Selenium-Containing Compounds Protect DNA fromSingle-Strand Breaks Caused by Peroxynitrite

Peroxynitrite (ONOO−/ONOOH) is a powerful oxidant that can induce mutations and cause single-strand breaks in plasmid supercoiled DNA. The selenium-containing compound ebselen rapidly reacts with peroxynitrite. Therefore, ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one] and other selenium-containing molecules, selenomethionine and selenocystine, were studied as agents protecting DNA from single-strand breaks induced by peroxynitrite. Selenomethionine and selenocystine protected DNA from single-strand breaks more effectively than their sulfur analogs, methionine and cystine, and they also were more effective than glutathione or the hydroxyl radical scavenger mannitol. These results suggest that selenium-containing compounds can protect DNA from damage caused by peroxynitrite.