白头翁皂苷抗血吸虫新活性的发现及其构效关系和作用机制研究

Schistosomiasis is a popular parasitic disease in tropical and subtropical regions, which has serious damage to the health of human body. Praziquantel, as the only drug for treatment of human schistosomiasis, only has effect on the early children and adult worms, and no precautionary effect, which shows very low curative rate in the schistosomiasis severe epidemic areas. The total saponins from Pulsatilla chinensis showed significant activities against the whole life cycle of schistosomas through pharmacological activity screening in vivo and in vitro, which probably have higher curative rate for the repeating schistosomiasis infected patients than that of praziquantel, whilst the primary experiment results inferred that the target organs and mechanisms between them were different. This project will choose the total saponins from Pulsatilla chinensis as research object, systemically investigate the chemical constitutes, summarize the antischistosomiasis SAR of the saponins from Pulsatilla chinensis on the basis of pharmacological activity screening, expound the efficacious material basis of the antischistosomiasis effect of Pulsatilla chinensis, which can provide leading compounds or candidate molecules for the research and development of new antischistosomiasis drug. Moreover, explore the insecticidal mechanisms of effective extract or effective compound; elucidate the characteristics of antischistosomiasis compared with those of praziquantel, provide scientific basis for the research and development of new antischistosomiasis drug from Pulsatilla chinensis.

血吸虫病是一种流行于热带和亚热带地区，严重损害人体健康的寄生虫病，作为人体血吸虫病唯一的治疗药物吡喹酮，仅对刚钻入皮肤的早期童虫和成虫有效，无预防作用，在血吸虫病重度流行地区，吡喹酮的治愈率低。经体内外药理活性筛选，发现白头翁总皂苷部位对血吸虫整个生活史都有显著的杀伤作用，可能对血吸虫重度流行地区的多次重复感染病人具有优于吡喹酮的疗效；同时，实验结果提示白头翁总皂苷杀虫作用的靶器官和机制可能也不同于吡喹酮。本课题拟以白头翁抗血吸虫有效部位为研究对象，系统研究其中所含的皂苷类化学成分，结合体内外药理活性测试，进行白头翁中皂苷类成分的抗血吸虫构效关系研究，阐明白头翁抗血吸虫的作用物质基础，为开发新型抗血吸虫病新药提供候选药物分子或先导化合物。在此基础上，探索白头翁抗血吸虫有效部位（成分）的杀虫作用机制，并与吡喹酮进行对比研究，初步阐明其抗血吸虫作用特点，为白头翁抗血吸虫病新药研究提供科学依据。

在发现白头翁总皂苷抗血吸虫活性的基础上，采用植物化学的方法对其进行了系统的化学成分研究，分离并鉴定了36个单体化合物，其中新化合物6个。采用体外成虫培养方法，考察了这些皂苷类化合物的抗血吸虫活性，初步总结了其抗血吸虫构效关系规律，筛选出一种含量较高，毒性较低，活性中等的单体皂苷化合物hederacochiside C和一种含量不高，毒性较强，活性显著的单体皂苷化合物Hederacolchiside A1分别进行了体内外的抗血吸虫药效学、作用特点和作用机制研究。hederacochiside C对日本血吸虫和曼氏血吸虫不同生长阶段均有一定的杀虫效果。尽管减虫率比阳性对照药吡喹酮稍低，但其具有较好的抗炎活性，能明显改善肝脏和小肠的炎症症状，为白头翁清热解毒和杀虫活性成分之一。单体皂苷Hederacolchiside A1(8mg/kg)对日本血吸虫和曼氏血吸虫不同生长阶段均有一定的杀虫效果, 其对童虫阶段的减虫率和减卵率明显优于阳性对照药吡喹酮(400mg/kg)，对成虫阶段的减虫率和减卵率和阳性对照药吡喹酮相当。感染日本血吸虫或曼氏血吸虫7d前给予HSA治疗小鼠肝脏细胞排列规则，形态正常，极少有虫卵沉积，淋巴细胞侵润现象极不明显，形态上与正常肝脏组织极为相似。并且在感染7d前给予HSA治疗小鼠肝脏中转化生长因子-β1 (transforming growth factor-β1, TGF-β1)、金属蛋白酶抑制因子-1 (tissue inhibitor of metalloproteinase 1, TIMP-1)、Ⅰ型胶原 (collagen TypeⅠ)极少量表达（图13-18）。综合上述结果我们发现，在感染日本血吸虫或曼氏血吸虫早期给予HSA治疗，感染7-8周后能显著下调小鼠的免疫反应，减少肝脏肉芽肿的形成，提示了HSA有希望成为预防及辅助治疗血吸虫病药物。