De Carvalho Bertozo Luiza, Morgon Nelson Henrique, De Souza Aguinaldo Robinson, Ximenes Valdecir Farias
Department of Chemistry, Faculty of Sciences, São Paulo State University (UNESP), Bauru 17033-360, Brazil.
Department of Chemistry, Institute of Chemistry, Campinas State University (UNICAMP), Campinas 13083-861, Brazil.
Biomolecules. 2016 Apr 21;6(2):23. doi: 10.3390/biom6020023.
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.
牛磺酸溴胺（Tau-NHBr）由次溴酸（HOBr）与氨基酸牛磺酸反应生成。Tau-NHBr作为一种用于局部的抗炎和杀菌药物，其应用越来越广泛。在此，我们对Tau-NHBr与内源性和非内源性化合物的化学反应性进行了全面研究。将Tau-NHBr的反应性与HOBr、次氯酸（HOCl）和牛磺酸氯胺（Tau-NHCl）进行了比较。得到了Tau-NHBr与色氨酸（7.7×10² M⁻¹s⁻¹）、褪黑素（7.3×10³ M⁻¹s⁻¹）、血清素（2.9×10³ M⁻¹s⁻¹）、丹磺酰甘氨酸（9.5×10¹ M⁻¹s⁻¹）、四甲基联苯胺（6.4×10² M⁻¹s⁻¹）和H₂O₂（3.9× M⁻¹s⁻¹）反应的二级速率常数（k₂）。Tau-NHBr在与游离氨基酸反应时表现出以下选择性：色氨酸＞半胱氨酸～甲硫氨酸＞酪氨酸。Tau-NHBr的反应性受介质pH值的强烈影响（例如与丹磺酰甘氨酸反应：pH 5.0时为1.1×10⁴ M⁻¹s⁻¹，pH 7.0时为9.5×10 M⁻¹s⁻¹，pH 9.0时为1.7×10 M⁻¹s⁻¹），这一特性与酸性pH条件下二溴胺形式（Tau-NBr₂）的形成有关。在Tau-NHBr与H₂O₂的反应中观察到单线态氧的形成。Tau-NHBr也能与亚油酸反应，但与HOBr和HOCl相比效率较低。与HOBr相比，Tau-NHBr不能与核苷反应。总之，建立了以下反应活性顺序：HOBr＞HOCl＞Tau-NHBr＞Tau-NHCl。这些发现对牛磺酸卤胺生物应用感兴趣的研究人员可能非常有帮助。
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