ELUCIDATION OF THE PANCRATISTATIN CYTOTOXIC PHARMACOPHORE

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 背景和理由 该项目的最终目标是为癌症治疗提供新的治疗药物。从Pancratium littorale鳞茎中提取的生物碱（+）-panvastatin显示出有希望的抗肿瘤和抗病毒活性，目前正在接受美国国家癌症研究所的临床前评估。 然而，由于可从隔离中获得的材料数量有限，这些研究已被搁置。 生物碱的有限的可用性也困扰着努力阐明其作用机制以及结构  活性研究，这可能是确定更有效和/或毒性更低的类似物的关键。因此，发现一种有效和灵活的化学路线，不仅能够制备天然产物本身，而且还能够制备其类似物的多样化库，这将极大地促进这种先导化合物的进一步开发，因此它一直是科学界长期寻求的目标。 方法 这项工作的重点是一个实际的合成pancrestatin为基础的一系列化合物与可变截短部分的分子。 一旦合成，评价化合物的体外和体内抗癌活性。基于所获得的SAR信息，构建了帕帕司他汀药效团，并用于开发一系列类似物，其具有（a）改善的活性/毒性特征，（B）改善的水溶性，和（c）简化的结构，适合于即将进行的临床试验的大规模生产。 结果 在INBRE项目的前几年中，我们开发了一种高度非对映选择性的芳基铜酸酯与g-烷氧基-a，b-烯酸酯的加成，探索了其范围，发现其潜在的适用性不仅限于该项目，而是在合成有机化学中具有普遍的实用性。 我们从理论的角度进一步研究了这种方法，并开发了一种新的基于还原消除的模型来预测这种过程的立体化学结果。 利用该模型，我们预测g-氨基-a，b-烯酸酯将得到顺式异构体占优势的加成产物。 我们用两种不同的L-丝氨酸衍生的烯酸盐系统地研究了这一过程，发现这一过程确实如预期的那样进行。 该方法是互补的反应的g-烷氧基-a，b-烯酸酯和直接适用于合成的结构简化的类似物的潘司他汀。 这项工作已经出版。INBRE基金还使我们能够通过使用高度集中的化合物库进行筛选来鉴定几种有效的生物活性化合物。 这项涉及大量学生并教育他们药物发现过程的工作也已出版。 进一步研究 将积极利用已开发的方法来合成简化的帕帕司他汀类似物，以及涉及大量学生的药物发现小组的进一步发现。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background and Rationale This project is aimed at the ultimate goal of providing new therapeutic agents for the treatment of cancer. The alkaloid (+)-pancratistatin, extracted from Pancratium littorale bulbs, displays promising antineoplastic and antiviral activity and is currently undergoing preclinical evaluation by the US National Cancer Institute. However, the studies have been put on hold due to the limited quantity of material available from isolation. The alkaloids limited availability has also plagued efforts towards the elucidation of its mechanism of action as well as structure  activity studies, which could be crucial for the identification of more potent and/or less toxic analogues. Therefore, the discovery of an efficient and flexible chemical route enabling preparation of not only the natural product itself, but also a diverse library of its analogues will tremendously facilitate further development of this lead compound, hence it has been a long-sought objective of the scientific community. Methods This work focuses on a practical synthesis of pancratistatin-based series of compounds with variable truncated portions of the molecule. Once synthesized, the compounds are evaluated for in vitro and in vivo anticancer activity. Based on the obtained SAR information the pancratistatin pharmacophore is constructed and used for the development of a series of analogs with (a) improved activity/toxicity profiles, (b) improved water solubility, and (c) simplified structures, amenable to a large-scale production for the forthcoming clinical trials. Results In the previous years of the INBRE project we developed a highly diastereoselective arylcuprate addition to g-alkoxy-a,b-enoates, explored its scope and found that its potential applicability is not limited to this project, but rather has a general utility in synthetic organic chemistry. We have further studied this method from a theoretical perspective and developed a novel reductive elimination-based model to predict the stereochemical outcome of such processes. Using the model we predicted that g-amino-a,b-enoates would give the addition products with high preponderance of the syn isomer. We systematically studied such process with two different L-serine-derived enoates and found that this process indeed proceeds as expected. The methodology is complementary to reactions of g-alkoxy-a,b-enoates and directly applicable to the synthesis of structurally simplified analogs of pancratistatin. This work was published. The INBRE funds also allowed us to identify several potent biologically active compounds through screening efforts using highly focused compound libraries. This work, which involves a great number of students and educates them about the drug discovery process, was published as well. Further Study Utilization of the developed methodologies for the synthesis of simplified pancratistatin analogues as well as further discoveries of the drug discovery group, involving a large number of students, will be actively pursued.