Synthesis, cell imaging, biological evaluation and molecular docking studies of novel benzenesulfonyl-substituted curcumin ligand iridium (III) complexes as anti-tumor drugs

In this study, a curcumin derivative was designed, synthesized, and coordinated to form two iridium (III) complexes of the curcumin derivative. The optical properties of the two compounds were studied and the maximum absorption wavelengths of CS-1 and CS-2 were approximately 370 nm, the maximum emission wavelengths were approximately 550–560 nm. HUMO-LUMO energy level analysis revealed that two compounds have good intramolecular charge transfer ability. The cell imaging results indicate that CS-1 and CS-2 have good fluorescence performance and the ability to penetrate biological membranes and enter cells, and compared with curcumin, they have better cell affinity. The results of the cell viability experiments revealed that IC50 of CS-1 on L02, HCT-116, A549, and HeLa cells were 117.6 ± 3.51 µM, 90.14 ± 3.67 µM, 60.82 ± 6.62 µM, and 88.43 ± 5.78 µM, respectively. The IC50 of CS-2 on L02, HCT-116, A549, and HeLa cells were 90.86 ± 4.35 µM, 62.64 ± 7.74 µM, 36.00 ± 4.75 µM, and 79.51 ± 6.43 µM, respectively. CS-1 and CS-2 exhibit significant inhibitory effects on three types of cancer cells and the toxicity of CS-1 and CS-2 to normal cells is less than that to cancer cells. In addition, CS-2 showed greater antitumor activity than CS-1 in HCT-116, HeLa, and A549 cells. The molecular docking results revealed that CS-1 and CS-2 bind to DYRK2 at binding energies of -10.9 kcal/mol and -11.3 kcal/mol, respectively. In summary, we synthesized two iridium (III) complexes of curcumin derivatives with excellent luminescent properties and anticancer activity, which are potential antitumor fluorescent agents.