Design,synthesis And Biological Evaluation Of Uracil Derivatives Bearing 1,2,3-triazole Moiety As Potential Antitumor Drugs

Objective:Thymidylate synthase?TS?,a crucial enzyme for DNA synthesis,is responsible for catalyzing the conversion of deoxyuridine monophosphate?dUMP?by methylation to deoxythymidine monophosphate?dTMP?.In the absence of salvageable extracellular thymidine,this process is the only de novo source of dTMP,which is subsequently metabolised to thymidine triphosphate?dTTP?,exclusively for incorporation into DNA during synthesis and repair.Inhibition of TS activity causes dTMP loss,resulting in intracellular DNA synthesis that does not proceed normally,ultimately leading to cell death.TS is therefore an ideal target for cancer chemotherapy,and it is of great significance to develop novel TS inhibitors with high efficiency and low toxicity.Methods:In this paper,5-fluorouracil and pemetrexed were used as lead compounds.Based on their mechanism of action,using a stratey of pharmacophore combination,a series of novel TS inhibitors were designed and synthesized,which were N-??1-?R-substituted phenyl?-1H-1,2,3-triazol-4-yl?phenyl?-2,4-dioxo-1,2,3,4-tetrahydro pyrimidine-5-sulfonamide derivatives.By retrosynthetic analysis,we choosed a suitable scheme which has many advantages such as available raw materials,moderate cost and high yield to prepare the target compounds.First,2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-sulfonyl chloride?L2?was obtained by chlorosulfonation using uracil as a starting material.Then the preparation of different substitute azide benzene involved diazo-reaction and displacement reaction with sodium azide.The key intermediates?1-?R-substituted phenyl?-1H-1,2,3-triazol-4-yl?aniline?L5a-L7j?were obtained in high yields by the click chemistry reaction between aryl-azides and corresponding ethynyl aniline.Finally,a nucleophilic substitution between the key intermediates?L5a-L7j?and 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-sulfonyl chloride?L2?was done to obtain the target compounds?L8a-L10j?.The structures of all target compounds were characterized by 1H NMR,13C NMR and HRMS spectra.All synthesized compounds were evaluated by in vitro antiproliferation assays against three human cancer cell lines:A549?human lung adenocarcinoma cells?,OVCAR-3?human ovarian cancer cells?,SGC7901?human gastric cancer cells?and one human normal cell lines HPAEpiC?human alveolar epithelial cells?by MTT assay using pemetrexed as a positive control.Meanwhile,western blot analysis was performed to explore the antitumor mechanism.Results and Conclusion:?1?We designed and synthesized 30 uracil derivatives bearing1,2,3-triazole moiety,namely N-??1-?R-substituted phenyl?-1H-1,2,3-triazol-4-yl?phenyl?-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-sulfonamide derivatives.?2?The vast majority of targets compounds showed good to moderate antiproliferative activities against three cancer cell lines,especially on A549 cells.Among them,compound L8j exhibited the most excellent antitumor activity against A549 cells(IC₅₀=1.18?M),with a low toxicity on healthy cells.?3?Western blot analysis showed that compound L8j could induce A549 cells apoptosis by activating caspase-3,and reducing the ratio of bcl-2/bax by down-regulating the expression of bcl-2 proteins while increasing the expression of bax proteins.