LAUSR

Thymidylate synthase (TS), one of folate-dependent enzymes, is a key and well-recognized target for anticancer agents. In this study, a series of 6-aryl-5-cyano thiouracil derivatives were designed and synthesized in accordance with essential pharmacophoric features of known TS inhibitors. Nineteen compounds were screened in vitro for their anti-proliferative activities toward HePG-2, MCF-7, HCT-116, and PC-3 cell lines. Compounds $$\mathbf{21}_{\mathbf{c}}$$21c, $$\mathbf{21}_{\mathbf{d}}$$21d, and 24 exhibited high anti-proliferative activity, comparable to that of 5-fluorouracil. Additionally, ten compounds with potent anti-proliferative activities were further evaluated for their ability to inhibit TS enzyme. Six compounds ($$\mathbf{21}_{\mathbf{b}}$$21b, $$\mathbf{21}_{\mathbf{c}}$$21c, $$\mathbf{21}_{\mathbf{d}}$$21d, 22, 23 and 24) demonstrated potent dose-related TS inhibition with $$\hbox {IC}_{50}$$IC50 values ranging from 1.57 to $$3.89\,\upmu \hbox {M}$$3.89μM. The in vitro TS activity results were consistent with those of the cytotoxicity assay where the most potent anti-proliferative compounds of the series showed good TS inhibitory activity comparable to that of 5-fluorouracil. Furthermore, molecular docking studies were carried out to investigate the binding pattern of the designed compounds with the prospective target, TS (PDB-code: 1JU6).