Investigating the antibacterial, antioxidant, cytotoxic, and computational studies of Co(ii) and Zn(ii) compounds of heteroatom-based dicarboxylic acids

Abstract

This study presents a series of cobalt(II) and zinc(II) based coordination compounds, namely, [Co(toua)(H₂O)]·3H₂O (1), [Co(eoba)(H₂O)₂] (2), [Zn(toua)(H₂O)]·2H₂O (3), and [Zn(eoba)(H₂O)₂] (4), where toua = 3,6,9-trioxaundecanedioate and eoba = 2,2-ethylenebis(oxy)bisacetate. The formation and identification of these coordination compounds were confirmed by elemental analysis, spectroscopic techniques (FTIR and XPS), microscopic analysis, and thermal stability analysis using TGA. Their antibacterial efficacy was tested by the microdilution technique, where compound 1 demonstrated superior activity against three bacterial strains: Escherichia coli (94.8%), Pseudomonas aeruginosa (94%), and Bacillus subtilis (92.3%). Antioxidant capacity was examined by using DPPH method, with compound 1 displaying notable activity at 69.59%, exceeding that of the other complexes. The cytotoxic potential of these complexes against Vero cells was assessed using the MTT assay, revealing that compound 3 has the highest cytotoxicity with an IC₅₀ value of 130.2 µg mL⁻¹. These biological findings prompted further computational investigations, including DFT analysis, molecular docking, and ADME profiling. Docking studies showed that compound 1 had appreciable binding affinities against key bacterial targets: Escherichia coli DNA gyrase B (PDB ID: 6F86) with −6.4 kcal mol⁻¹, Pseudomonas aeruginosa (PDB ID: 3IX3) with −5.8 kcal mol⁻¹, and Bacillus subtilis (PDB ID: 6UF6) with −6.1 kcal mol⁻¹. Additionally, ADME predictions indicated that all four complexes exhibited promising drug-like characteristics and favourable bioavailability profiles.