Studies on Antioxidant Effects of Culinary-Medicinal Bunashimeji Mushroom Hypsizygus marmoreus (Peck) Bigel. (Agaricomycetideae)

Abstract

The antioxidant effects of Hypsizygus marmoreus were investigated for peroxyl and alkoxyl radicals by ordinary, non-tumor-bearing and tumor-bearing mice. Antioxidant activity (AOA) was determined using the plasma of these mice. On one hand, the aqueous extract of H. marmoreus fruit body was found to have slight radical trapping activity for both peroxyl and alkoxyl radicals in vitro. On the other hand, when the blood plasma of mice, fed with fodder containing 5−10% of dried powders of mushroom extract, AOA was significantly augmented with aloxyl radicals. Using an HPLC post column AOA method, it was suggested that the increase of AOA in mice plasma was caused by an induction of high-molecular-weight components of the plasma, which were produced by feeding with H. marmoreus. Moreover, the amount of lipoperoxide in the mice plasma was measured as a value of thiobarbituric acid reactive substances. The in vivo effect of the intake of H. marmoreus fruit body was also investigated by plasma AOA status of tumor-bearing mice. Female DBA/2 mice, injected subcutaneously with 3-methylcholanthrene (MC), were fed for 76 weeks. It was found that the AOA of the mice with tumors was significantly higher than those of the mice without tumors. The high levels of AOA of the mice plasma were attributable to the increase of high-molecular-weight AOA components. Thus, oral administration of the fruit body of H. marmoreus exhibited potent antitumor or cancer-preventive effects and caused a significant decrease in lipid peroxide levels, which were determined as thiobarbituric acid reactive substances. These results showed that the intake of H. marmoreus fruit body could induce an antioxidant effect, and the increase of AOA in the plasma of tumor-bearing mice was an important mechanism in cancer prevention. It was also suggested that the mushroom might play a role in the decrease of lipid peroxides trough AOA induction.