Copper Complexes of 8-Aminoquinoline and Uracils as Novel Aromatase Inhibitors

Background: Currently, aromatase inhibitors (AIs) have been developed for the treatment of breast cancers and other estrogen-related conditions. However, searching for more and new classes of AIs is being investigated. 8-Aminoquinoline (8AQ) is an interesting scaffold to be explored. In particular, 8AQ as its mixed ligands (5-nitrouracil, 5Nu and 5-iodouracil, 5Iu) metal complexes are potential compounds to be studied. Objective: Metal complexes of 8AQ-5Nu/5Iu were investigated for aromatase inhibitory activity and cytotoxicity. Methods: Metal complexes (1-6) and free ligands were evaluated for aromatase inhibitory and cytotoxic activities. Aromatase inhibitory activity of the metal complexes was performed according to a guideline of BD Gentest™ kit using CYP19 enzyme and O-benzyl fluorescein (DBF) as a substrate. Cytotoxic effect of the compounds was tested against normal embryonic lung cell line (MRC) using the MTT assay. Results: Significantly, copper complexes 3 (IC50 = 0.7 μM) and 6 (IC50 = 1.7 μM) were shown to be active aromatase inhibitors with selectivity indices of 24.74 and16.40, respectively. Conclusion: Copper complexes of 8AQ-5Nu (3) and of 8AQ-5Iu (6) were highlighted as novel aromatase inhibitors that could be further developed for therapeutic applications.