The objective of this study was to investigate the activation of natural killer (NK) cells and anticancer effects of exo-biopolymer from rice bran cultured with Lentinus edodes [rice bran exo-biopolymer (RBEP)]. Oral administration of RBEP induced the activation of NK cells in a dose-dependent manner. RBEP also prolonged the life spans of mice transplanted with Sarcoma-180 cells and inhibited growing Sarcoma-180 cells in intraperitoneum. Solid tumor growth was also suppressed by oral administration of RBEP in C57/Bl6 mice transplanted with B16/Bl6 melanoma. Intraperitoneal injection of RBEP was more effective than oral administration at the same dosage in mice with transplanted tumor cells. According to this result, when RBEP directly contacts immune cells, the anticancer activity is higher than by indirectly inducing an immune response through oral administration. Therefore, we suggest that the administration of RBEP may be effective for preventing and/or treating cancer through NK cell activation. However, further studies are needed to elucidate the possible mechanisms of the anticancer activity and to investigate the other beneficial effects of RBEP for the development of a new biological response modifier.

Saengshik is a Korean noncooked food made with of more than 30 different whole gains, vegetables, fruits, mushrooms, and seaweeds. All of these ingredients are frozen and dried to minimize the loss of nutrients. Saengshik has become popular among health-conscious people in the Republic of Korea. The study aims to investigate antioxidant effects of Saengshik by in vivo and human experiments. In in vivo tests, mice were fed Saengshik for 4 weeks, and oxidative damage was induced by CCl(4). Then the effects of Saengshik on oxidative damage were examined. It was found that plasma lipid hydroperoxide and protein oxidative damages were significantly suppressed and antioxidants, glutathione, and thiol groups were increased. The activity of the antioxidant enzyme superoxide dismutase was increased, and the level of glutamate pyruvate transaminase was decreased. In a human study, elderly people were given Saengshik for 24 weeks, and changes in antioxidant defense of the body were examined. Antioxidant activities in plasma were enhanced, although the difference was not significant. Therefore, it is expected that Saengshik is effective at removing oxidants from body tissues, preventing oxidative damage, and eventually boosting the antioxidant capacity of the body.