Esterase-sensitive hyperpolarized 13C probes for simultaneous imag

项目总结： 代谢异常与许多代谢性疾病有关，如癌症、糖尿病和 心血管疾病。代谢状态改变的重要标志包括燃料的变化 组织中酸度调节的偏好和损失。到目前为止，能源的常规评估 活性组织中的新陈代谢和酸度仍然是一个挑战。灵敏的成像方式可以 因此，提供这些重要生物标志物的准确表征是非常必要的。在这 应用，我们的目标是建立一系列超极化(HP)13C丰富的分子，可以 被内源性酶激活以产生pH和代谢成像探针 纸巾。这些富含Hp 13C的化合物的成功开发将允许组织酸度和 注射单次成像后要同时表征代谢信息 探测器。这些应用的候选分子必须在化学上稳定，可以高度极化 经动态核极化，具有较长的13C T1‘S，对酯酶高度敏感 水解液。一旦被水解，这些分子必须迅速分解，形成一对pH成像 探针，HP 13CO2和HP H13CO3-，以及富含HP 13C的代谢底物，如13C- 丙酮酸。在此，我们合成了一系列含~(13)C-烷基混合酸酐的碳酸酯化合物。 碳酸盐和羧基碳的富集物。这些碳中心有很长的T1 它们适用于HP 13C成像应用。此外，这些有机小分子有望 有效地被DNP极化，并显著提高了13C磁共振成像的灵敏度。最后但不是 至少，这些混合酸酐中的酯官能团预计很容易受到 通过酯酶进行的水解。一旦被注射到循环中，我们预计这些HP 13C混合酸酐 碳酸盐会被酯酶迅速水解，产生单酰基碳酸酯分子。这些 中间体预计会分解，产生HP 13CO2和富含HP 13C的代谢 分别用于组织中pH测量和新陈代谢分析的底物。在这项研究的目标1中， 我们将用13C-乙酸乙酯、13C-丙酮酸、 或13C-丁酸酯为酰基。HP 13C参数，如T1、信号增强和化学 还将对这些化合物的稳定性进行评估。在目标2中，我们将调查HP的生产 13CO2/H13CO3-和HP 13C代谢底物在分离的酯酶溶液中通过酯酶降解， 分离大鼠血浆、血液以及大鼠肝脏和心脏组织匀浆。最后，我们将评估 急性毒性以及这些Hp 13C探针在小鼠和大鼠体内的成像效果(目标3)。 这项研究的成功可能导致一系列惠普13C成像探针的出现，从而允许 代谢相关组织中组织pH和能量代谢的同时成像 疾病。

PROJECT SUMMARY: Abnormal metabolism is associated with a number of metabolic diseases such as cancer, diabetes, and cardiovascular diseases. Important markers for the altered metabolic states include changes in fuel preferences and loss of acidity regulations in tissues. To date, routine assessments of energy metabolism and acidity in viable tissues remain a challenge. Sensitive imaging modalities that can provide accurate characterization of these important biomarkers are therefore highly desirable. In this application, we aim to establish a series of hyperpolarized (HP) 13C-enriched molecules that can be activated by an endogenous enzyme esterase to produce both pH and metabolic imaging probes in tissues. Successful development of these HP 13C-enriched compounds will allow for tissue acidity and metabolic information to be simultaneously characterized following an injection of a single imaging probe. Molecular candidates for these applications must be chemically stable, can be highly polarized by dynamic nuclear polarization (DNP), have long 13C T1’s, and be highly sensitive to esterase hydrolysis. Once hydrolyzed, the molecules must quickly decompose to form a pair of pH imaging probes, HP 13CO2 and HP H13CO3-, as well as a HP 13C-enriched metabolic substrate such as 13C- pyruvate. Here, we propose a series of ethyl alkyl mixed anhydride carbonate compounds with 13C- enrichments at both the carbonate and carboxyl carbons. These carbon centers have long T1 making them suitable for HP 13C imaging applications. Moreover, these small organic molecules are expected to be efficiently polarized by DNP with significantly improved 13C MR imaging sensitivity. Last but not least, the ester functional group in these mixed anhydrides is expected to be highly susceptible to hydrolysis by esterase. Once injected into the circulation, we expect that these HP 13C-mixed anhydride carbonates will be rapidly hydrolyzed by esterase producing monoacyl carbonate molecules. These intermediates are expected to decompose, producing HP 13CO2 and a HP 13C-enriched metabolic substrate for pH measurement and metabolism analysis in tissues, respectively. In Aim 1 of this study, we will synthesize 13C-enriched ethyl acyl mixed anhydride carbonates with 13C-acetate, 13C-pyruvate, or 13C-butyrate as the acyl moiety. HP 13C parameters such as T1, signal enhancement and chemical stability of these compounds will also be evaluated. In Aim 2, we will investigate the production of HP 13CO2/H13CO3- and HP 13C metabolic substrate by esterase hydrolysis in solutions of isolated esterase, isolated rat plasma, blood, and homogenates of rat liver and heart tissues. Finally, we will evaluate the acute toxicity as well as the in vivo imaging efficacy of these HP 13C probes in mice and rats (Aim 3). Successful execution of this study could lead to a series of HP 13C imaging probes that allow for simultaneous imaging of tissue pH and energy metabolism in tissues associated with metabolic diseases.