Synthesis of moxifloxacin–Au (III) and Ag (I) metal complexes and their biological activities

The drug-metal complexes are used to control the growth of pathogens and parasites which are harmful to humans. Moxifloxacin (MOX) is a new fourth generation 8- methoxy fluoroquinolone. Its chemical name is [1-cyclopropyl-7-(S,S)-2,8-diazabicyclo(4.3.0)- non-8-yl-6-fluoro-8-methoxy-1,4-dihydro-4-oxo-3-quinoline carboxylic acid hydrochloride]. Many researchers have reported Moxifloxacin-metal complexes with transition metals and studied their biological applications. We have synthesized novel moxifloxacin- Au(III) and Ag(I) metal complexes ([Au(MOX) 2 (Cl) 2 ].2H 2 O and [Ag (MOX) 2 ].2H 2 O), characterized, and found their biological activities. Moxifloxacin- Au(III) and Ag(I) metal complexes were prepared by adding corresponding aqueous solutions of Au(III) and Ag(I) metal salts to methanolic solution of Moxifloxacin. These metal complexes were characterized by physio-chemical techniques like UV-Vis, 1 H- NMR, FTIR, XRD, DSC, TGA, SEM and microanalytical data. The disc diffusion method was used to study the antibacterial activity of the Moxifloxacin-metal complexes. The structural assessment of these complexes has been carried out based on physio- chemical and spectroscopic methods. The powder X-ray diffraction data of the metal complexes revealed moderate crystallinity. SEM analysis confirms that [Ag(MOX) 2 ].2H 2 O complex has small rods like morphology whereas [Au(MOX) 2 (Cl) 2 ].2H 2 O has well crystalline rods like morphology. The results from DSC of moxifloxacin- Au(III) and Ag(I) metal complexes revealed the interaction between the drug and metals. Further, Au & Ag moxifloxacin metal complexes have shown significant antibacterial activity against gram-positive and gram-negative bacteria. The spectral and analytical results clearly confirmed the coordination chemistry of Au (III) and Ag (I) Moxifloxacin metal complexes. The IR, electronic transition and elemental data led to the conclusion that the geometry of the complex of Au(III) is octahedral and that of Ag (I) complex is tetrahedral. The [Ag(MOX) 2 ].2H 2 O complex has showed good antibacterial activity compared to [Au (MOX) 2 (Cl) 2 ].2H 2 O metal complex. The antibacterial activity studies indicate the metal complexes have more biological activity than free ligand.