Transition metal complexes of benzimidazole-based ligands: Synthesis, characterization, biological, and catecholase activities

Heterocyclic ligands 5a and 5b and their metal complexes (1-10) and (11-20) respectively, were synthesized and characterized by mass spectrometry, FT-IR, ESR, 1 H, 13 C NMR and UV-visible spectroscopy. In vitro antifungal activity of the heterocyclic analogs 5a , 5b and metal complexes (1-20) was evaluated against the fungal strains: Candida albicans, Candida glabrata, and Candida tropicalis., The results showed that Fe(III) 2 and Co(II) complex 13 display considerable antifungal activity with MIC values of 350, 375 and 435 mu g/mL and 450, 455, and 455 mu g/mL against C. albicans, C . glabrata, and C . tropicalis, respectively. Promising 5a , 5b , Fe(III) 2 , and Co (II) complex 13 show groove binding mode with Ct-DNA, which has been confirmed by several techniques, including UV-visible, fluorescence spectroscopy, and cyclic voltammetry. PDB ID: 1BNA was used for the molecular docking investigation of the heterocyclic analogs 5a and 5b . The active Fe(III) complex 2 and Co(II) complex 13 are effectively catalyzed for the oxidation of catechol in acetonitrile to its corresponding quinone with turnover number 5.44 x 104 and 9.78 x 104 h- 1 , respectively with first order that follow Michaelis-Menten enzymatic kinetics. The pharmacokinetics properties of the all compounds showed good oral bioavailability. Antioxidant potential of ligands 5a , 5b , Fe(III) 2 and Co(II) complex 13 was further approximated through DPPH free radical and H2O2 with remarkable antioxidant activity.