Zinc(II) Complexes with Dimethyl 2,2′-Bipyridine-4,5-dicarboxylate: Structure, Antimicrobial Activity and DNA/BSA Binding Study

Two zinc(II) complexes with dimethyl 2,2 '-bipyridine-4,5-dicarboxylate (py-2py) of the general formula [Zn(py-2py)X-2], X = Cl- (1) and Br- (2) were synthesized and characterized by NMR, IR and UV-Vis spectroscopy and single-crystal X-ray diffraction analysis. Complexes 1 and 2 are isostructural and adopt a slightly distorted tetrahedral geometry with values of tetrahedral indices tau(4) and tau'(4) in the range of 0.80-0.85. The complexes were evaluated for their in vitro antimicrobial activity against two bacterial (Pseudomonas aeruginosa and Staphylococcus aureus) and two fungal strains (Candida albicans and Candida parapsilosis), while their cytotoxicity was tested on the normal human lung fibroblast cell line (MRC-5) and the model organism Caenorhabditis elegans. Complex 1 showed moderate activity against both Candida strains. However, this complex was twofold more cytotoxic compared to complex 2. The complexes tested had no effect on the survival rate of C. elegans. Complex 2 showed the ability to inhibit filamentation of C. albicans, while complex 1 was more effective than complex 2 in inhibiting biofilm formation. The interactions of complexes 1 and 2 with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) were studied to evaluate their binding affinity toward these biomolecules.

Automated summary

In this study, two isostructural ferrocene complexes were synthesized and evaluated for their antimicrobial and cytotoxic activities. Complex 1 showed moderate activity against Candida strains and higher cytotoxicity compared to complex 2. Both complexes had no effect on the survival rate of C. elegans. Complex 2 inhibited filamentation of C. albicans, while complex 1 was more effective in inhibiting biofilm formation. Additionally, the binding affinity of the complexes with DNA and protein was studied.