Synthesis and antiproliferative evaluation of novel 1,3,4-thiadiazole-S-alkyl derivatives based on quinazolinone

Thirty-five novel 1,3,4-thiadiazole-S-alkyl derivatives based on quinazolinone have been designed and synthesized. The structures of the target compounds 5a − 5p and 6a − 6s were confirmed by their IR, ¹H NMR, ¹³C NMR, HR-ESI-MS spectroscopic data. This study detected their cytotoxicity for mouse fibroblast (normal cells, L929) and their in vitro antiproliferative activities against human cancer cell lines (Hela, MCF-7 and A549) by using CCK-8 assay. The results of all the tested compounds 5a − 5p and 6a − 6s showed that the growth and reproduction of cells were impeded to a certain extent. Compared with the reference drug 5-FU, some compounds even showed better proliferation inhibition against various cancer cells. Among these, most of the compounds had relatively less cytotoxicity to L929 cells. 6-Chloro-2-(2-(benzylthio)-1,3,4-thiadiazol-5-yl)-quinazolin-4(3H)-one (6a) gave expression to the strongest inhibitory activity on Hela cells with IC₅₀ value of 1.40 µM. 6-Chloro-2-[2-(4-trifluoromethylbenzylthio)-1,3,4-thiadiazol-5-yl]-quinazolin-4(3H)-one (6s) displayed high antitumor activities against MCF-7 cells with IC₅₀ values of 3.01 µM. 2-[2-(Benzylthio)-1,3,4-thiadiazol-5-yl]-quinazolin-4(3H)-one (5a) revealed excellent antitumor activities against A549 cells with IC₅₀ values of 2.21 µM.