Oxidative activation of the dietary cancer chemopreventive agent curcumin

描述（由申请人提供）：姜黄素是一种从植物姜黄中分离出来的多酚，具有抗氧化、抗炎和抗肿瘤的生物活性。目前正在多个临床试验中对T进行评估，以预防或治疗炎症和神经退行性疾病，以及肠癌。虽然姜黄素的大量体外靶点已被发现，但其生物活性的精确化学分子机制尚未阐明。我们发现了一种新的，以前未被认识到的姜黄素氧化转化，并且我们在小鼠口服姜黄素后检测到血浆和肠粘膜中大量的氧化代谢物。姜黄素的氧化转化是快速而显著的，并通过反应中间体产生新的代谢物，包括甲醌和环氧丙烷中间体。主要的最终产物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介质的假设。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。具体来说，我们将分析亲电和亲核姜黄素代谢物抑制还原和氧化IKKß的机制，拓扑异构酶II诱导DNA切割的机制，以及醌类中间体形成蛋白质和DNA加合物的机制。在具体目标2中，我们将确定姜黄素氧化转化的产物和中间体，并确定它们的形成机制。在Specific Aim 3中，我们将使用一种新的LC-MS方法，通过同位素标记标准进行定量，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。氧化活化的概念可以为姜黄素的结构和功能的理解提供一个新的范式，对姜黄素作为CAM治疗药物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.