Abstract

Gamma-irradiated exo-polysaccharide can be obtained from submerged exo-polysaccharide from Grifola frondosa extracts. The low molecular exo-polysaccharide is obtained by irradiation showed potential anti-oxidant activity and then those effect showed synergic anti-tumor activity on adriamycin. Exo-polysaccharide modified by 10 kGy dose of irradiation showed strong radical scavenging activity by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) reduction assay. The 50% rate inhibited the DPPH reduction concentration of gamma irradiated exo-polysaccharide were 350µg/ml. Gamma irradiated exo-polysaccharide showed stronger inhibitory effect on tumor growth of L1210 leukemia to compare with non-irradiated exo-polysaccharide at the same dose of 21 mg/kg. Modified exo-polysaccharide by irradiation reduced the tert-butylhydro peroxide (tBuOOH) induced cytotoxicity in various leukemic cell lines. In leukemic mouse model using L1210, the combination between adriamycin and gamma irradiated exo-polysaccharide decreased to about 60% compared to the treatment of adriamycin alone. These results indicate that gamma irradiated exo-polysaccharide has radical scavenging activity and prevents an oxidative stress and inhibit tumor growth by leukemia; therefore, gamma irradiated exo-polysaccharide is suggested as a food supplement having anti-oxidant properties exhibiting potent synergic effect against anti-leukemia in this study.

Key words: Gamma irradiated exo-polysaccharide, anti-oxidant, oxidative stress, anti-tumor activity.