Taurine Bromamine: Reactivity of an Endogenous and Exogenous Anti-Inflammatory and Antimicrobial Amino Acid Derivative.
Taurine bromamine (Tau-NHBr) is produced by the reaction between hypobromous acid (HOBr) and the amino acid taurine. There are increasing number of applications of Tau-NHBr as an anti-inflammatory and microbicidal drug for topical usage. Here, we performed a comprehensive study of the chemical reactivity of Tau-NHBr with endogenous and non-endogenous compounds. Tau-NHBr reactivity was compared with HOBr, hypochlorous acid (HOCl) and taurine chloramine (Tau-NHCl). The second-order rate constants (k₂) for the reactions between Tau-NHBr and tryptophan (7.7 × 10² M(-1)s(-1)), melatonin (7.3 × 10³ M(-1)s(-1)), serotonin (2.9 × 10³ M(-1)s(-1)), dansylglycine (9.5 × 10¹ M(-1)s(-1)), tetramethylbenzidine (6.4 × 10² M(-1)s(-1)) and H₂O₂ (3.9 × M(-1)s(-1)) were obtained. Tau-NHBr demonstrated the following selectivity regarding its reactivity with free amino acids: tryptophan > cysteine ~ methionine > tyrosine. The reactivity of Tau-NHBr was strongly affected by the pH of the medium (for instance with dansylglycine: pH 5.0, 1.1 × 10⁴ M(-1)s(-1), pH 7.0, 9.5 × 10 M(-1)s(-1) and pH 9.0, 1.7 × 10 M(-1)s(-1)), a property that is related to the formation of the dibromamine form at acidic pH (Tau-NBr₂). The formation of singlet oxygen was observed in the reaction between Tau-NHBr and H₂O₂. Tau-NHBr was also able to react with linoleic acid, but with low efficiency compared with HOBr and HOCl. Compared with HOBr, Tau-NHBr was not able to react with nucleosides. In conclusion, the following reactivity sequence was established: HOBr > HOCl > Tau-NHBr > Tau-NHCl. These findings can be very helpful for researchers interested in biological applications of taurine haloamines.
Department of Chemistry, Faculty of Sciences, São Paulo State University (UNESP), Bauru 17033-360, Brazil. luiza_bertozo@yahoo.com.br.
Luiza
L
De Carvalho Bertozo
Department of Chemistry, Institute of Chemistry, Campinas State University (UNICAMP), Campinas 13083-861, Brazil. nhmorgon@gmail.commailto.
Nelson Henrique
NH
Morgon
Department of Chemistry, Faculty of Sciences, São Paulo State University (UNESP), Bauru 17033-360, Brazil. arobinso@fc.unesp.br.
Aguinaldo Robinson
AR
De Souza
Department of Chemistry, Faculty of Sciences, São Paulo State University (UNESP), Bauru 17033-360, Brazil. vfximenes@fc.unesp.br.
Valdecir Farias
VF
Ximenes
D000890:Anti-Infective Agents / Q000737:chemistry*; D000893:Anti-Inflammatory Agents / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D012709:Serum Albumin / Q000737:chemistry; D026082:Singlet Oxygen / Q000378:metabolism; D013654:Taurine / Q000031:analogs & derivatives* / Q000737:chemistry; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism
D000890:Anti-Infective Agents; D000893:Anti-Inflammatory Agents; D012709:Serum Albumin; D026082:Singlet Oxygen; D013654:Taurine; C052954:N-bromotaurine; D014364:Tryptophan
melatonin; nucleosides; serotonin; singlet oxygen; taurine bromamine; tryptophan