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

Many studies have suggested an antioxidant role for taurine, but few studie s have directly measured its free radical scavenging activity. The aim of t he present study was to directly determine the action of taurine and taurin e analogs to inhibit peroxynitrite-mediated oxidation of dihydrorhodamine 1 23 (DHR) to rhodamine. Taurine was also tested to determine if it could att enuate the toxicity of sodium nitroprusside (SNP) to neuronal cultures. Tau rine at concentrations above 30mM had a modest ability to inhibit peroxynit rite 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) slig htly potentiated DHR oxidation by SIN-1, Short-term (1-hour) treatment of P C12 cultures with either SNP (1-2 mM) or taurine (20-40 mM) appeared to ind uce cellular proliferation. In contrast, 24-hour treatment with SNP (1mM) i nduced 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 o f peroxynitrite.