title: Multiple Roles of Cu(II) in Catalyzing Hydrolysis and Oxidation of β-Lactam Antibiotics.
abstract: The widely used β-lactam antibiotics such as penicillins and cephalosporins are known to be susceptible to CuII-catalyzed hydrolysis at their four-membered β-lactam ring. However, this study elucidates that CuIIcan in fact play multiple roles in promoting the hydrolysis and/or oxidation of β-lactam antibiotics under environmental aquatic conditions (pH 5.0-9.0 and 22 °C), depending on β-lactams' structural characteristics and solution pH. Most significantly, the β-lactam antibiotics that contain a phenylglycine primary amine group on the side chain can undergo direct oxidation by CuIIvia this functional group. On the other hand, the β-lactam ring of penicillins is susceptible to CuII-catalyzed hydrolysis, followed by oxidation of the hydrolysis product by CuII. In contrast, the β-lactam ring of cephalosporins is susceptible to CuII-catalyzed hydrolysis only. Solution pH influences the CuII-promoted transformation by affecting the β-lactam and CuIIcomplexation through protonation/deprotonation of critical organic functional groups. When CuIIacts as an oxidant to promote the transformation of β-lactam antibiotics to yield CuI, the overall role of CuIIappears catalytic if the reaction occurs under ambient atmospheric condition, due to quick oxidation of CuIby oxygen to regenerate CuII. Compared to earlier literature that largely assumed only the hydrolytic catalyst role of CuIIin promoting degradation of β-lactam antibiotics, the oxidative roles of CuIIidentified by this study mark important contributions to a more accurate mechanistic understanding.
authors.affiliation: School of Environmental Science and Engineering, Suzhou University of Science and Technology , Suzhou 215001, P. R. China.|School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|College of Environmental Science and Engineering, Tongji University , Shanghai, 200092, P. R. China.
authors.forename: Jiabin
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Peizhe
authors.initials: P
authors.lastname: Sun
authors.affiliation: College of Environmental Science and Engineering, Tongji University , Shanghai, 200092, P. R. China.
authors.forename: Yalei
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Ching-Hua
authors.initials: CH
authors.lastname: Huang
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002511:Cephalosporins; D006868:Hydrolysis; D010084:Oxidation-Reduction; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D047090:beta-Lactams