45
The biological activity of mushroom polysaccharides differs among species and
is dependent on the length as well as the branching of the chain, chain rigidity, and
helical conformation (Ahmad et al. 2012). These activities have been attributed to
the (1 → 3)-β-glucan and (1 → 3), (1 → 6)-β-glucan, with the most positive effect
on immune stimulation obtained with (1 → 3)-β-glucan (Villares et al. 2012).
Mushroom polysaccharides that have demonstrated therapeutic effect against
human cancers include lentinan from shiitake, active hexose correlated compound
(AHCC) also from shiitake, schizophyllan from splitgill, maitake D-fraction from
Grifola frondosa and polysaccharide-K or polysaccharide P (PSK/PSP) from
Trametes versicolor (Friedman 2016). PSP and PSK have been reported to be nontoxic with prolonged use during the treatment of cancers. They suppress DNA/RNA
synthesis in the cancer cells and also enhance the immune function (Wang et al.
2019a, b). The glucan portion of PSK consists of a β-1-4 main chain and β-1-3 side
chains, with β-1-6 side chains that bind to a polypeptide moiety through O- or
N-glycosidic bonds. PSK has a molecular weight of approximately 100,000 Dalton.
This molecular weight of PSK has a great influence on their biological activities as
β-glucan with high molecular weight have stronger biological activities compared
to those with low molecular weight (Liu et al. 2015).
PSP is also a proteoglycan with a molecular weight of approximately100,000
Dalton which contains a polysaccharide and polypeptide portion (Wang et al. 2015).
It is used widely as an immune modifier and it is famous for its immunoregulatory,
anticancer, anti-inflammatory and antiviral activities (Chen and Huang 2018). The
polysaccharide component in PSP consists of monosaccharides with α-1,4 and
β-1,3 glucosidic linkages. PSP and PSK are chemically similar such that it may be
difficult to distinguish them. However, PSK contains fucose in its structure while
PSP has rhamnose and arabinose in its structure.
4.3 Bioactive Carbohydrates from Higher Plants
Polysaccharides obtained from plant sources constitute a large family of biopolymers which forms part of herbal ingredients that are widely used in many Asian
countries (Guo and Cui 2014). Several bioactive polysaccharides extracted and
separated from such plants have attracted a lot of research interest that examines
their biological activities (Xie et al. 2016b).
4.3.1 Beta-Glucans
Beta-glucans (β-Glucans) are naturally occurring polysaccharides comprising a
group of β-D-glucose polysaccharides naturally occurring in cell walls of cereals,
bacteria, and fungi. The structure of β- glucan is similar to that of cellulose except
that the β-(1 → 3)- linkages introduce a twist to the chain. This twist in the chain
4 Bioactive Carbohydrates, Biological Activities, and Sources
The biological activity of mushroom polysaccharides differs among species and
is dependent on the length as well as the branching of the chain, chain rigidity, and
helical conformation (Ahmad et al. 2012). These activities have been attributed to
the (1 → 3)-β-glucan and (1 → 3), (1 → 6)-β-glucan, with the most positive effect
on immune stimulation obtained with (1 → 3)-β-glucan (Villares et al. 2012).
Mushroom polysaccharides that have demonstrated therapeutic effect against
human cancers include lentinan from shiitake, active hexose correlated compound
(AHCC) also from shiitake, schizophyllan from splitgill, maitake D-fraction from
Grifola frondosa and polysaccharide-K or polysaccharide P (PSK/PSP) from
Trametes versicolor (Friedman 2016). PSP and PSK have been reported to be nontoxic with prolonged use during the treatment of cancers. They suppress DNA/RNA
synthesis in the cancer cells and also enhance the immune function (Wang et al.
2019a, b). The glucan portion of PSK consists of a β-1-4 main chain and β-1-3 side
chains, with β-1-6 side chains that bind to a polypeptide moiety through O- or
N-glycosidic bonds. PSK has a molecular weight of approximately 100,000 Dalton.
This molecular weight of PSK has a great influence on their biological activities as
β-glucan with high molecular weight have stronger biological activities compared
to those with low molecular weight (Liu et al. 2015).
PSP is also a proteoglycan with a molecular weight of approximately100,000
Dalton which contains a polysaccharide and polypeptide portion (Wang et al. 2015).
It is used widely as an immune modifier and it is famous for its immunoregulatory,
anticancer, anti-inflammatory and antiviral activities (Chen and Huang 2018). The
polysaccharide component in PSP consists of monosaccharides with α-1,4 and
β-1,3 glucosidic linkages. PSP and PSK are chemically similar such that it may be
difficult to distinguish them. However, PSK contains fucose in its structure while
PSP has rhamnose and arabinose in its structure.
4.3 Bioactive Carbohydrates from Higher Plants
Polysaccharides obtained from plant sources constitute a large family of biopolymers which forms part of herbal ingredients that are widely used in many Asian
countries (Guo and Cui 2014). Several bioactive polysaccharides extracted and
separated from such plants have attracted a lot of research interest that examines
their biological activities (Xie et al. 2016b).
4.3.1 Beta-Glucans
Beta-glucans (β-Glucans) are naturally occurring polysaccharides comprising a
group of β-D-glucose polysaccharides naturally occurring in cell walls of cereals,
bacteria, and fungi. The structure of β- glucan is similar to that of cellulose except
that the β-(1 → 3)- linkages introduce a twist to the chain. This twist in the chain
4 Bioactive Carbohydrates, Biological Activities, and Sources