Other Common Names:: Hua gu, Lentinan edodes
The cultivation of L. edodes (shiitake) first began in China about AD 1100. It is believed that shiitake cultivation techniques developed in China were introduced to the Japanese by Chinese growers.
Various species of trees have been used for the cultivation of shiitake. One of the primary species used in one area of Japan in past years was the shii tree--thus the derivation of the name shii-take. Most production today, however, is on various species of oak.
Medicinal properties have been attributed to mushrooms for thousands of years. Mushroom extracts are widely sold as nutritional supplements and touted as beneficial for health.
Shiitake is one of the best known and best characterized mushrooms used for medicinal purposes. Several medicinal properties have been attributed to shiitake in recent years. These properties include antitumor polysaccharides activity and glycoproteins, antiviral nucleic acids, platelet agglutination inhibitive substances, and anti-cholesterol active substances.
Lentinan, which is the name given a highly purified polysaccharide fraction extracted from Shiitake mushrooms, is an approved drug in Japan. It is generally administered by injection and has been used as an agent to prolong survival of patients in conventional cancer therapy as well as in AIDS research. Lentinan is commercially available for clinical use. Lentinan is not only useful for cancer treatment, but may also prevent the increase of chromasomal damage induced by anti-cancer drugs. Additionally, Shiitake contains all eight essential amino acids in better proportions than soy beans, meat, milk, or eggs as well as a good blend of vitamins and minerals including vitamins A, B, B12, C, D and Niacin.
In the last three decades, numerous polysaccharides and polysaccharide-protein complexes have been isolated from mushrooms and used as a source of therapeutic agents. The most promising biopharmacological activities of these biopolymers are their immunomodulation and anti-cancer effects. Three antitumor mushroom polysaccharides, have become large market items in Japan.
Although the mechansim of their antitumor action is still not completely clear, these polysaccharides and polysaccharide-protein complexes are suggested to enhance cell-mediated immune responses in vivo and in vitro and act as biological response modifiers. Potentiation of the host defense system may result in the activation of many kinds of immune cells that are vitally important for the maintenance of homeostasis. Polysaccharides or polysaccharide-protein complexes are considered as multi-cytokine inducers that are able to induce gene expression of vaious immunomodulatory cytokines and cytokine receptors. Some interesting studies focus on investigation of the relationship between their structure and antitumor activity, elucidation of their antitumor mechanism at the molecular level, and improvement of their various biological activities by chemical modifications.