Synthesis And Bioactivity Evaluation Of Thiazol [5,4-d] Pyrimidine Derivatives

Malignant tumors pose a serious threat to human health.In addition to developing advanced preventive and diagnostic techniques for tumors,developing new and highly effective antitumor drugs is the most basic treatment for cancer.Purine has an indispensable role in human metabolism.Thiazolopyrimidines are a class of important heterocyclic compounds belonging to purine analogs.Therefore,the study of thiazolopyrimidine compounds for our life has a certain value.With the deepening of research in recent decades,the significant biological activity of thiazolopyrimidine has been discovered.It has been found that the nuclear structure of thiazolopyrimidine has a wide range of biological activities such as antiviral,antifungal and antitumor activities.In addition,There are anti-inflammatory,neuroprotection,anti-angiogenesis and CDC25B phosphatase inhibition.It is precisely because of its biological importance that its concern has never ceased.Here,we used thiazolo[5,4-d]pyrimidine for proper substitution as a template for antitumor compounds,designed and synthesized a series of novel thiazolo[5,4-d]pyrimidine derivatives.A total of 47 derivatives were evaluated for their anti-tumor activity and related mechanisms were studied.The results of the structure-activity analysis showed that when the aromatic amine is modified at the R₃ position,the introduction of the electron-withdrawing group or the long-chain structure at the para position has some improvement on the activity result;the piperazine group is used at the R₃ position for substitution,the introduction of long chain and large hindered groups at the 4-position of piperazine can increase the activity of the compound on MGC-803 cells;changing the 4-position of piperazine to an oxygen atom results in better results than the nitrogen and sulfur atoms.Studies on the structure-activity of R₂ have found that the introduction of electron-withdrawing groups on the aromatic ring can effectively increase the activity of the compound.Substitution of the phenyl ring at the R₁ site is slightly better than that of the propyl group.In the thiol substitution series,the thiazole heterocycle is substituted at the R₃ position,and the 4-position unsubstituted is superior to the4-position electron-donating substituent;the change of the 3-position atom affects the compound against the MGC-803 cells and the MCF-7 cells activity.In the structure-activity study of R₂,benzene rings are superior to other substituted phenyl rings and large hinderance groups like naphthyl group.The benzene ring at the R₁ site was slightly better,but the difference was not significant.Finally,the two most active compounds,7z and 8u,were identified,with IC₅₀ values of 1.03?M for MGC-803 cells and 1.22?M for HGC-27 cells,respectively.After that,we investigated its selectivity between tumor cells and normal cells.As a result,compounds 7z and 8u showed good selectivity with Selectivity indices SI of38 and 24.The initial mechanism of choice for the best anti-tumor activity of compound 7z study found that compound 7z not only efficient inhibition of tumor cell growth,and can effectively inhibit its ability to metastasize.In order to further study the anti-proliferative activity of the synthesized compounds on the cells,we analyzed the effect of the compounds by Hoechst 33258 staining and Annexin-V-FITC/Propidium Iodide double staining and found that the compound 7z will make the morphology of cancer cells Changed,induced apoptosis,and showed a concentration-dependent.Finally,we investigated its mechanism of apoptosis,Western blotting results showed that after treatment with the compound,the anti-apoptotic protein Bcl-2 was down-regulated and the apoptotic protein Bax was up-regulated.Caspase-3 and Caspase-9 expression also significantly increased,suggesting that compounds 7z and 8u may induce apoptosis through a mitochondrial pathway induced cascade between the Bcl-2 family and the Casepase family.