Polysaccharopeptide (PSP) is a substance produced by an edible mushroom, Coriolus versicolor which has been claimed to possess antitumor activity. However, neither tumoricidal activity nor cytotoxicity was observed when five tumor cell lines and mouse peritoneal macrophages were cultured in vitro in the presence of 2.5-10 ?g/ml PSP. An increase in the production of reactive nitrogen intermediates, reactive oxygen intermediates (superoxide anions) and tumor necrosis factor was measured in peritoneal macrophages collected from inbred C57 mice which had received PSP in the drinking water for 2 weeks. Northern blot analysis also demonstrated that PSP activated the transcription of tumor necrosis factor gene in these cells, indicating that PSP exerted an immunomodulatory effect on the defensive cells.
Mushrooms are known for their nutritional and medicinal value (Breene, 1990) and also for the diversity of bioactive compounds they contain. The mushroom Coriolus versicolor (Yun Zhi) was recorded in the Compendium of Materia Medica by Li Shi Zhen during the Ming Dynasty in China, as being beneficial to health and able to bring longevity if consumed regularly. Various products derived from this mushroom and claimed to have medicinal value are commercially available. Among them, PSK (Sakagami et al., 1991) and PSP are the most prominent. It is the intent of this article to summarize research data pertaining to PSP.
PSK (Sakagami et al., 1991) and PSP are two chemically related products of the mushroom Coriolus versico~or isolated from deeplayer cultivated mycelia of the COV-1 and CM-101 strains, by Chinese and Japanese investigators, respectively. The similarities and differences of the two products have been pointed out by the Fungi Research Institute (1993a). Both possess a molecular weight of approximately 100 kDa and their polypeptide moieties are rich in aspartic acid and glutamic acid. Monosaccharides with o~-1,4 and [3-1,3 glucosidic linkages constitute the pol~saccharide moieties of PSP and PSK: fucose is found in the latter¢ whereas arabinose and rhamnose occur in the former. Both PSP and PSK have been found to be immunoenhancing and effective against tumor cells.
Effects of the immunomodulator PSK on the metabolism of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) to 5-fluorouracil (5-FU) were examined in 10 patients with advanced gastric cancer and who had undergone curative resection. PSK is a protein-bound preparation, extracted from Coriolus versicolor and belongs to Basidiomycetes. The 5-FU concentration in the plasma was 0.024 micrograms/ml at 15 min after the intravenous injection of 400 mg of tegafur and the area under the curve of 5-FU was 0.58 micrograms.h/ml. Following administration of PSK, 3 g/day for 8-14 months, there was no change in the plasma level of 5-FU, in any patient. As the clinical dose of PSK had no apparent influence on the metabolism of tegafur to 5-FU, the combination of PSK and tegafur can be prescribed to treat patients with advanced gastric cancer.
What Hartford Hospital in Conneticut has to say about Coriolus Versicolor
“Currently, extracts of Coriolus versicolor called polysaccharide-K (PSK) and polysaccharopeptide (PSP) are under study as immune stimulants for use alongside chemotherapy in the treatment of cancer. These two related substances, made from slightly different strains of the fungus, are thought to act as “biological response modifiers,” meaning that they affect the body’s response to cancer.
According to most but not all reported trials, most of which were performed in Asia, both PSK and PSP can enhance the effects of various forms of standard cancer treatment. For example, in a 28-day double-blind , placebo-controlled study of 34 people with advanced non–small-cell lung cancer, use of Coriolus extracts along with conventional treatment significantly slowed the progression of the disease.
It is thought that Coriolus extracts work by stimulating the body’s own cancer-fighting cells. PSK and PSP may also have cancer-preventive effects.
In addition, very weak evidence hints that extracts of Coriolus versicolor might be helpful for HIV infection.”