【作者】 胡延维；

【导师】 叶德泳； 段文虎；

【作者基本信息】 复旦大学 ， 药物化学， 2009， 博士

【摘要】 自20世纪80年代中期，过去已被控制的传染性结核病出现再流行，多重耐药性结核（MDR-TB）增长趋势明显。现有的抗结核治疗方案还远远不够理想，耐药性菌株尚在不断出现，发现抗结核药物新靶点、研制开发新型抗结核病药物是一项迫在眉睫的任务。莽草酸途径是细菌所特有的必需芳香族化合物的生物合成途径，其酶系是潜在的高选择性抗菌药物的靶点。本毕业论文专题研究旨在发现新型抗耐药的结核药物。课题以结核杆菌莽草酸脱氢酶（SDH）作为靶酶，运用计算机虚拟筛选技术，发现了对SDH有抑制作用的先导化合物SDI01。利用基团替换、生物电子等排原理、拼合原理等药物化学基本方法，对先导化合物的结构进行了改造，通过改变分子结构中苯环上取代基的电性、空间位阻、亲脂性或亲水性，或用芳杂环取代苯环，以及将分子结构中乙胺链改为高哌嗪环等，设计合成了SDI01衍生物共32个，经体外抗菌活性实验，考察了衍生物的抑菌活性变化，进行了初步构效关系研究。从抑菌活性实验结果表明：绝大部分衍生物均显示出抑菌活性，其中7个衍生物的活性强于先导化合物2～4倍，8个与先导化合物相当；在苯环上引入位阻较小的甲基、甲氧基、溴等基团时，可使活性提高，当引入的取代基空间位阻较大（如叔丁基、异丙氧基等）或苯环并合含氧杂环，衍生物活性下降；芳杂环（呋喃、噻吩等）取代苯环使活性下降：将分子结构中乙胺链改为高哌嗪环活性明显提高；其中光学异构体（S，S）-构型的活性稍好。这些设计合成的SDH抑制剂，具有与现有抗结核杆菌药物结构类型不同的新颖结构和全新的作用靶点，预示与现有临床用药没有交叉耐药性，有较好的进一步研究与开发价值。利福霉素类药物是一类重要的抗结核药物，抗菌活性强，但由于结构的相似性，相互之间存在交叉耐药性，目前此类药物的研发的重点在于提高药效，减小交叉耐药的可能性。本课题还对利福霉素类药物进行了研究，针对利福霉素C3位进行了结构改造，利用拼合原理、生物电子等排原理等，设计了8个利福霉素衍生物。体外抑菌实验表明，8个化合物中5个化合物对结核分枝杆菌H₃₇Ra抑菌活性强于利福平，其中化合物DW-35、DW-36和DW-37活性最强，MIC为3～6ng／mL，是利福平的1／16～1／8，而在对临床分离耐利福平结合分枝杆菌的抑菌实验中，这3个化合物也呈现出强于利福平的抑菌作用。采用MTT法对人巨噬细胞THP—1进行毒性实验，化合物DW-35在浓度为3.125～100μg／mL范围内，没有明显的细胞毒性作用，IC₅₀=543.12μg／mL；化合物DW-37在浓度为3.125～12.5μg／mL范围的各组细胞吸光度值也无明显升高（P＞0.05），没有明显的细胞毒性作用，IC₅₀=51.18μg／mL。以上合成的利福霉素衍生物对利福平敏感菌和耐药菌的抑菌活性优于利福平，具有良好的研究和开发前景。更多还原

【Abstract】 Since the mid-1980s, the controlled infectious disease tuberculosis （TB） has beenundergoing resurging. The existing anti-TB treatment program is also far fromsatisfaction, since the resistance strains are still continually emerging, as well as theappearance of multi-drug resistant （MDR） strains of M. tuberculosis have highlighted.Therefore it’s urgent to discover new targets for antituberculotics and develop novelantituberculotics. The shikimate pathway which leads to the biosynthesis of chorismicacid, is characteristic and essential to plants and microorganisms for the biosynthesisof aromatic compounds. The enzymes of this pathway are hence potential targets forthe development of specific antimicrobial agents. This study aimed at discoveringnovel tuberculostatics with no tolerance.Using virtual screening against small molecule bank, the lead compound SDI01were hited as M. tuberculosis shikimate dehydrogenase （SDH） inhibitor with MICvalue of 6μg/mL. In the principles of group replacement, bioisosterism andcombination, we designed and synthesized 32 derivatives of SDI01, and got somepreliminary structure-activity relationships after determining their anti-TB activities invitro. Compounds with small lipophilic group substituent at the C-4 position ofbenzene ring exhibited better activity. When the benzene ring was replaced byheteroaromatic ring, the compounds showed less antibacterial activity. Activity couldbe improved when ethylenediamine group was replaced by homopiperazine ring.Since these new highly potent SDH inhibitors act at new target and possess uniquechemical structures with existing antituberculotics, they are worthy to be furtherstudied and developed.Rifamycins are important agents in the treatment of infectious TB. By the reasonof the tolerance of existing rifamycins, it is important to develop new drugs withoutcross-resistance with currently used drugs. This study was also focused on exploringthe novel rifamycins by modifying the C3 side chain of the rifamycins. We designedand synthesized eight rifamycin derivatives. The preliminary in vitro results of thebiological evaluation demonstrated high antimycobacterial activity of thesecompounds. Derivatives such as DW-35, DW-36 and DW-37 had MICs 8 to 16 times lower than those of rifampicin against sensitive M. tuberculosis strains, and they alsoshowed higher biological activity against all three classes of mutants resistant torifampicin. MTT assay on human macrophages THP-1 cells, compound DW-35appeared no obvious cytotoxicity with the IC₅₀ value 543.12μg / mL in theconcentration range of 3.125-100μg / mL, and compound DW-37 had no significantcytotoxicity in the range of 3.125-12.5μg / mL with the IC₅₀ value 51.18μg / mL.Therefore, these derivatives have good prospects for further research anddevelopment.更多还原