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

描述（由申请人提供）：地中海贫血患者一生必须接受输血，因此存在体内铁过量的问题。通过选择性螯合清除体内多余的铁对于患者的生存是必须的，目前使用去铁胺B的治疗方案有严重的局限性。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。铁螯合剂在癌症治疗中的应用也引起了人们对细胞摄取铁的分子机制的极大兴趣。很明显，铁的消耗会对几个细胞过程产生严重的影响。此外，铁对所有生物的生长都是必不可少的。了解铁载体介导的铁在微生物中的运输和释放机制（铁运输和铁同化）将使人们能够操纵其生长所必需的基本过程。这反过来将允许设计新一代治疗方法来控制诸如结核病（由结核分枝杆菌引起）等重要细菌性疾病的毒性。

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.