Design, synthesis and anticancer evaluation of 4-Substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidines as dual topoisomerase I and II inhibitors

In this study, we herein report the design, synthesis, and anticancer assessment of a series of new 4-substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidines. The synthesis involved key intermediates such as the 2-aminoester derivative, which underwent a series of reactions to produce compounds 7a-7t. The optimized S_NAr reactions, utilizing microwave irradiation in DMF, led to high yields and efficient preparation of the desired compounds. The biological evaluation revealed significant cytotoxicity of compounds 7b and 7t against MCF-7 breast cancer cell lines with IC₅₀ values of 8.80 ± 0.08 and 7.45 ± 0.26 µM, respectively, demonstrating superior activity to standard controls like camptothecin and etoposide. Both the compounds exhibited dual topoisomerase I and II inhibition (7t > 7b), enhanced reactive oxygen species (ROS) generation in cancer cells, and halted cell cycle at the G2/M phase. Molecular docking and dynamics simulations further supported the higher binding affinity of compound 7t to topoisomerase enzymes compared to 7b and standard compounds. In silico ADME profiling of 7b and 7t confirmed their drug-likeness, while DFT calculations provided insight into their electronic properties.