Nowadays, parabens have been replaced by domiphen bromide, which is widely used in pharmaceutical and cosmetic products.
The main aim of this study was to investigate stressed degradation products of domiphen bromide by mean of a rapid, specific and reliable LC-ESI MS/MS since phenyl bromination may occur due to the oxidation of bromide counter ion under oxidative conditions. LC-ESI-MS/MS have characterized a new compound, p-bromodomiphen, as the only degradation product and structure elucidation was also confirmed by the synthesis of the standard. Notably, the resulting p-bromodomiphen bromide is more stable then domiphen bromide in oxidizing conditions since no di-bromoderivatives were detected by MS studies; both domiphen and its p-bromo derivative were tested for antibacterial activity and were more effective on Gram positive (Staphylococcus aureus ATCC25923 and Bacillus cereus DSM31) compared to Gram negative bacteria (Escherichia coli ATCC25922 and Pseudomonas aeruginosa DSM22644). In conclusion, stressed degradation studies by LC-ESI-MS/MS have characterized a new compound that comprises an alternative to domiphen bromide since its antimicrobial activity is comparable to, if not better than, the parental compound.