Discovery of novel benzoxazole analogues as potential anticancer agent selectively targeting aromatase

Estrogen play an important role in the development of breast cancer in menopausal women. Aromatase, an enzyme that catalyses the last step in the production of estrogen, has been identified as a promising target for clinical development. In the present investigation, novel 2-substituted benzoxazoles were synthesized and evaluated for inhibition against aromatase. Among the studied compound, 6a exhibited 4.04-fold greater cytotoxicity (IC₅₀ = 0.22 µM) than doxorubicin (IC₅₀ = 0.89 µM). It also showed higher selectivity (26.30-304.95) against cancer cells compared to normal (Vero), with a substantial MID of 0.98 µM against the breast cancer subpanel. Furthermore, it displayed a significantly higher affinity for aromatase (IC₅₀ = 64.9 nM) compared to the standard (IC₅₀ = 1850 nM), indicating the mechanism of anticancer action. In the in-vitro enzymatic assay, it demonstrated 8.46-63.14-fold higher selectivity against aromatase compared to other enzymes. Additionally, docking interaction demonstrated a higher dock score of -10.2 kcal/mol to standard (-8.1 kcal/mol). Furthermore, higher stability in the MD simulation established aromatase as an anticancer target and validated the docking methodology. It was also discovered that compound 6a had a binding free energy of -67.72 kcal/mol, which was 1.46 times lower than the standard (-46.17 kcal/mol), supporting the in-silico protocol. Furthermore, MMGBSA discovered that lower binding free energy of Vander Waals force and lipophilicity had a greater impact on aromatase binding affinity and docking scores. These findings imply that compound 6a deserve to be investigated further in the development of potential anticancer agent as aromatase inhibitors.