SYNTHESES AND CELLULAR STUDIES OF NEW PHOTOSENSITIZERS FOR MEDICAL APPLICATIONS

描述（由申请人提供）：该建议的重点是设计、合成、开发和优化有前途的四吡咯光动力疗法（PDT）光敏剂，用于诊断和治疗癌症和年龄相关性黄斑变性，用于对抗动脉粥样硬化病变，用于从血液中根除病毒，骨髓清除，以及用于抑制传染性海绵状脑病[牛（BSE），羊（痒病）和人类形式（克雅氏病）]。PDT是一种针对特定细胞的光敏剂的光激活的二元疗法。这导致产生单线态氧和其他细胞毒性物质，导致疾病细胞破坏，同时保留健康组织。fda批准的四吡咯光敏剂只有两种——Photofrin和Visudyne；这两种药物都是对肿瘤组织选择性有限的化合物的混合物。提出了三种四吡咯光敏剂的高效有机合成方法：(1)氯e6、(2)异卟啉、(3)苯并卟啉和卟啉的氨基酸、肽和聚乙二醇（PEG）偶联物。在大多数情况下，目的是制备细胞和特异性细胞器靶向光敏剂，用于病变细胞和斑块的PDT治疗。所合成的四吡咯光敏剂将通过与一个或多个氨基酸、短肽或确定长度的聚乙二醇偶联而定向到特定的细胞器（最好是线粒体）。在任何系列的合成致敏剂中，充分的例子将允许研究细胞摄取，细胞内定位和细胞毒性的机制。还将确定最有希望的致敏剂的细胞死亡模式。这项研究将得出结构/活性关系，这对于设计和开发更好、更有效的PDT光敏剂至关重要，可用于癌症、心血管、输血、骨髓净化和海绵状脑病等医学领域。广泛的初步研究已经完成，并显示拟议研究的所有方面的可行性。新药物还将在内部进行细胞摄取、细胞内定位和暗/光毒性的研究，并与顾问一起研究细胞死亡模式（促进细胞凋亡而不是坏死）；根据生物学工作的反馈对方法进行快速修改是可能的。这将有可能平衡药物的生化和物理化学特性与它们的PDT疗效，并利用机理知识来开发更有效的PDT增敏剂。旨在了解新型四吡咯增敏剂的细胞靶向、摄取和亚细胞定位机制，并开发新的高效药物用于医疗用途。

DESCRIPTION (provided by applicant): This proposal focuses on the design, synthesis, development and optimization of promising tetrapyrrole photodynamic therapy (PDT) photosensitizers for use in diagnosis and treatment of cancer and age-related macular degeneration, for use against atherosclerotic lesions, in virus eradication from blood, bone marrow purging, and for inhibition of transmissible spongiform encephalopathies [bovine (BSE), sheep (scrapie) and human forms (Creutzfeld-Jacob disease)]. PDT is a binary therapy involving light-activation of a photosensitizer that has been targeted to specific cells. This results in the generation of singlet oxygen and other cytotoxic species that cause disease cell destruction while sparing healthy tissues. There are only two FDA-approved tetrapyrrole photosensitizers - Photofrin and Visudyne; both of these drugs are mixtures of compounds with limited selectivity for tumor tissue. It is proposed to develop new efficient organic synthesis methods to three types of tetrapyrrole photosensitizer: amino acid, peptide, and polyethylene glycol (PEG) conjugates of (1) chlorin e6, (2) isoporphyrins, and (3) benzoporphyrins and porphycenes. For the most part, the aim is to prepare cell- and specific organelle-targeted photosensitizers for the PDT treatment of diseased cells and plaque. The tetrapyrrole photosensitizers that are synthesized will be directed to specific organelles (preferably the mitochondria) by conjugation with one or more amino acid, short peptide, or PEG of defined length. Sufficient examples within any series of synthetic sensitizers will permit the investigation of mechanisms of cellular uptake, intracellular localization and cytotoxicity. Modes of cell death for the most promising sensitizers will also be determined. This research will result in structure/activity relationships that are crucial in the design and development of better and more effective PDT photosensitizers for use in cancer, cardiovascular, blood transfusion, bone marrow purging, and spongiform encephalopathy areas of medicine. Extensive preliminary studies have been completed and show viability of all aspects of the proposed research. The new drugs will also be investigated in house for cellular uptake, intracellular localization and dark/light toxicity, and with a consultant for modes of cell death (promoting apoptosis over necrosis); rapid modifications of approach will be possible based on feedback from the biological work. It will be possible to balance biochemical and physicochemical characteristics of drugs with their PDT efficacy, and to use mechanistic knowledge to develop more effective PDT sensitizers. It is intended to understand the mechanisms of cellular targeting, uptake and subcellular localization of new tetrapyrrole sensitizers and to develop new highly effective drugs for medical use. PUBLIC HEALTH RELEVANCE: The proposed program is of major relevance to public health because cancer remains the second most common cause of death in the USA, and macular degeneration, atherosclerosis, viral blood and bone marrow contaminants, and spongiform encephalopathies are major world problems. Photodynamic therapy (PDT) is a treatment modality already approved by the FDA that continues to gain clinical acceptance. The full potential can be realized only when new drugs with higher cellular selectivity and specificity are discovered, their mechanisms of biological action investigated, and their efficacy evaluated relative to existing modalities.