Gold(I) N-Heterocyclic Carbene Complexes with 7-Azaindoles Demonstrates In Vitro Antiproliferative Effects on Ovarian Cancer Cells and Anti-inflammatory Activity

The gold(I) N-heterocyclic carbene (NHC) complexes, containing a combination of 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene (iPr) and the corresponding 7-azaindole derivative (HL1–4), were prepared and characterized. The complexes of the composition of [Au(iPr)(Ln)], where n = 1–4 for 5-fluoro-7-azaindole (1), 5-bromo-7-azaindole (2), 3-chloro-7-azaindole (3), and 3-iodo-7-azaindole (4), were further evaluated for their in vitro anticancer and anti-inflammatory activities. The results showed that complexes (1–4) behave as considerably cytotoxic against human ovarian cancer cell line A2780 (with IC₅₀ ≈ 4–9 μM) and cisplatin-resistant cell line A2780R (with IC₅₀ ≈ 7–12 μM, except for 2 with IC₅₀ > 25 μM), providing significantly higher cytotoxicity than the anticancer drug cisplatin. Moreover, they also revealed a relatively good selectivity over normal cells (MRC-5), with selectivity index values of SI > 2.5. Complex 4 showed the ability to interact with l-cysteine and reduced glutathione at normal extracellular and intracellular levels, respectively. Complex 4 was further studied for its cellular effects in A2780 cells using flow cytometry. The ability of complexes (1–4) to influence the activity of pro-inflammatory transcription factor NF-κB and secretion of TNF-α were evaluated, showing that complex 4 reveals comparable effects as the inflammatory drug auranofin.