New Dimethoxyaryl-Sesquiterpene Derivatives with Cytotoxic Activity Against MCF-7 Breast Cancer Cells: From Synthesis to Topoisomerase I/II Inhibition and Cell Death Mechanism Studies

Breast cancer is a prevalent type of cancer worldwide, leading to both high incidence and mortality, and hence, effective and safe drugs are needed. Because of this, the use of natural products and their derivatives has become a popular strategy for developing new chemotherapeutic agents. In this study, 17 new sesquiterpene-aryl derivatives were synthesized using (-)-drimenol as the starting material. The cytotoxicity of these semi-synthetic derivatives was determined in MCF-7 cells, a breast cancer model, and in a non-tumor cell line, MCF-10, to evaluate selectivity. The results show that five of these sesquiterpene derivatives had IC₅₀ values between 9.0 and 25 µM. Of these, compound <b>14c</b> stands out for its higher cytotoxicity in MCF-7 cells but lower cytotoxicity in MCF-10 cells, being more selective than daunorubicin (selective index values of 44 and 28, respectively). In addition, compound <b>14c</b> induced oxidative stress in MCF-7 cells, activated caspases-3/7, and selectively inhibited topoisomerase II (TOP2) versus topoisomerase I (TOP1) in MCF-7 cells. In silico studies allowed us to propose a binding mode for <b>14c</b> to the TOP2 DNA complex to validate the experimental results. Therefore, this study demonstrated the importance of aryl-sesquiterpene structures and their promising profiles in the search for new bioinspired antitumor drugs in natural products.