Polysaccharide-K
Protein-bound polysaccharide
From Wikipedia, the free encyclopedia
Polysaccharide-K (Krestin, PSK) is a protein-bound polysaccharide isolated from the mycelium[1][2] of Trametes versicolor.

Although PSK is approved in Japan as an adjuvant therapy in cancer treatment,[3] it is not approved in the United States for treatment of cancer or any clinical condition.[4]
Research
Chemistry
PSK is a protein polysaccharide consisting of a beta-glucan β-1,4 main chain with β-1,3 and β-1,6 side chains. The approximate molecular weight of PSK is 100,000 Da, and the protein component is reported at the β-1,6 side chain.[5] PSK is isolated from the "CM-101" strain of Trametes versicolor. The analogous compound PSP, is derived from the "COV-1" strain of Trametes versicolor.[6]