Anticancer Activities of Re(I) Tricarbonyl and Its Imidazole-Based Ligands: Insight from a Theoretical Approach

Rhenium complexes have been observed experimentally to exhibit good inhibitory activity against malignant cells. Hence, our motivation is to explore this activity from a theoretical perspective. In the present study, density functional theory (DFT) and in silico molecular docking approaches were utilized to unravel the unique properties of metal-based rhenium tricarbonyl complexes as effective anticancer drugs. All DFT calculations and geometric optimizations were conducted using the well-established hybrid functional B3LYP-GD(BJ)/Gen/6-311++G(d,p)/LanL2DZ computational method. The FT-IR spectroscopic characterization of the complexes: fac-[Re(Pico)(CO)₃(Pz)] (R1), fac-[Re(Pico)(CO)₃(Py)] (R2), fac-[Re(Dfpc)(CO)₃(H₂O)] (R3), fac-[Re(Dfpc)(CO)₃(Pz)] (R4), fac-[Re(Dfpc)(CO)₃(Py)] (R5), fac-[Re(Tfpc)(CO)₃(H₂O)] (R6), fac-[Re(Tfpc)(CO)₃(Py)] (R7), and fac-[Re(Tfpc)(CO)₃(Im)] (R8) was explored. To gain insights into the electronic structural properties, bioactivity, and stability of these complexes, the highest occupied molecular orbital-lowest unoccupied molecular orbital analysis, binding energy, and topological analysis based on quantum theory of atoms-in-molecules were considered. The anticancer activities of the complexes were measured via in silico molecular docking against human BCL-2 protein (IG5M) and proapoptotic (agonist) BAX 1 protein (450O). The results showed that the studied complexes exhibited good binding affinity (-3.25 to -10.16 kcal/mol) and could cause significant disruption of the normal physiological functions of the studied proteins. The results of DFT calculations also showed that the studied complexes exhibited good stability and are suitable candidates for the development of anticancer agents.