In vitro reactions of hypotaurine

Hypotaurine and cysteine sulfinic acid are natural sulfinates found in relatively low amounts in some mammalian tissues5. They are metabolic intermediates in the biosynthetic pathways leading to the corresponding sulfonates. The function of hypotaurine as a biological antioxidant in protecting some cells from oxidative damage, by scavenging free radical forms of oxygen, has been proposed in the past3, 9 and recently demonstrated in vitro.1, 4 Chemically, sulfinates are not very stable compounds; oxidation is the most important but not the only reaction they are involved in. The low content of natural sulfinates in physiological tissues or fluids makes it often necessary, to perform quantitative determinations, to submit the biological samples to enrichment procedures which could give rise to artefactual results. The presence of an acidic milieu was supposed to slow down the oxidation of hypotaurine to taurine, which is enhanced at alkaline pH. However, it seems that oxidation is also facilitated in the presence of deproteinizing acids such as sulfosalycilic acid3 or trichloroacetic acid.