Synthesis, Characterization, and Anticancer Activity of Vanadium (III) Complexes With Pyridyl-Triazole Ligands

Three new V (III) complexes with triazole ligands were obtained and fully characterized using regular analytical techniques, including the unequivocal determination of the structure of complex VL ₃ D by single-crystal x-ray diffraction analysis. The formation of VL ₃ D involves an oxidation process from V (III) to V (IV) that can occur under conditions similar to those of biological assays. The biological activity of these complexes was explored on six human cancer cell lines exhibiting lower IC50 values in five of them when compared to cisplatin, noteworthy the fact that complex VL ₂ probed to be more effective against A549 (IC₅₀ = 1.07 μM). At the same time, VL ₁ showed remarkable activity on HCT-15 (IC₅₀ = 3.14 μM). Interestingly and in contrast to cisplatin, the vanadium complexes showed little effect on the healthy fibroblast cells. Mechanistic studies of cell death revealed that VL ₃ selectively induced late-stage apoptosis without promoting necrosis in A549 cells, whereas VL ₂ did not significantly affect apoptotic or necrotic pathways under the conditions tested. These results were complemented with in silico studies and displacement assays, demonstrating the affinity of the complexes for DNA. The results presented in this work are relevant, as there are few reports of similar V (III) compounds explored as potential anticancer agents.