Attenuation of oxidation and nitration reactions of peroxynitrite by selenomethionine, selenocystine and ebselen.

The effect of the selenium-containing compounds selenomethionine, selenocystine and ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one] on the oxidation of dihydrorhodamine 123 caused by peroxynitrite and on the nitration of 4-hydroxyphenylacetate by peroxynitrite was studied in comparison with their sulphur analogues methionine, cystine and ebsulfur [2-phenyl-1,2-benzisothiazol-3(2H)-one]. The selenocompounds protected dihydrorhodamine 123 from oxidation and 4-hydroxyphenylacetate from nitration more effectively than their sulphur analogues. Sodium selenite exhibited no effect. These observations are corollaries to the recent finding [Roussyn, Briviba, Masumoto and Sies (1996) Arch. Biochem. Biophys. 330, 216-218] that selenium-containing compounds are efficient in protecting against peroxynitrite-induced DNA single-strand breaks.