Polysaccharide-K (Krestin, PSK) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
-bound
polysaccharide
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...
isolated from the fruitbody of ''
Trametes versicolor''.
Research summary
PSK has been studied in patients with gastric cancer, breast cancer, colorectal cancer, and lung cancer. The
US Food and Drug Administration has not approved PSK for cancer treatment or other medical uses. PSK has been the subject of investigation as an experimental
adjunctive therapy
Combination therapy or polytherapy is therapy that uses more than one medication or modality. Typically, the term refers to using multiple therapies to treat a ''single'' disease, and often all the therapies are pharmaceutical (although it can also ...
for various types of cancers in Japan; however, sufficient data to demonstrate its efficacy for such purposes is lacking.
Preliminary studies have examining PSK include use conjunction with
chemotherapy
Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...
for colorectal cancer,
non-small cell lung carcinoma,
breast cancer,
liver cancer,
and leukemia.
https://www.ncbi.nlm.nih.gov/pubmed/2220434
->
PSK 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
Medicinal fungi are fungi that contain metabolites or can be induced to produce metabolites through biotechnology to develop prescription drugs. Compounds successfully developed into drugs or under research include antibiotics, anti-cancer drugs, ...
References
{{Reflist, 2
External links
*American Cancer Society's page fo
''Trametes versicolor'' and Polysaccharide-K
*Memorial Sloan-Kettering Cancer Center's page fo
''Trametes versicolor'' and Polysaccharide-K
*
by the MD Anderson Cancer Center.
information from Drugs.com.
Medicinal fungi