Polysaccharides from medicinal mushrooms and their antitumor activities - A review

Bioactive polysaccharides or their conjugates with protein are the best known mushroom substances derived from medicinal mushrooms that exhibit immunomodulating and antitumor properties. These antitumor compounds identified as β-glucans or proteoglycans are extracted from fruiting bodies, submerged cultural mycelial biomass or liquid culture broth have already entered the health care system in countries like Japan, China and USA. These substances are harmless to the body and do not add additional stress and therefore, are regarded as biological response modifiers. Their potential antitumor activity is due to their high molecular weight, solubility in water and triple helix high order structure that exhibit considerable structural variability. There are a handful of medicinally important such molecules that have achieved clinical relevance and acceptance. This review summarizes the current status of these antitumor polysaccharides, highlighting their chemical structure, the extraction and purification procedures, antitumor activity and cellular mechanisms.