Synthesis and Apoptotic Effects of DNMT Inhibition Targeted Novel Hybrid Molecules Bearing Thiadiazole and Clopidogrel for Cancer Treatment

Despite the efforts to treat cancer with chemotherapeutic agents targeting different mechanisms, cancer is still one of the most important health problems today. The increase in cancer incidence has led researchers to discover new, effective, and selective molecules. For this purpose, novel thiosemicarbazide (<b>3a–3i</b>) and 1,3,4-thiadiazole derivatives (<b>4a–4i</b>) were synthesized from clopidogrel bisulfate and their cytotoxic activities were investigated against glioblastoma (U87) cell line and healthy fibroblast (L929) cell line by MTT assay. Among the synthesized compounds; <b>3b</b>, <b>3g</b>, <b>4b</b>, <b>4d,</b> and <b>4i</b> exhibited higher cytotoxic activities than the standard drug paclitaxel against U87 cancer cells. Cell apoptosis was detected by Bax, Bcl-2, caspase-3 activity, and Annexin V assay. The results displayed that compounds <b>3b</b>, <b>3g</b>, <b>4b</b>, <b>4d,</b> and <b>4i</b> induced apoptosis in U87 cells. Moreover, all compounds were investigated for DNA methyltransferase (DNMT) activity in U87 cells. DNMT enzyme activity was decreased in these compounds’ treated cells. Cyclohexyl ring-bearing compound <b>4d</b>, which showed the highest activity against U87 cells, was the most potent inhibitor of DNMT with an IC₅₀ value of 5.78 ± 1.07 µM compared to paclitaxel (82.05 ± 4.67 µM). Molecular docking studies were also performed to identify the interactions between the compounds and the active sites of DNMT.