Polysaccharide-K
Polysaccharide-K (Krestin, PSK) is a protein-bound polysaccharide isolated from the mycelium of Trametes versicolor.

Research
PSK is one of the most commonly used medicinal mushroom extracts with a long history as an additive in cancer therapy in Asia, especially in Japan. PSK has a documented anti-tumor activity both in vitro and in vitro, in various types of cancers, including colorectal, gastric, breast, liver, pancreatic, and lung cancer.

Monte Fisher, Li-Xi Yang 2002

Preliminary studies examining PSK include its use in conjunction with chemotherapy for colorectal cancer, non-small cell lung carcinoma, breast cancer, liver cancer, and leukemia.

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. 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.

See also

Medicinal mushrooms
Polysaccharide peptide

References

External links
American Cancer Society's page for Trametes versicolor and Polysaccharide-K.
Memorial Sloan-Kettering Cancer Center's page for Trametes versicolor and Polysaccharide-K.
A "Detailed Scientific Review of Trametes versicolor and Polysaccharide-K" by the MD Anderson Cancer Center.
Trametes versicolor and Polysaccharide-K information from Drugs.com.

Medicinal fungi