Computational studies, antimicrobial activity, inhibition of biofilm production, and safety profile of the cadmium complex of 1,10-phenanthroline and cyanoguanidine

Abstract

We have previously determined the crystal structure of the metal complex [Cd(1,10-phenanthroline)2(SO4)H2O]cyanoguanidine•5H2O that was characterized by spectroscopic measurements. The antibacterial activity was also determined by the agar diffusion test (zones of inhibition). In the present work, calculations based on density functional theory were performed to determine the contributions of the two different tautomers of cyanoguanidine to the vibrational IR and Raman experimental spectra. Moreover, the antimicrobial (antibacterial and antifungal) activity of the complex and cadmium ion was assessed and the minimum inhibitory concentration (MIC) was determined. The complexation increased the antimicrobial activity against Pseudomonas aeruginosaATCC 27853 and inhibited the biofilm production of this pathogen. Antimicrobial studies were coupled with the evaluation of safety, using the Artemia salinaand Ames test. At the concentrations tested, the cadmium complex behaved as a non-mutagenic and non-toxic compound. Therefore, the interaction of cadmium (II) with N and O-containing ligands may provide a promising strategy for the development of novel and safe drugs with antimicrobial activity.