Synthesis, crystal structures, and biological activity of oxovanadium(V) complexes with similar tridentate hydrazone ligands

Two New Oxovanadium(IV) Compounds Containing Amino Acid Schiff Base and 1,10-Bathophenanthroline Ligands: Syntheses, Crystal Structures, and In Vitro Evaluation of the Anticancer Activities

Two new oxovanadium(iv) compounds containing 1,10-bathophenanthroline (Bphen) and amino Schiff base derivatives [VO(hnd-napha)(Bphen)] (1) and [VO(o-van-met)(Bphen)] (2) were synthesised (where hnd-napha and o-van-met are N-Schiff bases derived from the reaction of 2-hydroxy-1-naphthaldehyde with 3-(1-naphthyl)-l-alanine and o-vanillin with l-methionine, respectively). These compounds were characterised by elemental analysis, infrared spectroscopy, high-resolution mass spectrometry, and single-crystal X-ray diffraction (XRD). Both compounds showed low molar conductance values, indicating that they are non-electrolytes. The XRD results showed that the VIV atoms in both compounds existed in the VO3N3 coordination geometry with Schiff base and Bphen ligands. The in vitro anticancer activities of compounds 1 and 2 were evaluated against A549 human lung carcinoma and HepG2 human hepatoma cell lines using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the results revealed that both compounds were cytotoxic with half maximal inhibitory concentration (IC50) values in the range of 8.22 ± 1.0 to 94.89 ± 3.2 μmol L−1. Notably, compound 2 exhibited much better anticancer activity in vitro against A549 cells (8.22 ± 1 μmol L−1) than [VO(acac)2] (24 ± 6 μmol L−1) or any of our previously reported oxovanadium(iv) compounds, making it comparable in activity to cisplatin (3.1 ± 0.5 μmol L−1). These results therefore suggest that compound 2 could be used as a promising lead for the development of anticancer agents for the treatment of lung cancer.