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

Author(s)

Bertozo, Luiza De Carvalho ^[1] ; Morgon, Nelson Henrique ^[2] ; De Souza, Aguinaldo Robinson ^[1] ; Ximenes, Valdecir Farias ^[1]

Affiliation

^[1] Sao Paulo State Univ UNESP, Fac Sci, Dept Chem, BR-17033360 Bauru - Brazil

^[2] Campinas State Univ UNICAMP, Inst Chem, Dept Chem, BR-13083861 Campinas, SP - Brazil

• Document type: Journal article
• Source: BIOMOLECULES; v. 6, n. 2 JUN 2016.
• Web of Science Citations: 4

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 (k(2)) for the reactions between Tau-NHBr and tryptophan (7.7 x 10(2) M(-1)s(-1)), melatonin (7.3 x 10(3) M(-1)s(-1)), serotonin (2.9 x 10(3) M(-1)s(-1)), dansylglycine (9.5 x 10(1) M(-1)s(-1)), tetramethylbenzidine (6.4 x 10(2) M(-1)s(-1)) and H2O2 (3.9 x M(-1)s(-1)) were obtained. Tau-NHBr demonstrated the following selectivity regarding its reactivity with free amino acids: tryptophan > cysteine similar to 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 x 10(4) M(-1)s(-1), pH 7.0, 9.5 x 10 M(-1)s(-1) and pH 9.0, 1.7 x 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. (AU)

• FAPESP's process: 13/08784-0 - Kinetic studies of reactions mediated by oxidants produced by neutrophils: mechanism of deleterious action and development of enzyme inhibitors
• Grantee: Valdecir Farias Ximenes
• Support Opportunities: Regular Research Grants