2014 Volume 63 Issue 1 Pages 1-12
We examined the protective efficacy of Japanese sake against ionizing X-irradiation and biologically analysed sake for radioprotective compounds. The sake used in this experiment is Junmai-shu (ethanol content, 10.5%) that made only from rice and malted rice. Male C57BL/6JJms mice aged 9 weeks were orally administered 0.6mL sake/mouse within 30min of 7.8Gy whole body irradiation or 0.2mL sake daily for one week prior to and after irradiation control mice received either Futsu‐shu(ethanol content, 15%), pure ethanol(10.5%) or saline. Futsu-shu is made from rice and malted rice with alcohol added. To test the effect of X-ray-induced lethality in mice, we observed short-term survival(30days) rates in the mice after exposure. Mice administered Junmai-shu demonstrated significantly increased survival rate compared with saline(p‹0.01). The survival rates were greatest for the Junmai-shu group followed by the Futsu-shu, ethanol and saline groups. Radioprotection was not solely a result of hydroxyl radical scavenging by ethanol because pure ethanol demonstrated lower protective effect than sake. Sake contains a greater variety and quantity of amino acids than most other alcoholic drinks. Junmai-shu had a much higher amino acid content than Futsu-shu(1771mg/L vs. 932mg/L), suggesting one possible source of radioprotection. Our results reveal that pure ethanol was slightly protective against lethality but to a lesser degree than sake. A high content of amino acids in sake is one of the unique features of sake that provides a radioprotective effect.