Synthesis And Biological Activities Study Of Piperonyl-modified Thiazole Derivatives

2-Aminothiazole, a moiety possessing a variety of biological and pharmacological activities, was selected as the nucleus for structural modification according to association principle. Piperonyl, an active group from many natural products, was introduced to the 5-position of thiazole ring, and reasonable modification of the 2-position amino group was performed to give thiazole amides(E, G, H), aromatic amino-thiazole(J) and thiazole Schiff base(K) start from the intermediate(E)-1-(benzo[d][1,3]dioxol-5-yl)-4,4-dimethylpent-1-en-3-one(A). Compounds E, G, H and J were designed as antitumor agents and compounds K were designed as fungicides.(1) Optimization of the synthetic process of StiripentolThe synthetic process of Stiripentol, an antiepileptic drug, was optimized. The key intermediate piperonal was prepared via Vilsmeier reaction. The reaction condition was optimized by single factor experiment method. Stiripentol was synthesized via Meerwein-Poundorf reduction method in an Al(isopropanol)3/isopropanol system with a high yield of 95%.(2) Synthesis and antitumor activities of N-(5-piperonyl-4-(tert-butyl)thiazol-2-yl) amides(E, G, H)2-Aminothiazole was selected as the nucleus, in which was introduced piperonyl, a natural product active group, on the 5-position. At the same time, a series of reasonable structural modification 2-position amino were conducted by the introduction of active groups such as benzoyl, 2-amino-acetyl and 3-amino-propionyl, resulting three types of N-(5-piperonyl-4-(tert-butyl)thiazol-2-yl) amides(Compounds E, G and H) as anticancer agents. The toxicities of the target compounds against He La, A549 and MCF-7 cell lines were screened by MTT method. Compound E8 showed potent antitumor activity against He La cell lines with an IC50 of 7.7 ± 2.3 μM, better than 5-FU. Compounds G2, G6 and G9 showed potent inhibitory activities against He La cell lines with IC50 values of 11.7 ± 1.1 μM, 7.0 ± 3.2 μM and 6.4 ± 2.2 μM respectively, while compound G2 showed good inhibitory activity against A549 cell lines with an IC50 value of 4.6 ± 2.4 μM, all better than 5-FU. Compound H10 showed about the same inhibitory activity against He La cell lines with an IC50 value of 13.8 ± 1.6 μM. Compound G2 was selected for further analysis of the apoptosis induced by such compounds using AO/EB double staining and flow cytometry. The results indicated that compound G2 could suppresses the growth of He La cells by inducing apoptosis and causing cell-cycle arrest at G1 phase.(3) Synthesis and antitumor activities of N-aryl-5-piperonyl-4-(tert-butyl)thiazol-2-amines(J)The amino on 2-position of thiazole ring was replaced with arylaminos to design and synthesize a series of N-aryl-5-piperonyl-4-(tert-butyl)thiazol-2- amines. The crystal structure of compound J31 was determined by X-ray diffraction. All the synthesized compounds were tested their toxicities against He La, A549 and MCF-7 cell lines in vitro. The results revealed that most of the tested compounds showed potent inhibitory activities against the three cancer cell lines, such as compound J7(IC50: 2.06 ± 0.09 μM for A549 and 3.00 ± 0.25 μM for MCF-7), J27(IC50: 2.07 ± 0.88 μM for He La and 3.52 ± 0.49 μM for A549) and J30(IC50: 4.79 ± 0.86 μM for He La, 5.13 ± 0.62 μM for A549 and 4.71 ± 0.47 μM for MCF-7), significantly better than the 5-FU. Compound J24 was selected as a representative for further studies of the anti-tumor mechanism using AO/EB double staining, Hoechst 33342, and cell cycle and apoptosis analysis by flow cytometry. The result illustrated that compound J24 could inhibit the proliferation of He La cells by inducing apoptosis and causing cell-cycle arrest at G2/M and S phase.(4) Synthesis and fungicidal activities of 5-piperonyl-4-(tert-butyl)-Nbenzylidenethiazol-2-amines(K)A series of 5-piperonyl-4-(tert-butyl)-N-benzylidenethiazol-2- amines were designed and synthesized. All the target compounds were tested for their fungicidal activities in vitro against Botrytis cinerea, Phytophthora infestans, Pyricularia oryzae and Septoria tritici, and then the compounds with good in vitro activities were further tested for the fungicidal activities in vivo against Botrytis cinerea, Erysiphegraminis f. sp. Tritici, Phakopsora pachyrhizi, Phytophthora infestans, Puccinia recondita and Septoria tritici, including both leaf disk and whole plant. The ED50 values of compound K19 against Phytophthora infestans, Pyricularia oryzae and Septoria tritici were 0.601 ± 0.9 mg/L、1.75 ± 0.7 mg/L and 0.975 ± 0.6 mg/L respectively, better than the corresponding positive controls. Compound K19 and K4 also showed good fungicida activity in vivo. The control effect against Phytophthora infestans was 83%(leaf disc) in tomato leaf area after treated with compound K19 at the concentration of 100 mg/L. The control effect against Botrytis cinerea was 90%(whole plant) in green pepper plant dealt with compound K4(600 mg/L).