Thiourea and Dimethylthiourea Inhibit Peroxynitrite-Dependent Damage: Nonspecificity as Hydroxyl Radical Scavengers

Thiourea and, more recently, dimethylthiourea, have been used as hydroxyl radical (OHradical dot) scavengers in experiments both in vitro and in vivo. We show that both compounds can inhibit nitration of the amino acid tyrosine on addition of peroxynitrite, and also the inactivation of α1-antiproteinase by peroxynitrite. Hence, protective effects of (dimethyl) thiourea could be due to inhibition of peroxynitrite-dependent damage as well as to OHradical dot scavenging, and these compounds must not be regarded as specific OHradical dot scavengers. © 1997 Elsevier Science Inc.