基于天然产物补骨脂酚的防御素模拟物的设计合成、抗菌活性及作用机制研究

As a new generation of membrane active antibacterial drugs, small molecule based host-defense peptides (HDPs) mimetics have great clinical application prospects for the treatment of drug-resistant bacterial infections. Because they can effectively overcome the emergence of bacterial resistance. In view of the fact that natural bakuchiol has good antibacterial activity and hydrophobic molecular skeleton characteristics, this project intends to use natural bakuchiol as the starting material to design and synthesize a series of bakuchiol derivative as small molecule based HDPs mimetics, by mimicking the molecular structure and membrane active mechanism of HDPs. Pre-experimental results displayed that cationically modified bakuchiol derivative can increase antibacterial activity and reduce cytotoxicity. Based on the antibacterial and hemolytic activity data, the structure-activity relationship models of these antibacterial drugs were established and their chemical structure characteristics were sought. Comprehensive consideration of antimicrobial activity, toxicity and water solubility, 2-3 candidate antibacterial compounds will be selected. We will explore their time-killing study and ability to induce bacterial resistance, and finally clarify their membrane-targeted bactericidal mechanism. Finally, their in vivo antibacterial activity will be initially assessed. This project will lay a theoretical foundation for the development of novel membrane active antibacterial drugs and provide a new solution for bacterial resistance problems.

小分子防御素模拟物能够有效克服细菌耐药性的产生，作为新一代膜活性抗菌药物用于治疗耐药性细菌感染，具有巨大的临床应用前景。鉴于天然补骨脂酚拥有较好的抗菌活性和疏水的分子骨架特点，本项目拟以补骨脂酚为先导化合物，采用仿防御素的两亲性分子结构和膜活性抗菌机制的设计策略，设计合成基于补骨脂酚的小分子防御素模拟物。预实验结果发现，阳离子改性的补骨脂酚衍生物可以提高其抗菌活性，并降低细胞毒性。拟以抗菌和溶血活性数据为基础，建立该类抗菌药物的构效关系模型，并寻求它们的化学结构特征。综合抗菌活性、毒性和水溶性，优选出2-3个候选抗菌化合物，进而研究它们的时间杀菌曲线和诱导细菌产生耐药性能力，并阐明它们膜靶向的杀菌机制。最后，初步评估它们在动物体内的抗菌活性。本项目将为新型膜活性抗菌药物的开发提供新思路，为细菌耐药性问题的解决提供新方案。

开发新型抗菌药物以解决日益严重的病原微生物耐药问题已迫在眉睫。补骨脂酚对革兰氏阳性菌的抗菌活性较好，但对大多数阴性菌的抗菌活性较差，存在水溶性差和成药性差等缺点。为解决补骨脂酚在实际应用中的缺陷，申请人根据仿防御素化学结构和生物功能的设计策略，合成了一系列基于补骨脂酚的小分子防御素模拟物作为抗菌化合物，通过构效关系研究，筛选得到了三个候选抗菌化合物28，B19和B20。其中烷基胺修饰的化合物28对革兰氏阳性菌（包括MRSA）和阴性菌（MICs = 1.56-3.125 μg/mL）都表现出优异的抗菌活性，具备较低的溶血活性，较高的膜选择性，较好的水溶性以及较低的细胞毒性。而氨基酸修饰的化合物B19和B20对革兰氏阳性菌显示出优异的抗菌活性（MICs=0.39-0.78 µg/mL）；对革兰氏阴性菌也表现出良好的抗菌活性（MICs=6.25-12.5 µg/mL）。但与化合物28相比，它们具备更低的细胞毒性，更高的膜选择性和更佳的成药性。在进一步的生物学研究中发现这三个候选抗菌化合物均为膜活性抗菌剂，以浓度依赖性的方式破坏细菌膜的完整性，导致细菌细胞死亡，达到快速杀菌作用，并能够克服细菌耐药性的产生。而且在细菌导致的小鼠角膜感染模型中显示出优异的抗菌效果，其疗效可与市售万古霉素或加替沙星相比拟，具备开发为新型抗菌药物的潜力。该项目的研究成果和设计策略有望为缓解抗菌药物耐药危机提供新思路和化合物基础。在本项目的资助下，申请人于J Med Chem和Acc Chem Res等国际权威期刊发表论文11篇，授权发明专利1件。