Synthesis, characterization and in vitro evaluation of cytotoxicity and antibacterial properties of vanadyl complexes of the pyridoxal Schiff bases

In the current study, we synthesized new vanadyl complexes of the N,N′-dipyridoxyl(1,2-propanediamine) Schiff bases and characterized them by experimental and theoretical methods. Also, the antibacterial (against strains of S. aureus, P.aeruginosa and E. coli) and cytotoxicity activities of three V(IV) complexes including VO-EN, VO-13 and VO-12 of the pyridoxal SBs were evaluated against human prostate tumor cells (PC3 cell line), where the VO-EN, VO-13 and VO-12 species are V(IV) complexes of the N,N′-dipyridoxyl(ethylenediamine), N,N′-dipyridoxyl(1,3-propanediamine) and N,N′-dipyridoxyl(1,2-propanediamine) Schiff bases, respectively. Deprotonated form of the N,N′-dipyridoxyl(1,2-propanediamine) Schiff base acts as a tetradentate N₂O₂ ligand, which coordinates to the V(IV) via two phenolate oxygens and two azomethine nitrogens. In the square-pyramidal geometry of the synthesized complex (VO-12), an oxo ligand occupies the apical position. The analyzed results for the VO-12 complex were in agreement with the experimental tests, confirming the suitability of its optimized geometry. The synthesized VO-12 complex displays significant and reusable catalytic activities in synthesis of the tetrahydrobenzo[b]pyrans, where the V⁴⁺ central ion is the active site of the catalyst. All investigated SB complexes were active against P.aeruginosa, while VO-13, VO-12 and VO-EN complexes revealed no activity against E. coli and S. aureus, respectively. All complexes showed considerable cytotoxic against PC3 cells. Our results suggested that these complexes decreased the cell viability after 48 h and the VO-12 complex showed the highest cytotoxicity. These observations suggested that the VO-EN, VO-13 and VO-12 species can be cytotoxic materials for pharmaceutical applications. In addition, in a dose-dependent manner, these compounds can be consider as potent antimicrobial agents.