), lactosylceramide, selected scavenger receptors, and dectin-1.
β-Glucans are also known to demonstrate anticarcinogenic activities. They can prevent oncogenesis through their protection against potent genotoxic carcinogens
(Novak and Vetvicka 2008).
Anti-angiogenesis is a possible pathway by which β-glucans can decrease tumor
proliferation and prevent tumor metastasis. β-Glucan can, therefore, a supportive
therapy to cancer chemotherapy and radiotherapy as demonstrated by their positive
role in the restoration of hematopiesis followed by bone marrow injury (MorenoMendieta et al. 2017). Immunotherapy using monoclonal antibodies is a novel
strategy for cancer treatment. These antibodies trigger the activity of complement
system and alter tumor cells with iC3b fragment. It is difficult for tumor cells as
well as other host cells to trigger complement receptor 3-dependent cellular cytotoxicity and initiate tumor-killing activity because they do not have β-glucan as a
surface component. This mechanism will, therefore, be elicited only in the presence
of β-glucans (Carvalho et al. 2016).
4.7.4 Antitumor Activities
Malignant neoplasm is a dreaded disease that is very harmful to human health. Most
antitumor chemicals kill cancer cells but at the same time, they seriously damage
normal cells (Chen et al. 2014). This has led to numerous studies seeking alternative
cancer therapy. A good number of polysaccharides have strong antitumor activities
with broad application prospects. The ability of bioactive polysaccharides that have
structures containing a β-1,3 1,4 or 1,6 has been extensively demonstrated to
T. A. Oyedepo and A. A. A. Kayode
Since polysaccharides can regulate the function of macrophages, they can also
increase the host immune defense. Studies on the functions of macrophages have
demonstrated that glycans can enhance their functions and this includes the activation of phagocytic ability (Niu et al. 2017), increased cytotoxic activity against
tumour cells, reactive oxygen species (ROS) and nitric oxide (NO) production. It
also includes secretion of cytokines and chemokines, such as tumour necrosis factor
(TNF-α), interleukin-1β (IL-1β), IL-6, IL-12 and many more (Rabinovich and
Toscano 2009). For example, a study by Udani et al. (2009) documented that a polysaccharide from the cones of Juniperus scopulorum showed significant immunomodulatory effect to the murine macrophages. The study certified that the
polysaccharide caused an increased expression of macrophage iNOS and NO. Also,
there was enhanced secretion of cytokines such asIL-1, IL-6, IL-12, IL-10
and TNF-α.
The immunostimulating properties of mushrooms have been documented in
many Eastern countries (Friedman 2016). The bioactive polysaccharides in mushrooms are β-glucans. These substances also increase the host immune defense by
enhancing the function of macrophages and natural killer cells (Friedman 2016).
The mechanism for induction of cellular responses by β-glucans may be due to their
specific interaction with several cell surface receptors like complement receptor 3
(CR3; CD11b/CD18), lactosylceramide, selected scavenger receptors, and dectin-1.
β-Glucans are also known to demonstrate anticarcinogenic activities. They can prevent oncogenesis through their protection against potent genotoxic carcinogens
(Novak and Vetvicka 2008).
Anti-angiogenesis is a possible pathway by which β-glucans can decrease tumor
proliferation and prevent tumor metastasis. β-Glucan can, therefore, a supportive
therapy to cancer chemotherapy and radiotherapy as demonstrated by their positive
role in the restoration of hematopiesis followed by bone marrow injury (MorenoMendieta et al. 2017). Immunotherapy using monoclonal antibodies is a novel
strategy for cancer treatment. These antibodies trigger the activity of complement
system and alter tumor cells with iC3b fragment. It is difficult for tumor cells as
well as other host cells to trigger complement receptor 3-dependent cellular cytotoxicity and initiate tumor-killing activity because they do not have β-glucan as a
surface component. This mechanism will, therefore, be elicited only in the presence
of β-glucans (Carvalho et al. 2016).
4.7.4 Antitumor Activities
Malignant neoplasm is a dreaded disease that is very harmful to human health. Most
antitumor chemicals kill cancer cells but at the same time, they seriously damage
normal cells (Chen et al. 2014). This has led to numerous studies seeking alternative
cancer therapy. A good number of polysaccharides have strong antitumor activities
with broad application prospects. The ability of bioactive polysaccharides that have
structures containing a β-1,3 1,4 or 1,6 has been extensively demonstrated to
T. A. Oyedepo and A. A. A. Kayode