Antitumor activity of rice-shochu post-distillation slurry and vinegar produced from the post-distillation slurry via oral administration in a mouse model.

Shochu is a Japanese spirit that is mainly produced in the Kyushu region. Rice-shochu post-distillation slurry (i.e. RSDS) is eluted during the conventional rice-shochu production process. Since RSDS contains several functional components, we have produced vinegar from RSDS. This study reports the antitumor activity of RSDS and the vinegar via oral administration in a mouse model. Freeze-dried RSDS (0.1 - 1.5%) or vinegar (0.3 - 1.5%) was mixed into a chemically defined diet. The tumor size and life span of tumor-bearing mice that were fed the diet were investigated for 72 d. The RSDS- (> 0.3%) or vinegar- (> 0.5%) fed mice had significantly smaller sized tumors than the control group (p < 0.01). We also found that those mice had prolonged life spans. Oral administration of RSDS or vinegar also prolonged the life spans of mice that were implanted with Colon 38 cells. These results indicated that dietary RSDS and vinegar suppressed tumor growth. Moreover, we found that NK cytotoxic activity against K562 cells was stimulated by RSDS and vinegar.