【作者】 王楠；

【导师】 周义发；

【作者基本信息】 东北师范大学 ， 生物化学与分子生物学， 2012， 硕士

【摘要】 人参是我国名贵中草药,其主要的活性成分是人参皂苷。目前,已经从人参中分离出的人参单体皂苷有40多种。其中,一些稀有人参皂苷,如Rg3、Rg2、CK、Rh2等,具有重要的生物活性。但这些稀有皂苷在天然人参中的含量较少,甚至根本不存在。它们的制备是目前研究人参的热点之一。本文使用选择性培养基从土壤中分离出20余种人参皂苷转化菌株。其中,从人参种植土壤中分离出一株细菌(编号21),能转化人参皂苷,产生具有较高活性的稀有皂苷。通过16SrDNA测序,确定该细菌为纤维属细菌属细菌(Cellulosimicrobiumsp.Strain 21)。该细菌可转化原人参二醇型皂苷Rb1、Rb2和Rc,转化产物有三种。其中,主要产物为稀有人参皂苷Rg3,另外两种产物分别为人参皂苷C-Y和MC。Cellulosimicrobium sp.Strain 21对人参皂苷Rb1、Rb2 和 Rc 转化路径分别为:Rb1 → Rd → Rg3;Rb2 → Rg3/C-Y;Rc → Rg3/Mc。人参皂苷Rg3具有显著的抗肿瘤活性,使用该细菌转化人参皂苷制备稀有皂苷Rg3具有重要的应用价值。在人参茎叶中,人参皂苷Rd含量较高,并且该菌对Rd的转化效率相对较高,因此本文优化了纤维属细菌转化人参皂苷Rd产生Rg3的条件。得到的优化结果为:最佳底物浓度,1.5 mg/mL;转化最适pH值,7.0-8.0;转化最适温度,31-37℃;转化时间,8h。此外,对该细菌转化原人参三醇型皂苷的能力进行了研究。Cellulosimicrobium sp.Strain 21能转化人参三醇型阜苷 Re 和 Rh1,转化路径如下:Re → Rg2;Rh1→protopanaxatriol。本研究有望为人参皂苷Rg3和Rg2的工业化生产提供可行的方法,并为细菌转化人参皂苷的研究提供理论依据。更多还原

【Abstract】 Ginseng(Panax ginseng C.A.Meyer,Araliacae)is used in Asian countries as a traditional medicine.The main pharmacologically active components in ginseng are ginsenosides.The rare ginsenosides often have better activities than the major ones.At present,More than 40 ginsenosides have been isolated.Their contents in ginseng are different.Some minor ginsenosides(e.g.Rd,Rg3,Rg2,CK,Rh2),whose amount in ginseng is much lower than the major ones,possess unique pharmacological activity.In this paper 20 kinds of microorganisms were screened from soil.A strain isolated from ginseng-cultivating soil was found to be able to transformginsenosides to give a series of bioactive metabolites.The strain was identified to be Cellulosimicrobium sp.strain 21 by 16S rDNA sequencing.Cellulosimicrobium sp.strain 21 transformed protopanaxadiol-type ginsenoside Rbl,Rb2 and Rc to the major product,ginsenoside Rg3,and other two products,ginsenoside compound Y and Mc.The transformation pathways of ginsenoside Rbl,Rb2 and Rc by Cellulosimicrobium sp.strain 21 were found to be:Rb1→ Rd → Rg3;Rb2 →Rg3/compound Y;Rc → Rg3/ginsenoside Mc.Ginsenoside Rg3 was a potential molecule with remarkable anti-tumor activity.Therefore,Cellulosimicrobium sp.strain 21 would be useful in ginsenoside Rg3 production.The biotransformation pathways of protopanaxatriol-type ginsenosides by Cellulosimicrobium sp.strain 21 were studied as follows:Re → Rg2;Rhl → protopanaxatriol.Therefore,the main products of protopanaxatriol-type ginsenosides by Cellulosimicrobium sp.strain 21 were ginsenoside Rg2 and PPT.Rd and Re in Ginsenosides from stems and leaves were higher than the other Ginsenosides.And Cellulosimicrobium sp.strain 21 in transformation of Rd with relatively high efficiency.The optimum conditions were determined:Optimum substrate concentration,1.5 mg/mL;pH,7.0-8.0;temperature,31-37℃.The experimental results provided useful data for the production of ginsenoside Rg2 and Rg3 in industry and for the bacterial transformation of ginsenoside and provide theoretical basis for the research.更多还原