The effect of purified polysaccharides on immunostimulation and
cancer therapy
This Report has attempted to appraise, in particular but not exclusively, the
therapeutic functions of mushroom polysaccharides and polysaccharide-protein
complexes on animal and human systems. Amongst their many biopharmacological
activities the most intriguing are those associated with immunomodulatory and anticancer effects. In mushrooms, they occur mostly as glucans with different types of
glycosidic linkages such as (1-3), (1-6)-β-glucans and (1-3)-α-glucans, as true
heteroglucans, while others bind to protein residues as polysaccharide-protein
complexes.
Why then do these mushroom polysaccharides display such an array of
biopharmacological activities? Polysaccharides, unlike proteins and nucleic acids,
contain repetitive structural features that are polymers of monosaccharide residues
joined to each other by glycosidic linkage. Consequently, these polysaccharides
offer a high capacity for carrying biological information because of their increased
potential for structural variability. The amino acids in proteins and the nucleotides in
nucleic acids can only interconnect in one way while the monosaccharide units in the
polysaccharides can interconnect at several points to create a wide array of linear
and branched molecules. It has been calculated that the number of possible
permutations from four different sugar monosaccharides could be up to 35, 560
unique tetrasaccharides, whereas four amino acids can form only 24 different
permutations. This, then, creates a vast potential flexibility for the precise regulatory
mechanisms of various cell-cell interactions in higher organisms