Orally administered β-1,6-D-polyglucose extracted from Agaricus blazei results in tumor regression in tumor-bearing mice

There is an increasing demand from both patients and practicing oncologists for orally formulated chemotherapy. The present study focused on the oral formulation for natural products that may tie effectively used in oncologic treatment regimens. Tumor-bearing mice treated with intratumoral administration of aqueous ammonium oxalate-soluble and ethanol-insoluble derivatives of Agaricus blazei showed marked tumor regression at doses ranging from 0.1 to 2.5 mg (p < 0.05 vs. saline control; n = 7). However, oral administration of this same fraction, either prior to, simultaneously with, or after, tumor cell inoculation did not result in tumor regression (p > 0.05 vs. control). When this fraction was treated with hydrochloric acid (acid-treated fraction; ATF), intratumoral administration resulted in a marked regression of tumor growth comparable to that of the acid-untreated. fraction. More importantly, parenteral administration of ATF resulted in a significantly greater regression of tumor growth than that produced by the untreated fraction (p < 0.05 vs. untreated: n = 7). When a total of 4.5 mg of ATF was given orally at varying schedules prior to, simultaneously with, or after, tumor inoculation, a significant regression was seen using a schedule starting 4 days prior to inoculation (p < 0.05 vs, all other treatments: n = 7), NMR and molecular analyses showed that the ATF fraction had a molcular weight of approximately 10 kDa and consisted mainly of only (1,6)-beta-D-polyglucose. These results suggest that the oral administration of simple acid-treated ATF results in a remarkable tumor regression. Thus, simple acid hydrolysis of natural products may not only bring measurable benefits in oncological practice, but may also be a useful general formulation for natural products for oral chemotherapy.