杀灭鱼类单殖吸虫木脂素类化合物的合成及构效关系研究

Nowadays, the drugs against monogenean parasites are mainly phosphate and mebendazole chemicals. The application of these chemical-based agents has had limited efficacy due to the raised drug-resistance caused by the frequent use of these drugs. Hence, the lack of research and application of parasiticidal bulk drugs has become the bottleneck for the control of monogenean parasites diseases. The study of natural active compounds is one of important approaches to develop new pollution-free aquacultural drugs, control aquaculture diseases, as well as guarantee the security of food and environment. In this project, dibenzylbutyrolactone skeleton of lignin were obtained by total synthesis from 3,4-dihydroxybenzaldehyde, benzyl bromide and dimethyl succinate through oxidation, reduction and condensation reaction. A series of lignans derivatives were then obtained by means of one-step methylation, esterification or glycosylation of dibenzylbutyrolactone skeleton, specifically determining the functional groups with parasiticidal activity and toxicity groups to fish through the research of the structure-activity relationship which can be achieved by the synthesis of lignans derivatives and detection their parasiticidal activity. Quantitative structure-activity relationship models (QSAR) were established to predict the parasiticidal activity of the synthetic compounds for the sake of setting up a fast and feasible method for the design, prediction and screening of lignan parasiticides. This research not only lays the theoretical foundation for the development of lignan drugs against fish parasites, but also provides new ideas for the innovation and creation of base for the pollution-free fishery drugs in the future, which has an important application prospect.

长期以来，杀灭单殖吸虫的渔药主要是有机磷农药、甲苯咪唑等，由于产生的耐药性、水产品安全和生态安全一系列问题，业已成为制约单殖吸虫病害控制的瓶颈。天然产物活性及其构效关系研究是药物研发的理论基础，也是创制无公害渔药、控制水产养殖病害发生、保障食品与水环境安全的重要途径之一。本项目以木质素类化合物为研究对象，采用3,4-二羟基苯甲醛、溴化苄、琥珀酸二甲酯为原料，通过氧化、还原、缩合等方法合成二苄基丁内酯型的木脂素类骨架（母环），再通过甲基化、酯化、糖基化等手段合成一系列木脂素类化合物，结合药效学测定，进行构效关系研究，阐明杀虫活性相关功能基团和对鱼致毒基团；根据合成化合物的杀虫参数建立QSAR模型进行理论验证，建立快速可行的木脂素类杀虫药物分子设计预测和筛选方法。该项目的开展不但为鱼类寄生虫木脂素类药物研究奠定理论基础，同时也为今后无公害渔药基础创新与创制提供新思路和模板，具有重要的应用前景。

天然产物及其衍生合成研究是创制水产新药的理论基础，是提高水产病害控制效果、保障水产品和环境安全的重要途径之一。本研究以具有杀灭单殖吸虫活性以及抗菌活性的天然苯丙素为模板，通过分子设计、结构修饰，合成100多种苯丙素类衍生物。同时采用波谱学方法对合成的化合物进行了结构鉴定，其中37种为新化合物。杀虫活性试验结果表明：大部分衍生物对中型指环虫均表现出不同程度的杀灭活性，其中，有10多种衍生物杀虫活性高于阳性对照药物吡喹酮。烷烃或烯烃取代的木脂素类化合物对中型指环虫的半数有效浓度（EC50）值为1.52-10.14 mg/L，木脂素-杂环类杂合物对中型指环虫的EC50值为2.07-9.78 mg/L。对金鱼的安全性评价结果显示，烷烃或烯烃取代的木脂素类化合物对金鱼的LC50值为9.60-19.76 mg/L，木脂素-杂环类杂合物对金鱼的LC50值为9.26-40.24 mg/L。其中，衍生物4’-[4-(咪唑)丁氧基]牛蒡子苷元（41），4’-[4-(2-甲基咪唑)丁氧基]牛蒡子苷元（42）（具体的名字）的治疗指数TI（LC50/EC50）最高，分别为18.89和19.36。通过生物信息学手段，采用比较分子力场分析法（CoMFA）等计算方法，对化合物的杀虫活性与化合物结构之间的关系进行定量构效关系（QSAR）研究。研究表明引入甲基增大咪唑环的立体结构后，能够显著的增强化合物的杀虫活性。此外，通过扫描电镜、透射电镜和iTRAQ蛋白质组学等技术，初步研究牛蒡子苷元作用单殖吸虫靶点。结果表明：该类药物作用靶标主要位于虫体体被或线粒体上。该研究成果不但为杀灭鱼类寄生虫新渔药研究奠定理论基础，同时也为今后无公害渔药基础创新研究提供了新思路和模板，具有重要科学理论意义和应用前景。