THE EFFECT OF HOMOCYSTEINE THIOLACTONE AND ITS ALPHA-ALKYLATED DERIVATIVE ON THE SURVIVAL OF IRRADIATED ESCHERICHIA-COLI AB1157

The radiation induced decomposition of homocysteine thiolactone (HCTL) and alpha-methyl-homocysteine thiolactone (alpha-MHCTL) was studied i n aqueous solution (pH = 5.4) as a function of dose (up to 1.55 kGy) i n the absence and presence of oxygen as well as in solutions saturated with N2O. The strongest radiolysis of both substances was observed in oxygenated solution, because of the peroxide transient formation. E. coli AB 1 157 were used as model of living systems for toxicity studie s of alpha-MHCTL in the range of 6 x 10(-9) to 6 x 10(-3) mol dm-3. Co mparative survival curves of E. coli bacteria using alpha-MHCTL, HCTL and cysteamine in the presence of air showed that alpha-MHCTL is the m ost efficient radiation protector. Rather high radiation protective ef fect on bacteria was also observed in absence of oxygen. The correspon ding D37 data (kGy) are reported.