Taurine is a weak scavenger of peroxynitrite and does not attenuate sodium nitroprusside toxicity to cells in culture

Many studies have suggested an antioxidant role for taurine, but few studies have directly measured its free radical scavenging activity. The aim of the present study was to directly determine the action of taurine and taurine analogs to inhibit peroxynitrite-mediated oxidation of dihydrorhodamine 123 (DHR) to rhodamine. Taurine was also tested to determine if it could attenuate the toxicity of sodium nitroprusside (SNP) to neuronal cultures. Taurine at concentrations above 30mM had a modest ability to inhibit peroxynitrite formation derived from SIN-1. Hypotaurine could inhibit peroxynitrite formation from both SIN-1 (down arrow 75%) and SNP (down arrow 50%) at 10mM, Other taurine analogs (homotaurine, beta -alanine & isethionic acid) slightly potentiated DHR oxidation by SIN-1, Short-term (1-hour) treatment of PC12 cultures with either SNP (1-2 mM) or taurine (20-40 mM) appeared to induce cellular proliferation. In contrast, 24-hour treatment with SNP (1mM) induced cell death. Combination treatments with taurine and SNP appeared to interact in an additive fashion for both cell proliferation and neurotoxic actions. It appears unlikely that taurine is a major endogenous scavenger of peroxynitrite.