Identification of non-steroidal aromatase inhibitors via in-silico and in-vitro studies

INTRODUCTION:: Breast cancer is the most common cancer affecting women worldwide, including Pakistan. More than half of breast cancer patients have hormone-dependent breast cancer, which is developed due to the over-production of estrogen (the main hormone in breast cancer). METHOD:: The biosynthesis of estrogen is catalyzed by the aromatase enzyme, which thus serves as a target for the treatment of breast cancer. During the current study, biochemical, computational, and STD-NMR methods were employed to identify new aromatase inhibitors. A series of phenyl-3-butene-2-one derivatives 1-9 were synthesized and evaluated for human placental aromatase inhibitory activity. Among them, four compounds 2, 3, 4, and 8 showed a moderate to weak inhibitory activity (IC50 = 22.6 - 47.9 µM), as compared to standard aromatase inhibitory drugs, letrozole (IC50 = 0.0147 ± 1.45 µM), anastrozole (IC50 = 0.0094 ± 0.91 µM), and exemestane (IC50 = 0.2 ± 0.032 µM). Kinetic studies on two moderate inhibitors, 4 and 8, revealed a competitive- and mixed-type of inhibition, respectively. RESULT:: Docking studies on all active compounds indicated their binding adjacent to the heme group and interaction with Met374, a critical residue of aromatase. STD-NMR further highlighted the interactions of these ligands with the aromatase enzyme. CONCLUSION:: STD-NMR-based epitope mapping indicated close proximity of the alkyl chain followed by an aromatic ring with the receptor (aromatase). These compounds were also found to be non-cytotoxic against human fibroblast cells (BJ cells). Thus, the current study has identified new aromatase inhibitors (compounds 4, and 8) for further pre-clinical and clinical research. result: A series of phenyl-3-butene-2-one derivatives 1-9were synthesized and evaluated for human placental aromatase inhibitory activity. Among them, four compounds 2, 3, 4, and 8 showed a moderate to weak inhibitory activity (IC50= 22.6 - 42.7 µM), as compared to standard aromatase inhibitory drugs letrozole (IC50 = 0.0147 ± 1.45 nM), and anastrozole (IC50 = 9.4 ± 0.91 nM). Kinetic studies on two moderate inhibitors,4 and 8, revealed a competitive and mixed type of inhibition, respectively. Docking studies on all active compounds indicated their binding adjacent to the heme group and interaction with Met374, a critical residue of aromatase. STD-NMR further highlighted the interaction of these ligands with aromatase. STD-NMR based epitope mapping indicated close proximity of the alky chain followed by an aromatic ring with the receptor (aromatase). These compounds were also found to be non-cytotoxic against human fibroblast cells (BJ cells). conclusion: Thus, the current study has identified new aromatase inhibitors (compounds 4, and 8), and these could be further considered as anti-cancer agents after in-vivo studies.