广西壮药薏苡茎叶抗肿瘤活性及其构效关系和作用机理研究

It is the best pathway to find the aboriginal antitumor drug from the natural products worldwide now. Because the researches on both the antitumor constituents in the stems and leaves of Coix lachryma-jobi L.and the antitumor activities of monomeric compound from the stems and leaves of Coix lachryma-jobi L. are still not enough, we will extract the stems and leaves of Coix lachryma-jobi L., one of Guangxi Zhuang medicines, with methanol, ethanol, acetone, chloroform, and water as the solvents, screen some antitumor activities in vitro and in mice?s vivo of these extracts by the activity-tracking method and tumor cell screening will be used during the whole process,separate and purify the chemical constituents by means of organic solvent extraction, silica gel chromatography, gel filtration, reduced pressure column chromatography, macroporous resin, reverse phase silica gel chromatography, thin layer chromatography (TLC), and high performance liquid chromatography (HPLC). The chemical structures will be identified by means of modern wave spectra, optical spectra, and physical and chemical methods. The obtained compounds will be used for the research of anti-proliferation, apoptosis-promoting action, DNA topoisomerase I activity, and DNA direct cutting action. We will elucidate the structure-activity relationship and the action mechanism between the monomeric constituents from the stems and leaves of Coix lachryma-jobi L. and antitumor activities. We will establish the foundation to study the structural modification and synthesis of antitumor monomeric compounds, find the lead compounds, screen the high-performance antitumor drug, make the quality control and pharmacological action research of the stems and leaves of Coix lachryma-jobi L., and prepare further investigation of the stems and leaves of Coix lachryma-jobi L..

从天然药物中寻找抗肿瘤药物，是目前国际上发现抗肿瘤创新药物的最佳途径。针对薏苡茎叶中抗肿瘤成分的研究还不够深入，缺乏薏苡茎叶单体化合物抗肿瘤活性研究这一问题。本项目拟采用甲醇、乙醇、丙酮、氯仿、水等为溶剂，将广西壮药薏苡茎叶提取的浸膏；以活性跟踪分离的方法，全程采用肿瘤细胞跟踪筛选，用体外和小鼠体内筛选抗肿瘤活性部位。用有机溶剂萃取、硅胶层析、凝胶层析、减压柱层析、大孔树脂层析、反相硅胶层析、TLC及HPLC技术对活性组分进行单体分离纯化；并用现代波谱和光谱技术及理化方法进行单体结构鉴定。将所得单体成分进行肿瘤细胞的抗增殖作用和促凋亡作用、对DNA拓扑异构酶I活性的影响和对DNA的直接切割作用的研究，以阐明薏苡茎叶单体成分抗肿瘤活性及其构效关系与作用机理，为进一步研究抗肿瘤化合物的结构修饰和合成、发现先导化合物，筛选高效抗肿瘤药物，以及薏苡茎叶的质量控制和药理作用研究及其深入开发奠定基础。

从天然药物中寻找抗肿瘤药物，是目前国际上发现抗肿瘤创新药物的最佳途径。针对薏苡茎叶中抗肿瘤成分的研究还不够深入，缺乏薏苡茎叶单体化合物抗肿瘤活性研究这一问题。本项目采用甲醇、乙醇、丙酮、氯仿、水等为溶剂，将广西壮药薏苡茎叶提取得浸膏；用体外和小鼠体内筛选抗肿瘤活性部位，结果水提取物浸膏和乙醇提取物浸膏具有最强的抗肿瘤活性。用有机溶剂萃取、硅胶层析、凝胶层析、减压柱层析、大孔树脂层析、反相硅胶层析、TLC及HPLC技术对活性组分进行单体分离纯化并经结构鉴定，得到(20R)-22E-24-ethylcholesta-4, 22-dien-3-one和Cycloartenol两种抗肿瘤活性单体化合物。两种单体化合物对HepG2、Hela、SGC7901等肿瘤细胞均有较好的抗增殖和促凋亡作用，并呈量效关系；对DNA Topo I也有较好的抑制作用，并呈量效关系；而均没有对DNA产生直接切割作用。阐明了薏苡茎叶单体成分抗肿瘤活性及其构效关系与作用机理。构效关系研究表明，影响抗肿瘤活性的因素可能有：是否具有α,β不饱和酮；双键的数目和位置；羟基的取代数目和位置；化合物空间结构。作用机理研究表明，分子结构中的α,β不饱和酮为该类化合物主要的肿瘤细胞毒活性中心，其作用机制是由于生物体内酶的活性琉基与化合物末端亚甲基的碳相结合发生Miche1加成反应，使其-SH失活；阻滞肿瘤细胞于G2/M期；可能在G2/M期通过干扰Topo I活性和阻断线粒体基因组DNA细胞周期来抑制肿瘤细胞增殖；对DNA Topo I均有明显的抑制作用，其作用机理可能是通过先与Topo I结合，阻止了Topo I与底物DNA的正常结合，从而发挥Topo I抑制作用。为进一步研究抗肿瘤化合物的结构修饰和合成、发现先导化合物，筛选高效抗肿瘤药物，以及薏苡茎叶的质量控制和药理作用研究及其深入开发奠定基础。