左氧氟沙星与噻二唑类组蛋白去乙酰化酶抑制剂缀合物的合成和抗肿瘤活性

Synthesis and anti-tumor activity of levofloxacin-thiadiazole histone deacetylase inhibitor conjugates

以喹诺酮类药物左氧氟沙星为原料,对其进行结构改造,在左氧氟沙星C-3位羧基上引入噻二唑类组蛋白去乙酰化酶抑制剂(histone deacetylase inhibitor,HDACi)单元,合成了18个新化合物,其结构均经过~1H NMR、~13C NMR和HR-MS进行确证。采用了组蛋白去乙酰化酶(HDACs)试剂盒和CCK8试剂盒测试了目标缀合物的HDACs抑制活性和体外抗肿瘤活性。初步的生物活性测试结果表明,所合成的左氧氟沙星-HDACi缀合物均展现出了较强的HDACs抑制活性,其中肟酸类缀合物对HDACs的抑制活性强于羧酸类和苯甲酰胺类缀合物,尤其是缀合物5d对HDAC1(IC_(50)=0.031±0.011μmol·L^(-1))和HDAC6(IC_(50)=0.019±0.006μmol·L^(-1))的抑制活性最强,强于阳性药物伏立诺他(SAHA);通过分子对接研究发现,缀合物5d除了肟酸基团与HDACs活性口袋底部的氨基酸残基和锌离子相互作用外,其噻二唑基团在HDAC6中还能与氨基酸残基F679形成氢键;在体外抗肿瘤活性中,这些缀合物对SW620、MGC-803、PC-3、NCIH460、MCF-7和Hep G2 6种肿瘤细胞均有较强的抑制作用,其中缀合物5d对肿瘤细胞MGC-803(IC_(50)=0.7±0.05μmol·L^(-1))、NCIH460(IC_(50)=2.3±0.421μmol·L^(-1))、MCF-7(IC_(50)=1.6±0.56μmol·L^(-1))和Hep G2(IC_(50)=3.9±0.26μmol·L^(-1))抑制活性是阳性药物SAHA的3.1倍以上。此外,缀合物对正常的胃黏膜上皮细胞GES^(-1)基本没有毒性,而SAHA却表现出了一定的毒性。

Eighteen novel levofloxacin-thiadiazole HDACi conjugates were designed and synthesized from levofloxacin. The chemical structures of all conjugates were confirmed by ^1HNMR, ^3CNMR and HR-MS spectra. The inhibitory activities of new conjugates were evaluated in an assay with a HDACs reagent kit, and their anti-tumor activities were tested in CCK-8 assay. The results showed that these new conjugates displayed potent inhibitory activity against HDACs, and the hydroxamate conjugates exhibited more potent activity than carboxylic acid and benzamide derivatives. Specifically, conjugate 5d exhibited the most potent anti-HDAC1 （IC50=0.031 ±0.011 μmol·L^- 1） and HDAC6 （IC50=0.019±0.006 μmol·L^- 1） activities, which was more potent than SAHA. Molecular docking studies suggest that the hydroxamate group of conjugate 5d was deeply inserted into the active site to interact with the residues in coordination with the zinc ion. Additionally,the thiadiazole group of conjugate 5d also engaged in hydrogen bonding with F679 in HDAC6, which had been linked to the selectivity of the HDAC isoforms. Moreover, these conjugates displayed significant antiproliferative effects on SW620, MGC-803, PC-3, NCIH460, MCF-7 and HepG2 cells, in particular, conjugate 5d showed the greatest potency against MGC-803 （IC50 = 0.7 ± 0.05 μmol·L^- 1）, NCIH460 （IC50 = 2.3 ± 0.421 μmol·L^- 1）, MCF-7 （IC50= 1.6±0.56 μmol·L^- 1） and HepG2 （IC50=3.9±0.26 μmol·L^- 1）, which was 〉3-fold more potent than SAHA. Additionally, all conjugates were nontoxic to health GES-1 cells, while SAHA showed some toxicity.