Metalloantibiotic Mn(II)-bacitracin complex mimicking manganese superoxide dismutase

Chanin Nantasenamat, Department of Clinical Microbiology, Faculty of Medical Technology, Mahidol University
Chartchalerm Isarankura-Na-Ayudhya, Department of Clinical Microbiology, Faculty of Medical Technology, Mahidol University
Theeraphon Piacham, Department of Clinical Microbiology, Faculty of Medical Technology, Mahidol University
Sakda Yainoy, Department of Clinical Microbiology, Faculty of Medical Technology, Mahidol University
Lei Ye, Pure and Applied Biochemistry, Chemical Center, Lund University
Leif Bülow, Pure and Applied Biochemistry, Chemical Center, Lund University
Virapong Prachayasittikul, Department of Clinical Microbiology, Faculty of Medical Technology, Mahidol University

Abstract

Superoxide dismutase (SOD) activities of various metallobacitracin complexes were evaluated using the riboflavin-methionine-nitro blue tetrazolium assay. The radical scavenging activity of various metallobacitracin complexes was shown to be higher than those of the negative controls, e.g., free transition metal ions and metal-free bacitracin. The SOD activity of the complex was found to be in the order of Mn(II) > Cu(II) > Co(II) > Ni(II). Furthermore, the effect of bacitracin and their complexation to metals on various microorganisms was assessed by antibiotic susceptibility testing. Moreover, molecular modeling and quantum chemical calculation of the metallobacitracin complex was performed to evaluate the correlation of electrostatic charge of transition metal ions on the SOD activity. © 2006 Elsevier Inc. All rights reserved.