Taurine Bromamine: Reactivity of an Endogenous and Exogenous Anti-Inflammatory and Antimicrobial Amino Acid Derivative

Abstract

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−1s−1), melatonin (7.3 × 103 M−1s−1), serotonin (2.9 × 103 M−1s−1), dansylglycine (9.5 × 101 M−1s−1), tetramethylbenzidine (6.4 × 102 M−1s−1) and H2O2 (3.9 × M−1s−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−1s−1, pH 7.0, 9.5 × 10 M−1s−1 and pH 9.0, 1.7 × 10 M−1s−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.

Electroceutical Treatment of Pseudomonas aeruginosa Biofilms

“…6) 26,42 . Taurine chloramines are produced when the amino acid taurine reacts with HOCl 43 . Such products can be produced from interaction between HOCl and bacteria 26,44 .…”

Swift Cure of a Chronic Wound Infected With Multiresistant Staphylococcus aureus in an Elderly Patient With Stage 5 Renal Disease

“…6,8,13 NCT in combination with NBrT cured a herpes zoster case with remarkably rapid reepithelialization. 14 Natural synthesis of these compounds by myeloperoxidase and eosinophil peroxidase 15 produce redox potential alterations 15 that apart from anti-inflammatory and antimicrobial activity 16 may influence redox control of tissue repair mechanisms. 17 In this case report, the combination of taurine derivatives provided a saving therapeutic solution for a life-threatening chronic wound infected with a multiresistant S aureus in a significantly weakened elderly patient with chronic renal failure.…”

Oxidative Alteration of Trp-214 and Lys-199 in Human Serum Albumin Increases Binding Affinity with Phenylbutazone: A Combined Experimental and Computational Investigation

“…In this case, the consumption of N acTyr was partially inhibited by 10-fold molar excess of methionine, and totally inhibited by cysteine ( Figure 1 b). N acTrp was also submitted to oxidation by Tau-NHCl, which is much less reactive than Tau-NBr 2 [ 32 ]. For this reason, the reactions were conducted for 1 h and the remaining amino acids were measured by HPLC.…”

“…This chemical feature of Tau-NBr 2 is related to its intermediate reactivity when compared to other strong and weak oxidizing agents of the same family, such as HOBr, HOCl, and Tau-NHCl. Indeed, a comparison of rate constants among these compounds and several biological targets provide the following general sequence: HOBr > HOCl > Tau-NBr 2 > Tau-NHCl [ 32 ]. Specifically, a comparison between HOCl and Tau-NBr 2 showed that, while the depletion of tryptophan residues in lysozyme was significantly higher using Tau-NBr 2 , the degradation of the protein, evidenced by its aggregation, was only observed using HOCl [ 41 ].…”