Oxidative activation of the dietary cancer chemopreventive agent curcumin

描述(申请人提供)：姜黄素是从植物姜黄中分离出来的一种多酚，被公认为具有抗氧化、抗炎和抗肿瘤生物活性。目前正在对T进行多项临床试验，以预防或治疗炎症性和神经退行性疾病，以及肠癌。虽然姜黄素的大量体外靶点已被确定，但其生物学活性的确切化学分子机制(S)尚未阐明。我们发现了一种新的、以前未被发现的姜黄素的氧化转化，我们在小鼠口服姜黄素后，在血浆和肠粘膜中检测到大量的氧化代谢产物。姜黄素的氧化转化是快速、显著的，并通过活性中间体产生新的代谢物，包括苯醌甲醚和螺环氧化物中间体。主要的最终产品是姜黄素的双氧环戊二酮衍生物。我们将检验氧化转化产物是姜黄素药理作用的介体这一假设。在具体目标1中，我们将确定姜黄素氧化转化的生物学后果。具体地说，我们将分析亲电和亲核的姜黄素代谢物抑制还原和氧化的ikkü的机制，拓扑异构酶II诱导DNA裂解的机制，以及中间体苯醌形成蛋白质和DNA加合物的机制。在具体目标2中，我们将鉴定姜黄素氧化转化的产物和中间体，并确定它们的形成机理。在具体目标3中，我们将使用一种新的LC-MS方法，通过同位素标记的标准进行定量，来确定姜黄素及其代谢物的体内代谢、组织分布和药代动力学。氧化激活的概念可能导致一个新的范式来理解姜黄素的结构和功能，对其作为治疗性CAM制剂的临床应用具有重要意义。

DESCRIPTION (provided by applicant): Curcumin, a polyphenol isolated from the plant turmeric, is recognized for its antioxidant, anti-inflammatory and anti-tumorigenic bioactivities. t is currently being evaluated in multiple clinical trials for the prevention or treatment of inflammatory and neurodegenerative diseases, and also for intestinal cancers. Although a large number of in vitro targets of curcumin have been identified, the precise chemical-molecular mechanism(s) of its biological activities have not been elucidated. We have discovered a novel, previously unrecognized oxidative transformation of curcumin, and we have detected abundant levels of the oxidative metabolites in plasma and intestinal mucosa after oral administration of curcumin to mice. The oxidative transformation of curcumin is rapid, prominent, and gives rise to novel metabolites via reactive intermediates, including a quinone methide and a spiro-epoxide intermediate. The major final product is a dioxygenated cyclopentadione derivative of curcumin. We will test the hypothesis that the products of oxidative transformation are mediators of pharmacological effects of curcumin. In Specific Aim 1 we will determine biological consequences of oxidative transformation of curcumin. Specifically, we will analyze the mechanism of inhibition of reduced and oxidized IKKß by electrophilic and nucleophilic curcumin metabolites, the mechanism of induction of DNA cleavage by topoisomerase II, and protein and DNA adduct formation by the quinone methide intermediate. In Specific Aim 2 we will identify the products and intermediates of oxidative transformation of curcumin and determine their mechanism of formation. In Specific Aim 3 we will determine in vivo metabolism, tissue distribution, and pharmacokinetics of curcumin and its metabolites using a novel LC-MS methodology with quantification by isotopically labeled standards. The concept of oxidative activation could result in a new paradigm of understanding the structure and function of curcumin with important implications for its clinical application as a therapeutic CAM agent.