1. Introduction

Epidemiological data indicate that Asian people have lower rates of certain cancers, including cancers of the breast, prostate, and colon, as well as a lower incidence of cardiovascular disease, osteoporosis and postmenopausal symptoms. The fact that the traditional Asian diet is rich in soybean and its products containing isoflavones, is thought to be the reason for the health advantage of Asian people. Isoflavones are found in nature in a glycosylated form as a minor constituent of soybeans and other leguminous plants. While glycosides seem to be hard to absorb, aglycones are apparently better absorbed. The isoflavone glycosides are probably hydrolyzed in part by gastric acid and undergo enzymatic hydrolysis with β-glucosidase produced by intestinal microflora. Isoflavone aglycones are abundant in fermented soy products such as miso, natto and tempeh due to the hydrolysis during fermentation by β-glucosidase produced by Saccharomyces rouxii for miso and Bacillus natto for natto, respectively. The basidiomycetes mushrooms have been useful in folk medicine and useful against cancer due to their polysaccharides such as β-glucan, which reportedly enhances immune response. Some basidiomycetes mushrooms are known to produce β-glucosidase. It has been thought that during fermentation, basidiomycetes produce β-glucosidase enzymes which in turn converts isoflavone glycosides into glucose and genistein aglycones.

Angiogenesis, the formation of new capillaries from preexisting blood vessels, is a fundamental process involved in embryonic development and in pathological conditions such as tumorogenesis, diabetic retinopathy, and wound healing. Tumor growth is dependent on the angiogenesis process and requires new vessel growth. Recently, intake of soybean isoflavones, especially genistein which is in an aglycone, has reportedly played a role in the prevention of hormone related cancers. Genistein has also been reported to inhibit angiogenesis in vitro and in vivo, tumor cell proliferation, and in vivo tumor growth.

Apoptosis is a genetically regulated form of cell death which permits the safe disposal of cells at the point when they have fulfilled their intended biological function. Genistein has been reported to induce apoptosis and topoisomerase II-mediated DNA breakage. It is expected that the combination of genistein and basidiomycetes polysaccharides will be useful for cancer treatment and other related diseases due to their anti-angiogenic and anti-tumor activities respectively.