Tumor-specific cytocidal and immunopotentiating effects of relatively low molecular weight products derived from the basidiomycete, Agaricus blazei Murill.

Currently, some natural herbal extracts are believed to have a marked tumoricidal effect and low toxicity for normal tissues. We investigated the effect of relatively low molecular weight products extracted from the basidiomycete, Agaricus blazei Murill, on MethA tumor cell growth with the aim of producing synthetic derivatives based on these products. Inoculation of the low molecule fraction (LM) into the primary tumor of a two-tumor model resulted in the marked inhibition of the tumor, not only in the right flank, but also in the non-injected left flank. Chromatographic purification and physicochemical characterization showed the main tumoricidal activity to be located in a low molecule fraction-3 (LM-3), containing alpha-1,4-glucan-beta-1,6-glucan complex with an average molecular weight of 20 kDa. A11 LM fractions and crude ATF showed in vitro selective cytotoxicity for MethA tumor cells, having no effect on normal cells. Serum levels of immunosuppressive acidic protein (IAP) in mice receiving LM fractions, particularly LM-3, significantly increased, indicating the possible activation of granulocytes. We speculate that the inhibition of the distant tumor might be due to the increased migration of granulocytes, enhanced by the effect of extract injections at the primary tumor site.