喜树幼苗中喜树碱和10-羟基喜树碱对热激的响应特点和意义

植物在长期的生态环境适应过程中,产生了包括生物碱在内的大量次生代谢物。本文以我国特有树种——喜树(Camptotheca acuminata Decaisne)为材料,研究其不同器官中喜树碱(camptothecin,CPT)和10-羟基喜树碱(10-hydroxycamptothecin,HCPT)在不同热激温度和时间情况下的含量变化。CPT和HCPT变化呈现出较好的相互消长关系,并且分别在38℃和40℃达到各自的峰值,比以丙二醛和叶绿素为指标的致死温度低了2-4℃：HCPT在热激过程中的变化较CPT活跃;极易受到攻击和伤害的嫩叶中的生物碱含量变化最大。由此推断,CPT和HCPT遵循“幼嫩和生殖器官优先保护”的原则,从而有效地缓解了高温胁迫,并且HCPT和CPT代表了不同的防御策略。     

喜树碱和10-羟基喜树碱受喜树生长发育调控的不同特点

为了揭示喜树碱(camptothecin, CPT)和10-羟基喜树碱(10-hydroxycamptothecin, HCPT)在喜树(Camptotheca acuminata Decaisne)体内代谢的生理调控机制及这两种类似物之间的关系和作用,运用高效液相色谱技术对种子形成、成熟、萌发和幼苗生长过程中喜树碱和10-羟基喜树碱的代谢动态进行了全面的研究.结果表明,喜树碱相对稳定地存在于成熟和幼嫩的组织中;10-羟基喜树碱特异性地积累在乳熟期的种子、种芽的子叶、幼嫩的真叶等幼嫩组织中,随着组织的进一步发育和成熟,其含量快速减少,成熟组织中积累极少,并且这两种生物碱的代谢在时间和数量上都呈现出相互消长的特点,由此推断,这两种生物碱不同程度地受生长发育调控的特点可能与喜树的化学防御策略密切相关,并且,它们之间可以相互转化以充分利用有限的氮素资源.     

喜树碱和10—羟基喜树碱受喜树生长发育调控的不同特点

为了揭示喜树碱（camptothecin,CPT)和10-羟基喜树碱（10-hydroxycamptothecin,HCPT)在喜树（Camptotheca acuminata Decaisne)体内代谢的生理调控机制及这两种类似物之间的关系和作用。运用高效液相色谱技术对种子形成,成熟,萌发和幼苗生长过程中喜树三和10-羟基喜树碱的代谢动态进行了全面的研究。结果表明,喜树碱相对稳定地存在于成熟的幼嫩的组织中;10-羟基喜树碱特异性地积累在乳熟期的种子,种芽的子叶,幼嫩的真叶等幼嫩组织中,随着组织的进一步发育和成熟,其含量快速减少,成熟组织中积累极少,并且这两种生物碱的代谢在时间和数量上都呈现出相互消长的特点,由此推断,这两种生物碱不同程度地受生长发育调控的特点可能与喜树的化学防御策略密切相关。并且,它们之间可以相互转化以充分利用有限的氮素资源。     

喜树碱诱导甜菜夜蛾细胞凋亡线粒体途径的MPTP依赖性

【目的】线粒体通透性转换孔(MPTP)的开放可以导致线粒体膜通透性改变,与细胞凋亡关系密切。本研究旨在探索MPTP在喜树碱诱导的昆虫细胞凋亡中的作用,以进一步揭示喜树碱(CPT)诱导昆虫细胞凋亡的机制。【方法】环孢菌素A(CsA)为MPTP开放抑制剂,通过预加入20μmol/L CsA,应用流式细胞仪测定其对CPT和羟基喜树碱(HCPT)诱导的甜菜夜蛾Spodoptera exigua细胞(IOZCAS-SPEX-Ⅱ)凋亡作用的影响,包括细胞内Ca~(2+)浓度变化,线粒体膜电位变化以及活性氧簇(ROS)变化,从而分析MPTP在CPT和HCPT诱导细胞凋亡的作用。【结果】结果显示,10μmol/LCPT和HCPT处理IOZCAS-SPEX-Ⅱ细胞6 h和12 h时,与0.1%DMSO对照组相比,甜菜夜蛾细胞发生凋亡,胞质Ca~(2+)浓度增大,线粒体膜电位降低或丧失,ROS增加,即CPT和HCPT诱导甜菜夜蛾细胞发生凋亡,为线粒体内途径。但经过20μmol/L CsA预处理2 h后再加入CPT和HCPT处理6 h,与0.1%DMSO组相比,细胞凋亡率、胞质Ca~(2+)浓度、线粒体膜电位及ROS产生均无显著差异(P0.05),即CsA抑制了MPTP的开放,从而抑制了CPT和HCPT诱导的甜菜夜蛾细胞凋亡;而加入CPT和HCPT处理12 h时,CsA对MPTP开放的抑制作用显著降低,与单CPT和HCPT处理组相比,细胞凋亡率、胞质Ca~(2+)浓度、线粒体膜电位及ROS差异不显著,即CPT和HCPT诱导的细胞凋亡如常发生。【结论】本研究证实喜树碱和羟基喜树碱诱导甜菜夜蛾细胞凋亡线粒体途径具有MPTP开放依赖性,且首次明确这种依赖性具有时间性。     

喜树的分泌结构及其与喜树碱积累的关系

为了揭示喜树碱(camptothecin,CPT)在喜树(Camptotheca acuminata Decne.)中的积累部位及积累规律,运用组织化学技术和高效液相色谱技术对喜树茎、叶中喜树碱的积累部位和含量进行了相关性分析.结果发现两类分泌结构与喜树碱积累密切相关:一类是分布于幼茎和幼叶表面的单细胞腺毛;另一类是分布于喜树幼茎和幼叶中的由1～2层细胞包围而成的分泌道.由此推断,喜树中的分泌结构为喜树碱的主要积累部位.     

伤害及诱导子对喜树幼苗中喜树碱含量的影响

通过伤害处理和外施诱导子——水杨酸(SA)、茉莉酸甲酯(MeJa)和乙烯利(Ethrel)以及伤害和诱导子复合处理,研究不同处理对喜树中喜树碱(camptothein,CPT)含量的影响。结果表明:(1)4种单独诱导处理均能在一定程度上增强喜树碱的合成,其中水杨酸处理和机械伤害诱导效果最明显,较对照组的喜树碱含量分别提高了47.7%和27.2%,而机械伤害和诱导子复合处理均产生拮抗作用,喜树碱含量降低;(2)诱导作用受诱导剂浓度的影响,SA、MeJa和Ethrel的适宜质量浓度分别为50~100 mg.L-1、5~10 mg.L-1和5~10 mg.L-1。     

抗癌药物喜树碱生产工艺的研究

前言抗癌药物喜树碱是含在我国南方的一种特产值物——珙桐科喜树(Camptothecaacuminata Decne.)中的一种生物碱,其结构为:在喜树的木、根皮和种子中都含有,以种子中台量为最高,主要成伪一为喜树碱 (c amPtothecine),其他还有10一径基喜树碱     

生物技术在喜树碱研究中的应用

喜树碱是从我国特有植物喜树中分离到的一种具有抗癌活性的萜类吲哚生物碱,具有重要的利用和研究价值.本文通过对喜树碱资源的现状及生物技术在喜树碱研究中的应用进行综述.指出喜树碱及其衍生物在植物体内含量甚微,远远不能满足市场的需要,阐明应用生物技术提高喜树碱含量是目前极其有效的研究手段和方法,同时对利用生物技术大量生产喜树碱的研究方向进行了展望.     

喜树的分泌结构及其与喜树碱积累的关系(英文)

为了揭示喜树碱(camptothecin,CPT)在喜树(Camptotheca acuminata Decne.)中的积累部位及积累规律,运用组织化学技术和高效液相色谱技术对喜树茎、叶中喜树碱的积累部位和含量进行了相关性分析。结果发现两类分泌结构与喜树碱积累密切相关:一类是分布于幼茎和幼叶表面的单细胞腺毛;另一类是分布于喜树幼茎和幼叶中的由1～2层细胞包围而成的分泌道。由此推断,喜树中的分泌结构为喜树碱的主要积累部位。     

喜树生物碱在喜树植株中的分布

采用高效液相法测定喜树植株不同部位的生物碱(喜树碱、l0-羟基喜树碱)含量的结果表明,十年生喜树叶中的喜树碱含量最高(0.1102%),非木质化茎的(0.0588%)略高于木质化茎的(0.0491%),主干上部(0.0604%)和主干近根部(0.0641%)高于主干中部(0.0447%),根部一级侧根(0.0968%)中含量也较高.10-羟基喜树碱在二级侧根中含量最高(0.4950%),木质化茎(0.0473%)明显高于非木质化茎(0.0125%),主干中含量分布与喜树碱相似,叶中含量为0.0905%.     

滤光膜对喜树幼苗叶片生长和喜树碱含量的影响

喜树 (Camptotheca acuminata)为中国特有树种 ,因其次生代谢产物喜树碱具有抗癌作用而闻名。通过用黄色、红色、蓝色 3种滤光膜对温室栽培的喜树幼苗进行遮光处理 ,研究了不同光照环境下喜树幼苗叶片生物量、叶绿素含量、光合作用和喜树碱含量的差异。结果表明在 30 d的遮光过程中 ,红膜和蓝膜遮光明显导致幼苗叶片生物量降低 ,黄膜遮光下幼苗叶片生物量在处理后 2 5 d才表现明显降低。不同滤光膜下幼苗叶片叶绿素含量先降低然后升高 ,遮光幼苗的叶绿素 a/ b明显低于日光幼苗。幼苗日最大净光合速率的顺序是 :日光 >黄膜 >红膜 >蓝膜。处理后第 2 0天 ,不同滤光膜下幼苗的光饱和光合速率 (Amax)、光饱和点 (Is)、光补偿点 (Ic)、最大表观量子效率 (AQYmax)都不同程度的低于日光幼苗。处理后第 10天至第 30天 ,遮光幼苗叶片喜树碱含量均显著高于日光下幼苗 ,以蓝膜下幼苗的喜树碱含量最高。蓝膜和黄膜下幼苗的喜树碱产量在后期处理中显著高于日光下幼苗 ,蓝膜下幼苗喜树碱产量在第 30天最高 ,是日光下幼苗的 2 .4 9倍。红膜下幼苗的喜树碱产量在第 10天后与日光下幼苗差异不显著。通过滤光膜遮光促进喜树碱在幼苗叶片中的积累 ,提高了叶片喜树碱产量 ,对喜树碱的生产实践有一定的意义     

不同产地和生长季节喜树叶中喜树碱含量测定

喜树(Camptotheca acuminata)是我国特有抗癌植物。本文通过测定不同产地的喜树幼嫩叶和成熟叶中喜树碱含量表明,均以四川都江堰所产喜树叶中喜树碱含量最高。不同生长月份的喜树嫩叶中喜树碱含量成一条单峰曲线,以7月喜树嫩叶中喜树碱的含量最高。     

不同产地和生长季节喜树叶中喜树碱含量测定

喜树（Camptotheca acuminata）是我国特有抗癌植物。本文通过测定不同产地的喜树幼嫩叶和成熟叶中喜树碱含量表明,均以四川都江堰所产喜树叶中喜树碱含量最高。不同生长月份的喜树嫩叶中喜树碱含量成一条单峰曲线,以7月喜树嫩叶中喜树碱的含量最高。     

Extraction and composition of three naturally occurring anti-cancer alkaloids in Camptotheca acuminata seed and leaf extracts

Naturally occurring camptothecins (CPT) are important sources of chemotherapeutic agents for clinical treatment of cancer. Extraction of CPT from Camptotheca acuminata trees remains to be a cost-effective way in the supply equation compared with a total synthesis. This study conducted a series of experiments to determine efficient solvent for the maximal extraction of CPT and its two derivatives, hydroxycamptothecin (HCPT) and methoxycamptothecin, from seeds and leaves of C. acuminata. Methanol as an extraction solvent demonstrated in seeds a significantly higher recovery of these three alkaloids than dichloromethane and acetone. Methanol concentrations at 70% in water resulted in maximum extraction of all the three alkaloids regardless of the type of plant materials. However, other strengths of methanol, lower or higher, either decreased the extracting power or showed no improvement in the extraction. Seed extract contained all the three alkaloids whereas leaf extract was absent of HCPT. A stable ratio of the three alkaloids was discovered but it was dependent upon seed or leaf extract of C. acuminata, which with various compositions can be produced. Ecological and medicinal implications of the leaf and seed extract characterized with different chemical compositions are discussed.     

Camptothecin, over four decades of surprising findings

Camptothecin (CPT) is a modified monoterpene indole alkaloid produced by Camptotheca acuminata (Nyssaceae), Nothapodytes foetida, Pyrenacantha klaineana, Merrilliodendron megacarpum (Icacinaceae), Ophiorrhiza pumila (Rubiaceae), Ervatamia heyneana (Apocynaceae) and Mostuea brunonis (Gelsemiaceae), species belonging to unrelated orders of angiosperms. From the distribution of CPT and other secondary metabolites, it has been postulated that the genes encoding enzymes involved in their biosynthesis evolved early during evolution. These genes were presumably not lost during evolution but might have been "switched off" during a certain period of time and "switched on" again at some later point. The CPT derivatives, irinotecan and topotecan, are used throughout the world for the treatment of various cancers, and over a dozen more CPT analogues are currently at various stages of clinical development. The worldwide market size of irinotecan/topotecan in 2002 was estimated at about $750 million and at $1 billion by 2003. In spite of the rapid growth of the market, CPT is still harvested by extraction from bark and seeds of C. acuminata and N. foetida. All parts of C. acuminata contain some CPT, although the highest level is found in young leaves (approximately 4-5 mg g(-1) dry weight), approximately 50% higher than in seeds and 250% higher than in bark. The development of hairy root cultures of O. pumila and C. acuminata, and the cloning and characterization of genes encoding key enzymes of the pathway leading to CPT formation in plants has opened new possibilities to propose alternative and more sustainable production systems for this important alkaloid.     

Secretory Structures and Their Relationship to Accumulation of Camptothecin in Camptotheca acuminata （Nyssaceae）

Camptotheca acuminata Decne. (Nyssaceae) is a major source of the anticancer camptothecin (CPT). It is important to understand how CPT accumulates in C.acuminata in order to improve CPT production strategies. The aim of this study was to anatomically and morphologically characterize the secretory structure in leaves and stems of C.acuminata and determine their relationship to accumulation of OPT. Secretory canals and glandular trichomes were found in young stems and young leaves. Secretory canals consisted of a sub-epidermal canal delimited by one to two layers of cells. Glandular trichomes were unicellular. Fluorescence microscopy and OPT analysis showed that OPT was primarily accumulated in secretory canals and glandular trichomes of leaves and stems.