Abstract
In the present study, we examined in vivo radioprotection activity of Zn-, Mn-, Cu-, or Se-containing heat-treated Saccharomyces serevisiae yeast. The mineral-containing yeast powder was suspended in a 0.5% methyl cellulose solution. The suspension was administered i.p. to C3H mice before or after 7.5 Gy whole body X-irradiation. The 30-day survival of mice without injection of mineral yeast was about 7%. The survival of mice to which mineral-containing yeast was injected at 30 min before irradiation was 65-90%. The survival of mice was about 75%, when Se- or Mn-containing yeast was injected immediately after the irradiation, while it was more than 90% when Zn- or Cu-containing yeast was injected. Even the yeast containing no mineral showed significant radioprotection (70-80%). The Zn-containing yeast showed radioprotection when injected at 60 min post-irradiation (>80%) and even at 24 h post-irradiation (about 30%). The DRF of Zn-containing yeast (100 mg/kg, i.p. immediately after irradiation) was about 1.2. Bio-modulation is a possible mechanism for the radioprotection, since yeast without mineral is effective, it is effective for the radiation dose of bone marrow death, and it is effective for post-irradiation. In addition, other mechanisms may be involved since Zn- or Cu-containing yeast showed higher radioprotection than yeast without mineral.
