The Interaction of Hypotaurine and Other Sulfinates with Reactive Oxygen and Nitrogen Species: A Survey of Reaction Mechanisms

Alessia Baseggio Conrado, Mila D'Angelantonio, Maria D'Erme, Laura Pecci, Mario Fontana (Lead / Corresponding author)

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    Considerable strides have been made in understanding the oxidative mechanisms involved in the final steps of the cysteine pathway leading to taurine. The oxidation of sulfinates, hypotaurine and cysteine sulfinic acid, to the respective sulfonates, taurine and cysteic acid, has never been associated with any specific enzyme. Conversely, there is strong evidence that in vivo formation of taurine and cysteic acid is the result of sulfinate interaction with a variety of biologically relevant oxidants. In the last decade, many experiments have been performed to understand whether peroxynitrite, nitrogen dioxide and carbonate radical anion could be included in the biologically relevant reactive species capable of oxidizing sulfinates. Thanks to this work, it has been possible to highlight two possible reaction mechanisms (direct and indirect reaction) of sulfinates with reactive oxygen and nitrogen species.The sulfinates oxidation, mediated by peroxynitrite, is an example of both reaction mechanisms: through a two-electron-direct-reaction with peroxynitrite or through a one-electron-indirect-transfer reaction. In the indirect mechanism, the peroxynitrite homolysis releases hydroxyl and nitrogen dioxide radical and in addition the degradation of short-lived adduct formed by peroxynitrite and CO2 can generate carbonate radical anion. The reaction of hypotaurine and cysteine sulfinic acid with peroxynitrite-derived radicals is accompanied by extensive oxygen uptake with the generation of transient intermediates, which can begin a reaction by an oxygen-dependent mechanism with the sulfonates, taurine, and cysteic acid as final products. Due to pulse radiolysis studies, it has been shown that transient sulfonyl radicals (RSO2(•)) have been produced during the oxidation of both sulfinates by one-electron transfer reaction.The purpose is to analyze all the aspects of the reactive mechanism in the sulfinic group oxidation of hypotaurine and cysteine sulfinic acid through the results obtained from our laboratory in recent years.

    Original languageEnglish
    Title of host publicationTaurine 10
    EditorsDong-Hee Lee, Stephen W. Schaffer, Eunkyue Park, Ha Won Kim
    Place of PublicationDordrecht
    Number of pages11
    ISBN (Electronic)9789402410792
    ISBN (Print)9789402410778
    Publication statusPublished - 2017
    Event20th International Taurine Meeting: “Taurine and Brain Health” - Plaza Hotel, Seoul, Korea, Republic of
    Duration: 23 May 201627 May 2016

    Publication series

    NameAdvances in Experimental Medicine and Biology
    ISSN (Print)0065-2598
    ISSN (Electronic)2214-8019


    Conference20th International Taurine Meeting
    Abbreviated titleINTAM20
    Country/TerritoryKorea, Republic of
    Internet address


    • Hypotaurine
    • Sulfonyl radicals
    • Reactive sulfur species
    • Carbonate anion radical
    • Sulfinates
    • Cysteine sulfinic acid


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