Efficacy of taurine based compounds as hydroxyl radical scavengers in silica induced peroxidation

While it is widely believed that taurine may play an important role in protecting cells against toxic injury by functioning as an antioxidant, there is a lack of evidence to support this hypothesis. In this study, electron spin resonance (ESR) was used to investigate the reaction of taurine and hypotaurine with hydroxyl radicals (OH). The Fenton reaction (Fe(II) + H₂O₂ → Fe(III) + OH + OH^-) and the Cr(V)-mediated Fenton-like reaction (Cr(V) + H₂O₂ → Cr(VI) + OH = OH^-) were used as sources of OH radicals. The results show that hypotaurine but not taurine effectively scavenges OH radicals with a reaction rate constant of k = 1.6 x 10¹⁰ M^-1s^-. That is comparable with other efficient OH radical scavengers. The effect of taurine and hypotaurine on silica-induced lipid peroxidation was evaluated using linoleic acid as a model lipid. Hypotaurine, but not taurine, caused a significant inhibition of silica-induced lipid peroxidation. The results show that hypotaurine is an excellent anti-oxidant and appears to have the potential for being a therapeutic agent against silica-induced lung injury.