Synthesis of Tamoxifen‐Artemisinin and Estrogen‐Artemisinin Hybrids Highly Potent Against Breast and Prostate Cancer

In the search for new and effective treatments of breast and prostate cancer, a series of hybrid compounds based on tamoxifen, estrogens, and artemisinin were successfully synthesized and analyzed for their in vitro activities against human prostate (PC‐3) and breast cancer (MCF‐7) cell lines. Most of the hybrid compounds exhibit a strong anticancer activity against both cancer cell lines – for example, EC(50) (PC‐3) down to 1.07 μM, and EC(50) (MCF‐7) down to 2.08 μM – thus showing higher activities than their parent compounds 4‐hydroxytamoxifen (afimoxifene, 7; EC(50)=75.1 (PC‐3) and 19.3 μM (MCF‐7)), dihydroartemisinin (2; EC(50)=263.6 (PC‐3) and 49.3 μM (MCF‐7)), and artesunic acid (3; EC(50)=195.1 (PC‐3) and 32.0 μM (MCF‐7)). The most potent compounds were the estrogen‐artemisinin hybrids 27 and 28 (EC(50)=1.18 and 1.07 μM, respectively) against prostate cancer, and hybrid 23 (EC(50)=2.08 μM) against breast cancer. These findings demonstrate the high potential of hybridization of artemisinin and estrogens to further improve their anticancer activities and to produce synergistic effects between linked pharmacophores.