Beta-glucan compounds produced by Maitake (Grifola frondosa), a Japanese medicinal and culinary mushroom have multiple well-documented immunostimulatory properties. In recent years, the mushroom has generated considerable interest as a potential adjunct in cancer care. 

Now, a team of Portuguese & Argentine researchers have shown that a protein-bound polysaccaride within the mushroom, called the D-fraction, can trigger apoptosis in human breast cancer cell lines, indicating a direct anti-tumor effcct.

Dr. Raquel Soares and colleagues at the University of Porto, and Dr. Gabriela Balogh and her team at the Cerzos-Conicet, Bahia Blanca, Argentina, studied the effect of 5 different concentrations of the purified D-fraction in human MCF7 breast cancer cell cultures.

The D-fraction induced cell death in a dose-dependent manner, and at the highest concentrations (367 micrograms per mL), the apoptosis process was rapid and widespread within the treated cultures. Microarray analysis showed that the mushroom compound induced a marked 25-fold upregulation of BAK-1, a gene known to play a key role in the apoptotic cascade (Soares R, et al. J Medicinal Food. 2011: 20(10): 1-10).

While many earlier studies have shown that Maitake D-fraction can stimulate cell-mediated immune responses to various types of tumor tissue, this is the first evidence of a direct cytotoxic effect in human breast cancer cells. The researchers are planning a human trial to test D-fraction as an adjunct to chemotherapy in women with breast cancer.

The D-fraction compound is produced by a company called Mushroom Wisdom (formerly Maitake Products).