凉山彝药火草中新型倍半萜内酯二聚体的发现、结构鉴定及生物活性研究

Gerbera delavayi that is a Liangshan prefectural Yi ethnomedicine for treating cough, asthma, and hemostasis, from which no Sesquiterpene lactone dimer (SLD) has been reported in previous phytochemical studies, which have stimulated our great interest, then we choose this plant to investigate its SLDs and their bioactivities. With the help of the non-specific false-positive alkaloids reaction against SLDs and various chromatographic techniques including silica gel, MCI, C18 reverse silica gel, and sephadex LH-20 column chromatography, the SLDs can be efficiently traced and isolated. Their structures are elucidated by a comprehensive spectroscopic technique, including ECD calculation, and X-ray single crystal diffraction. Lastly, their anti-inflammatory effect and cytotoxicity will be evaluated. The objectives are: (1) the discovery, isolation, and structural elucidation of the novel SLDs from the whole plants of Gerbera delavayi; (2) their anti-inflammatory effect and cytotoxicity; (3) and their structure-activity relationship (SAR), especially their newly formed configuration or conformation after dimerization.

凉山彝药火草为菊科大丁草属钩苞大丁草Gerbera delavayi植物全草，具有止喘咳、止血的作用，但至今还仍未从中发现倍半萜内酯二聚体（Sesquiterpene Lactone Dimers，SLDs）。本研究以SLDs非特异性的生物碱假阳性反应为指导，应用硅胶、MCI、C18反相硅胶、sephadex LH-20等多种色谱材料，定点追踪与分离SLDs，并运用光谱技术、ECD计算及X-射线单晶衍射法鉴定它们的结构。最后，对它们的抗炎、细胞毒活性进行评价。通过研究探讨：（1）火草中新型SLDs的发现、分离、与结构鉴定；（2）它们的抗炎、细胞毒活性；（3）它们的构效关系，尤其是二聚化后新形成的构型/构象的构效关系。

本研究对凉山特色彝药火草（菊科大丁草属钩苞大丁草Gerbera delavayi植物全草）进行了化学成分及其抗兔球虫、止血、抗炎等活性的研究。通过研究，从本彝药共分离鉴定化合物50个，其中新化合物32个，而且它们大多均为起源于乙酸-丙二酸途径的5-甲基-4-羟基香豆素聚酮与单萜的聚合物（5-methyl-4-hydroxycoumarin polyketide-monoterpenes，MPMs）。其中，化合物HC-115是一个内酯环缩合成五元呋喃环的MPM，而化合物HC-95是一个5-甲基-4-羟基香豆素聚酮-苯丙素化合物。通过ECD计算，不仅解决了它们的绝对构型，而且还归纳出判断呋喃线型与呋喃角型5-甲基-4-羟基香豆素聚酮-单萜聚合物的单萜侧链的C-2位绝对构型的CD波谱特征。生物活性评价发现：(1)cyclobrachycoumarin（HC-82）、Brachychromone（HC-83）及HC-85等具有显著的抗炎活性，而且从总体上看，MPMs的抗炎活性强于起源于聚酮途径的5-甲基-4-羟基聚酮香豆素葡萄糖苷 gerberinside（HC-04）的抗炎活性，显示出C-3位萜类片段是抗炎活性的关键结构；（2）香豆素类成分8-甲氧基补骨脂素（HC-01）等具有显著的凝血（止血）作用；（3）钩苞大丁草的乙酸乙酯部位具有有效的抑制兔球虫卵囊孢子化的作用，而且发现与助溶剂二甲亚砜（DMSO）配伍后，抑制（杀灭）兔球虫卵囊孢子化的作用显著提高，以上研究为抗炎、抗兔球虫及止血药物的研发奠定了基础。