白首乌内生真菌及其抗肿瘤次生代谢产物的研究

The root of Cynanchum auriculatum, commonly known as “baishouwu”, is a famous traditional Chinese medicine (TCM), and has been widely used for the treatment of geriatric diseases and prolonging life since ancient times. Modern pharmacological investigations have demonstrated that it possesses significant antitumor activity. Based on the previous papers, C21 steroid constituents are considered as the major bioactive constituents of this TCM, most of them possess antitumor activity. For during the long co-evolution of endophytic fungi and their host plants, endophytic fungi have adapted themselves to their special microenvironments by genetic variation. This could have led to the ability of certain endophytic fungi to biosynthesize some “phytochemicals” originally associated with the host plants. Endophytic fungi have proven to be a rich source of novel organic compounds with interesting biological activities and a high level of biodiversity. The biological and chemical studies will be made of the endophytic fungi of C. auriculatum. In this study, we focus on the number of endophytic fungi from tissues (including roots, stems and leaves) of C. auriculatum. Based on the screening of antitumor activity, active strains can be selected and studied for C21 steroid constituents from their secondary metabolites. Active strains will be identified by colonial characteristics, morphological characteristics and ITS sequence analysis. These bioactive C21 steroid constituents from endophytic fungi of C. auriculatum, once isolated and characterized, may also have potential for use in modern medicine. The prospects of finding new drugs that may be effective candidates for treating malignant tumor in humans are great.

传统中药白首乌，被历代医家视为养生防老的珍品。现代研究表明，白首乌具有显著的抗肿瘤功效，内含的C21甾体类化合物是白首乌中公认的抗肿瘤活性成分。植物内生真菌与宿主长期共存，很有可能从其代谢产物中获得与宿主植物相同或相似的活性成分，是重要的活性次生代谢产物来源。本项目以白首乌植物的内生真菌为研究对象，对其进行生物学和化学研究。研究内容包括：从中药白首乌新鲜药材的根、茎和叶3个组织中分离内生真菌，以抗肿瘤预筛模型为指标筛选活性菌株，通过形态学和分子遗传学手段确认活性菌株系统分类学地位，对活性菌株的C21甾体类次生代谢产物进行系统化学分离，并对得到的C21甾体类成分进行抗肿瘤活性评价。本研究为从具有显著疗效的中药白首乌中分离某些内生真菌来代替原植物提供了科学的依据，进而为传统中药资源的应用及开发提供了一种新的思路，也为开发我国自主创新的新型抗肿瘤药物奠定了有益的理论基础。

白首乌为我国传统常用补益性中药，在抗肿瘤、抗衰老、增强免疫及保护肝脏等方面有明确疗效。最常用的白首乌药材来源为耳叶牛皮消，主产于江苏滨海，为地产道地药材。但由于其分布范围狭窄，用药量巨大，且根茎入药，使原本有限的道地资源急剧减少，目前所用药材多为栽培，产量低且限于江苏地区使用。因而，保护和发展现有的白首乌资源，拓展传统中药应用新思路已迫在眉睫。申请人初步研究结果表明，从白首乌植物内生真菌中筛选出抗肿瘤活性显著的菌株，以及从活性菌株的次生代谢产物中得到C21甾体类成分具有切实可行性，植物的内生菌资源可能成为产生具有生物活性次生代谢产物的重要来源。本项目在前期工作基础上，通过对中药白首乌新鲜药材的根、茎和叶3个组织中分离得到的纯内生菌菌株的抗肿瘤活性预筛与评价，筛选出活性显著且稳定的菌株；结合形态学和分子遗传学手段确定活性菌株的系统分类学地位；同时大量发酵活性内生真菌菌株YCTA-2-Z1代谢产物，对发酵液的活性组分进行化学成分的系统分离。白首乌植物内生菌的生物学和化学研究的结果，为从具有显著疗效的中药白首乌中分离某些内生菌来代替原植物提供了科学的依据，进而为传统中药资源的应用及开发提供了一种新的思路。