The edible mushroom Ganoderma lucidum (G. lucidum), popularly known as Lingzhi in China and Reishi or Mannentake in Japan, belongs to the Fungi kingdom, order Polyporales and family Ganodermataceae. Due to its intrinsic immunomodulatory and antitumor properties, it has been widely used
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for the general promotion of health and longevity in Asian countries. During the Ming Dynasty, this basidiomycete was known as “the mushroom of immortality” and/or “the marvelous herb”, and it was used as a tonic to cure several human diseases, such as hepatopathy, hypertension, nephritis, bronchitis, and cancer (Sliva et al., 2002; 2003; Zhang et al., 2002; Chan et al., 2005; Lin, 2005). In the Imperial Court of ancient China, its dried powder was especially popular as a cancer chemotherapeutic agent (Mizushina et al., 1998). Nowadays, G. lucidum is commercialized in a powdered form, as a medicinal beverage, as well as a nutraceutical food.
Most of the different compounds, with several biological activities, extracted from the mycelia, fruiting bodies or spores are associated with antitumor effects (Chiu et al., 2000). One of the first scientific reports on antitumor effects of G. ganoderma was published by Maruyama et al. (1989), who observed that aqueous but not ethanolic extract of this mushroom was remarkably effective at inhibiting the subcutaneous growth of murine sarcoma 180. This effect was mainly attributed to a carbohydrate-rich fraction obtained by ion-exchange chromatography, and produced the highest effect when the animals were inoculated intraperitoneally.
Extracts obtained from powdered spores and fruiting bodies can inhibit the active transcription factors AP-1 enzyme and NF-kB in breast and prostate cancer cells, by inhibiting the expression of urokinase-type plasminogen activator (uPA) and its receptor. In fact, increased levels of urokinase expression were shown to be associated with malignancy and it was observed that inhibition of this enzyme suppresses metastasis of breast and prostate cancer cells (Sliva et al., 2002). Ingestion of 1.5 g/day of a water-soluble extract, obtained from mycelia grown in liquid culture medium, is able to significantly diminish the colorectal adenomas of patients after 12 months of treatment (Oka et al., 2010).
Zhuang et al. (2009) reported that patients with different types of cancer, under chemotherapy and/or radiotherapy, who ingested a dietary complex with G. reishi for 6 weeks showed decreases of leukopenia and neutropenia, as well as a delay in the decrease of NK-cell and CD4 lymphocyte counts. The maintenance of NK cells by the dietary complex was attributed to the activity of the G. lucidum polysaccharides. However, the fact that this complex was prepared with many other phytotherapeutic species precludes any conclusion that the final effect was due to Ganoderma.
Among the compounds showing pharmacological and immunomodulatory properties, special attention has been directed to polysaccharides and triterpenes.