Novel azomethine Pd (II)- and VO (II)-based metallo-pharmaceuticals as anticancer, antimicrobial, and antioxidant agents: Design, structural inspection, DFT investigation, and DNA interaction

The new NO bidentate imine ligand, namely, (2-[(3-nitro-benzylidene)-amino]-benzoic acid) (NBA) imine ligand (L), and its Pd (II) and VO (II) complexes have been synthesized and characterized by utilizing different physiochemical methods including elemental analyses, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), molar conductance, and magnetic susceptibility measurements. The stability constant of these complexes has also been determined. In studies of these complexes, they were found to have [M(L)] composition where the ligand acts as a bidentate and coordinates with the various metal ions through azomethine and one oxygen atom. Moreover, the suggested geometrical structure of Pd (II) and VO (II) complexes is square planar and a distorted square pyramid, respectively. Density functional theory (DFT) calculations for the different metal complexes were studied and show a good agreement with the experiment data. The minimum inhibitory concentration method has been applied to evaluate the in vitro antimicrobial activity. Furthermore, the interaction of calf thymus DNA with the metal-imine chelates has been assessed, and Pd (II) complex showed the strongest interaction with DNA for a binding constant value of (9.72 x 10(4) kcal mol(-1)). The cytotoxic activity of the new metal chelates has been evaluated against three human cancer cell lines (hepatic carcinoma HepG2 cells, breast carcinoma cells MCF-7, and colon carcinoma cells HCT-116). It has found that NBAPd complex exhibited a significant decrease in the time and dose of the cell viability than did the reference drug vinblastine. The antioxidant activity of the tested compounds was determined and compared with that of vitamin C as a standard drug. It has been found that the metal complexes exhibit higher activity than the free ligand. The finding from this investigation revealed that the new compounds are considered to be prospective antibiotic and anticancer agents.