基于氯法齐明的苯吩嗪类衍生物抗狂犬病毒活性与作用机制及化学基础

Rabies is one of the most deadly infectious diseases, and there is still no effective drugs as so far. Using a high-throughput screening from 776 approved drugs, we found that clofazimine based on phenophenine scaffold exhibited good anti-Rabies virus activity in vitro but had difficulty passing through the blood-brain barrier in vivo. To date, the mechanism of its antiviral activity hasn’t been discovered yet and more studies about its structural modification should be done.. Based on our prior work, studies in this project should be carried out from two aspect. On the one hand, the target of clofazimine will be explored and the chemical biology of its antiviral action will be clarified. On the other hand, aiming to strengthen the anti-rabies activity in vivo, systematic structural modification and optimization will be designed with clofazimine as the leading compound. At least 50 new derivatives are going to be designed and synthesized to elucidate the structure-activity relationship. Through the comprehensive evaluations of preliminary pharmacokinetics, safety and pharmaceutical characters, 1-2 candidates which can pass the blood-brain barrier more easily and have wide therapeutic window and good druggability will be selected. Furthermore, this project will complete the overall framework of chemistry and chemical biology research on their anti-rabies activity. This project will provide some evidence that clofazimine and its derivatives might can become a new candidate against rabies, and might greatly enhance the study of drugs against Rabies viruses.

狂犬病是致死率最高的传染病之一，目前尚无有效治疗药物。前期我们对临床药物库进行抗病毒高通量筛选，首次发现氯法齐明在体外显示高效的抗狂犬病毒活性，治疗指数较高。但存在不易透过血脑屏障等缺欠；其作用机制尚不清楚，结构修饰空间尚待进一步拓展。. 本项目拟在此原创性工作基础上，一方面以氯法齐明为探针，探索其抗狂犬病毒作用靶标，阐明体内外抗病毒作用机制。一方面以氯法齐明为先导物，以抗狂犬病毒为导向，针对其药代分布存在的诸多缺欠，开展较为系统的结构修饰与优化，设计合成不少于50个衍生物。通过体内药效、药代以及安全性等综合性成药评价，优选出活性及成药性高、血脑屏障透过率明显改善的抗狂犬病毒候选物1-2个，为狂犬病毒引起的感染治疗提供良好的候选物。进而完成其抗狂犬病毒活性、作用机制和化学基础的整体框架研究，为使氯法齐明及其衍生物发展成一类狂犬病毒疾病治疗药物提供重要的科学数据。

狂犬病是致死率最高的传染病之一，目前尚无有效治疗药物。前期通过对临床药物库进行抗病毒高通量筛选，首次发现氯法齐明的体外高效抗狂犬病毒活性，治疗指数较高。通过Time-of-addition实验及细胞融合抑制实验，确定氯法齐明作为膜融合抑制剂发挥抗狂犬病病毒作用。建立小鼠狂犬病病毒致死性感染模型，体内动物实验表明氯法齐明可以延长小鼠的发病时间和死亡时间，提高狂犬病病毒感染生存率约10-20%，且在感染后72小时内开始治疗依然有效。为了提高氯法齐明的透血脑屏障能力及改善色素沉着，对氯法齐明进行成盐改造。制备了29种氯法齐明盐，并对盐化合物进行溶出度和溶解度分析，体外抗狂犬病毒分析及体内抗狂犬病毒分析。氯法齐明盐溶出度都得到改善，大部分盐的溶解度有不同程度提高，其中没食子酸盐的溶解度提高了40余倍。大部分氯法齐明盐的体外活性得到提高。选取五种氯法齐明盐进行体内药效学评价，均未观察到皮肤发红现象，其中氯法齐明水杨酸盐和阿司匹林盐治疗组的小鼠存活率提高。为了提高药物极性，降低脂溶性，研究通过对苯吩嗪骨架上A-D的4个结构片段上引入极性基团和做相应结构修饰与优化，合成一系列LogP 值1.0~4.0的、活性提高的全新氯法齐明类似物。综合药物的理化特性，通过体外抗病毒活性筛选，获得代表性化合物F71并开展急性毒性评价及体内抗病毒初步药效学评价。F71表现出较好的安全性, 可能在延后小鼠狂犬病发作时间和死亡时间等方面起到一定的积极作用。本研究完成了氯法齐明抗狂犬病毒活性、作用机制和化学基础的整体框架研究，为使氯法齐明及其衍生物发展成一类狂犬病毒疾病治疗药物提供重要的科学数据。