Chelators for Iron(III) for Therapeutic Uses and Probing Cellular Iron Transport

描述（由申请人提供）：患有地中海贫血症的患者必须在其一生中接受输血，因此体内存在过量铁的问题。通过选择性螯合在体内清除过量的铁是患者生存的必要条件，目前使用去铁胺B的治疗方案具有严重的局限性。研究必须继续产生更适合临床使用的新一代铁选择性螯合剂。使用铁螯合剂治疗癌症也引起了人们对细胞吸收铁的分子机制的极大兴趣。很明显，铁缺乏会对几个细胞过程产生严重影响。此外，铁对所有生物的生长至关重要。了解铁载体介导的铁在微生物中的运输和释放（铁运输和铁同化）的机制将允许人们操纵对其生长至关重要的基本过程。这反过来又将允许设计新一代的治疗方法来控制这些重要的细菌性疾病的毒力，如结核病（由结核分枝杆菌引起）。 PI和他的团队已经参与了一段时间的生物医学感兴趣的三价阳离子（特别是铁）的诊断和治疗应用的选择性螯合剂的开发。本项目的目标1是利用我们以前的研究结果，开发一种更有效和直接/收敛的固相合成路线，可以快速生成手性三羟基吡啶酮（HOPO），三异羟肟酸酯和主链上具有HOPO和异羟肟酸配体的混合配体。将通过多种方法评估配体的铁选择性结合，包括与EDTA的竞争性交换反应以及与杜克大学的科学家合作。 当前文献的细读表明，存在于几种铁载体中的混合配体系统的铁络合能力（优点和缺点）尚未被广泛研究。在目标2中，我们计划制备在其骨架中具有多种配体（包括柠檬酸盐、异羟肟酸和HOPO）的螯合系统，并系统地评估结构变化对金属离子结合的影响。我们假设这个项目将使我们得到一些新的线索，选择性铁螯合剂。此外，我们的合成方法允许我们改变螯合剂的亲脂性/疏水性，这是生物活性的关键因素。有用的铁螯合剂与探针，可以提供机械洞察铁在微生物中的运输和释放也将是我们的调查目标。 这项研究的驱动力是产生新一代的治疗方法，可以应用于铁超载疾病，对抗结核病等细菌性疾病，并为癌症治疗提供新的线索。拟议的工作可以对公共卫生产生重大的积极影响。

DESCRIPTION (provided by applicant): Patients suffering from ¿-thalassaemia must receive blood transfusions throughout their life and hence have a problem of excess iron in their bodies. In vivo clearance of the excess iron by selective chelation is a must for patient survival and the current treatment regimes with desferrioxamine B have serious limitations. The search must continue to generate a new generation of iron selective chelators that are better suited for clinical use. The use of iron chelators for the treatment of cancer has also sparked a great interest in the molecular mechanisms of iron uptake by the cells. It is very clear that iron depletion can have serious impact in several cellular processes. Also, iron is essential to the growth of all organisms. An understanding of the mechanism governing siderophore mediated iron transport and release in microorganisms (iron transport and iron assimilation) would allow one to manipulate fundamental processes essential to their growth. This in turn will allow the design of a new generation of therapeutics to control the virulence of such important bacterial diseases such as TB (caused by mycobacterium tuberculosis.) The PI and his group have been involved for some time in the development of selective chelators for trivalent cations of biomedical interest (particularly iron) for diagnostic and therapeutic applications. The Aim 1 of this project is to capitalize on our previous results and develop a more efficient and direct/convergent solid phase synthetic route that could rapidly generate chiral tris-hydroxypyridinones (HOPO), tris- hydroxamates and mixed ligands having both HOPO and hydroxamic acid ligands on the backbone. The ligands will be evaluated for their iron selective binding by a number of methods including competitive exchange reactions with EDTA and in collaboration with scientists at Duke University. A perusal of the current literature reveals that the iron complexation abilities (advantages and disadvantages) of mixed ligand systems present in several siderophores has not been widely studied. In Aim 2, we plan to prepare chelating systems that have a variety of ligands including citrate, hydroxamic acid and HOPO in their backbone and to systematically evaluate the effect of structural variation on metal ion binding. We hypothesize this project will allow us to get some new leads for selective iron chelators. Further, our synthetic approach allows us to vary the lipophilicity/hydrophobicity of the chelator, a key factor in biological activity. Useful iron chelators with probes that can provide mechanistic insight on the transport and release of iron in microorganisms will also be a target of our investigation. The driving force for this study is to generate a new generation of therapeutics that can have applications in iron overload diseases, combating bacterial diseases such as TB and give new leads for the treatment of cancer. The proposed work can have a significant positive impact on public health.