Pajares, María A.Zimmerman, TahlSánchez-Gómez, Francisco J.Ariza, AdrianaTorres, María J.Blanca, MiguelCañada, F. JavierMontañez, María I.Pérez-Sala, Dolores2022-04-202022-04-202020-03-04Pajares MA, Zimmerman T, Sánchez-Gómez FJ, Ariza A, Torres MJ, Blanca M, et al. Amoxicillin Inactivation by Thiol-Catalyzed Cyclization Reduces Protein Haptenation and Antibacterial Potency. Front Pharmacol. 2020 Mar 4;11:189http://hdl.handle.net/10668/3543Serum and cellular proteins are targets for the formation of adducts with the β-lactam antibiotic amoxicillin. This process could be important for the development of adverse, and in particular, allergic reactions to this antibiotic. In studies exploring protein haptenation by amoxicillin, we observed that reducing agents influenced the extent of amoxicillin-protein adducts formation. Consequently, we show that several thiol-containing compounds, including dithiothreitol, N-acetyl-L-cysteine, and glutathione, perform a nucleophilic attack on the amoxicillin molecule that is followed by an internal rearrangement leading to amoxicillin diketopiperazine, a known amoxicillin metabolite with residual activity. Increased diketopiperazine conversion is also observed with human serum albumin but not with L-cysteine, which mainly forms the amoxicilloyl amide. The effect of thiols is catalytic and can render complete amoxicillin conversion. Interestingly, this process is dependent on the presence of an amino group in the antibiotic lateral chain, as in amoxicillin and ampicillin. Furthermore, it does not occur for other β-lactam antibiotics, including cefaclor or benzylpenicillin. Biological consequences of thiol-mediated amoxicillin transformation are exemplified by a reduced bacteriostatic action and a lower capacity of thiol-treated amoxicillin to form protein adducts. Finally, modulation of the intracellular redox status through inhibition of glutathione synthesis influenced the extent of amoxicillin adduct formation with cellular proteins. These results open novel perspectives for the understanding of amoxicillin metabolism and actions, including the formation of adducts involved in allergic reactions.enAtribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/AmoxicillinB-lactam antibioticsInactivation mechanismRedox regulationProtein adductsThiol groupsThiol-containing moleculesBacterial growthAmoxicilinaBeta-lactamasCrecimiento bacterianoMedical Subject Headings::Chemicals and Drugs::Organic Chemicals::Sulfur Compounds::Amino Acids, Sulfur::Cysteine::AcetylcysteineMedical Subject Headings::Chemicals and Drugs::Organic Chemicals::Amides::Lactams::beta-Lactams::Penicillins::Penicillin G::Ampicillin::AmoxicillinMedical Subject Headings::Chemicals and Drugs::Organic Chemicals::Alcohols::Sugar Alcohols::DithiothreitolMedical Subject Headings::Chemicals and Drugs::Organic Chemicals::Amides::Lactams::beta-Lactams::Cephalosporins::Cephalexin::CefaclorMedical Subject Headings::Chemicals and Drugs::Organic Chemicals::Amides::Lactams::beta-LactamsMedical Subject Headings::Chemicals and Drugs::Chemical Actions and Uses::Specialty Uses of Chemicals::Laboratory Chemicals::Indicators and Reagents::Reducing AgentsMedical Subject Headings::Chemicals and Drugs::Chemical Actions and Uses::Pharmacologic Actions::Therapeutic Uses::Anti-Infective Agents::Anti-Bacterial AgentsMedical Subject Headings::Chemicals and Drugs::Heterocyclic Compounds::Heterocyclic Compounds, 1-Ring::Piperazines::DiketopiperazinesMedical Subject Headings::Diseases::Immune System Diseases::HypersensitivityMedical Subject Headings::Chemicals and Drugs::Amino Acids, Peptides, and Proteins::Peptides::Oligopeptides::GlutathioneMedical Subject Headings::Phenomena and Processes::Chemical Phenomena::Chemical Processes::Physicochemical Processes::Oxidation-Reductionresearch article32210804open access10.3389/fphar.2020.001891663-9812PMC7065267