Unsymmetrical salen-based oxido VIV: Synthesis, characterization, biomolecular interactions, and anticancer activity

Three stable oxidovanadium(IV) [V^IVOL^1–3] complexes (1–3) were synthesized through the incorporation of unsymmetrical salen ligands (H₂L¹⁻³). All the ligands are synthesized, and their vanadium compounds were thoroughly characterized by CHNS analysis, various spectroscopy methods (IR, UV–Vis, NMR spectroscopy), and HR–ESI–MS. The structures of 1–3 were validated through the single-crystal X-ray analysis. UV–Vis and HR–ESI–MS were used to determine the solution stability of the complexes in the aqueous phase, revealing their stability in aqueous/biological medium. Various spectroscopy techniques were used to study the DNA/BSA binding abilities, and the results indicate that 1–3 shows effective biomolecular interactions. The partition coefficient result indicates that 1–3 are highly hydrophobic and may easily permeate the cells. Finally, the in vitro anticancer properties of 1–3 were determined with two cancerous (HT-29 and A549), and the NIH-3T3 normal cell lines. Among the series, 3 is the most cytotoxic, with IC₅₀ values of 6.2 ± 0.2 and 5.3 ± 0.4 μM against HT-29 and A549 cell lines respectively. Moreover, the apoptotic cell death mechanism of 1–3 was assessed through DAPI, AO/EB, and double staining apoptosis experiments.