Iridium(III) Complexes for Lung Cancer Therapy: Recent Advances and Case Studies in DNA Targeting, Antioxidant Activity and Cytotoxicity

Lung cancer remains a leading cause of cancer-related mortality, and resistance to platinum-based chemotherapy necessitates the development of alternative metal-based therapeutics. In this study, two iridium(III) complexes were synthesized and systematically investigated for their photophysical and biological properties. Spectroscopic characterisation confirmed effective ligand coordination and metal-to-ligand charge transfer behaviour. Both complexes exhibited significant interaction with calf thymus DNA, with intrinsic binding constants of 5.01 × 10⁴M^-1 and 1.08 × 10⁴M^-1, and showed strong affinity towards human serum albumin (K_HSA up to 8.30 × 10⁶M^-1). Antioxidant activity assessed by the DPPH assay revealed moderate radical scavenging ability. Cytotoxicity studies using an MTT assay demonstrated concentration-dependent antiproliferative activity against A549 lung cancer cells, with IC₅₀ values of 57.6 µM and 36.0 µM, while maintaining low toxicity towards normal HEK 293 cells.