Design, Synthesis, and Docking of Novel Tropane Hybrids as Potent Hsp90 Inhibitors with Potential Anti-Breast Cancer Activity.

Background and objective: Breast cancer is the most common form of cancer in women and is the leading cause of cancer-related deaths among women globally. In this study, we aimed to synthesize a series of tropane derivatives to investigate their Hsp90 inhibitory activity as well as their cytotoxic impact on breast cancer cells (MCF- 7 and MDA-MB-231).

Methods: Novel fused-tropane derivatives were created and produced as inhibitors of Hsp90, taking inspiration from XL888, a tropane medication used for treating cancer. The target compounds were screened in vitro to determine their ability to inhibit the activity of Hsp90.

Results: All tropane derivatives displayed a good submicromolar inhibition of Hsp90 with IC50 values ranging from 52.64 to 76.05 nM, relative to XL888 reference medication (IC50 = 27.78 nM). Among all the compounds examined, tropane derivative 5 exhibited the highest level of Hsp90 inhibitory action, with an IC50 value of 52.64 nM. Furthermore, the cytotoxic activity of all compounds was evaluated against two breast cancer cell lines, namely MCF-7 and MDA-MB-231. Tropane derivative 5 exhibited greater potency than doxorubicin against both cell lines. In addition, it demonstrated a safety profile significantly superior to that of doxorubicin when tested on normal human cells (WI-38 cells), thereby confirming its exceptional level of safety. The western blotting analysis demonstrated a 2.4-fold reduction in Hsp90 expression in MCF-7 cells. Furthermore, the molecular docking analysis has provided additional evidence for the capacity of compound 5 to effectively bind with the target Hsp90 enzyme.

Conclusion: We have succeeded in synthesizing novel tropane hybrids exhibiting significant anti-Hsp90 action, similar to XL888 analogues.