Antibacterial, antifungal, anti-inflammatory evaluation, molecular docking, and density functional theory exploration of 2-(1H-benzimidazol-2-yl)guanidine mixed-ligand complexes: Synthesis and characterization

The aim of the present framework is to synthesize and characterize new cobalt(II) (C1), nickel(II) (C2), and copper(II) (C3) mixed-ligand complexes incorporating bioactive 8-hydroxyquinoline moiety, with synthesized 2-(1H-benzimidazol-2-yl)guanidine (BG) ligand, for investigating their antibacterial, antifungal, and anti-inflammatory potential. The metal complexes structure had been elucidated by the use of a wide range of methods, including elemental analysis, Fourier transform infrared (FT-IR), mass spectra, UV-vis spectra, magnetic susceptibility, thermogravimetric (TG) analysis, and the molar ratio technique of stoichiometry analysis. The resulted metal complexes were found to have octahedral structures in molar ratio of M:BG:Qu as 1:1:2. Density functional theory (DFT) had been used to determine the optimal molecular structure and quantum chemical properties of each material. After that, we looked into the metal complexes' anti-inflammatory and antibacterial properties by testing them in vitro. The disc diffusion test showed that the metal complexes were far more potent against bacteria/fungi than the original ligands. The egg albumin denaturation technique showed that the metal complexes were more potent anti-inflammatory candidates than the free ligands and comparable with the standard reference. Molecular docking analysis against 5JQ9, 6CLV, and cyclooxygenase-2 (COX-2; 5IKT) confirmed the bioactivity behavior of the metal complexes. C3 has the greatest binding affinity among the metal complexes tested. These findings proposed that the metal complexes could form the basis of future antibiotics and anti-inflammatory candidates. Finally, the in vitro activities were reviewed in relation to the DFT and molecular docking data.