Chelating radioprotection of metallic ions or free radicals acceptors against Escherichia coli K12s inactivation by Technetium-99m

The Auger electron emitting radionuclide technetium-99m 99m Tc) is widely used in diagnostic nuclear medicine and to label different cellular and molecular structures for biomedical research. 99m Tc decays to the ground state predominantly by gamma ray emission and this process results in the emission of monoenergetic electrons (as internal conversion, Auger). The contact between this radionuclide and cells can produce many kinds of lesions in the cells, as chromosomal aberration, cell division inhibition and damage 99m Tc-labeled human lymphocyte, these effects can be due to reactive oxygen species (ROS) that are potentially able to cause biological damage. Previous studies indicate the participation of transition metals, such Fe (II), acting as reducing agents in the formation of hydroxyl radical (OH deg C), the most reactive ROS, through the Fenton reaction in bacterial cells. The simultaneous treatment with sodium benzoate or thiourea confers cell partial protection against the lethal effects of 99m Tc, indicating that OH as the main damaging agent. (author)