Identification of Flavonoid Metabolites

描述(由申请人提供)： 黄酮类化合物是一类广泛的酚类植物化学物质，在人类身上表现出化学预防特性。大量证据表明，黄酮类化合物具有抗肿瘤活性，通过中和自由基来保护DNA损伤，并通过调节参与致癌物激活/失活的肝酶来抑制肿瘤的发展。人们普遍认为，黄酮类化合物在食用后被水解成苷元，然后被生物转化为其他物种。由此产生的苷元和代谢物可能会被不同程度的吸收并发挥不同的生理活性，从而使得药代动力学和生物利用度的绘制成为一个复杂的问题。此外，鉴定类黄酮代谢物的分析方法缺乏在血浆、尿液、组织和细胞中检测低水平的特异性，也缺乏必要的化学标准来验证方法和进行准确的定量。这一建议旨在通过以下途径直接解决这些问题：(I)生物转化产物中黄酮类的酶促合成。我们将使用商业上可用的酶来从母体类黄酮苷元中生产葡萄糖醛酸苷和硫酸盐。(Ii)金属络合策略/串联质谱学：我们将开发创新的金属络合方法，近年来我们在这方面取得了显著的成功，我们将利用串联质谱学对生成的类黄酮代谢物进行结构表征和异构体区分。这项拟议工作最重要的成果有两个：1)首次全面分析类黄酮代谢物，2)开发出鉴定类黄酮代谢物的灵敏分析工具。这项工作将提供大量黄酮类代谢物的档案质谱图和经过验证的质谱学方法，并最终为后续的黄酮类化合物的生物利用度、吸收、分布和药代动力学研究提供巨大的进展。

DESCRIPTION (provided by applicant): Flavonoids are a broad class of phenolic phytochemicals that exhibit chemopreventive properties in humans. Extensive evidence suggests that flavonoids display antitumor activities, in terms of protection against DNA damage by neutralization of free radicals and inhibition of tumor development via modulation of hepatic enzymes involved in activation/deactivation of carcinogens. It is generally accepted that flavonoids are hydrolyzed to aglycones upon consumption, then biotransformed to other species. The resulting aglycones and metabolites may be absorbed to different extents and exert different physiological activities, thus making the mapping of pharmacokinetics and bioavailability a complex problem. Moreover, analytical methods to identify flavonoid metabolites have lacked the specificity to detect low levels in plasma, urine, tissues, and cells, as well as suffering from lack of chemical standards necessary to validate methods and allow accurate quantitation. This proposal is aimed directly at addressing these problems via: (i) enzymatic synthesis of flavonoid biotransformation products. We will use commercially available enzymes to produce glucuronides and sulfates from parent flavonoid aglycones. (ii) metal complexation strategies/tandem mass spectrometry: We will develop innovative metal complexation methods, for which we have had outstanding success in recent years, with tandem mass spectrometry for structural characterization of the resulting flavonoid metabolites and for isomer differentiation. The most important outcomes of the proposed work are twofold: 1) the first comprehensive analysis of flavonoid metabolites, and 2) the development of sensitive analytical tools for identification of flavonoid metabolites. This work will provide archival mass spectra of numerous flavonoid metabolites plus validated mass spectrometric methodology, and ultimately afford tremendous inroads for subsequent bioavailability, uptake, distribution, and pharmacokinetic studies of flavonoids.