Development of Isotope Labeling LC鈥揗S for Human Salivary Metabolomics and Application to Profiling Metabolome Changes Associated with Mild Cognitive Impairment
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- 作者：Jiamin Zheng ; Roger A. Dixon ; Liang Li
- 刊名：Analytical Chemistry
- 出版年：2012
- 出版时间：December 18, 2012
- 年：2012
- 卷：84
- 期：24
- 页码：10802-10811
- 全文大小：418K
- 年卷期：v.84,no.24(December 18, 2012)
- ISSN：1520-6882
文摘
Saliva is a readily available biofluid that may contain metabolites of interest for diagnosis and prognosis of diseases. In this work, a differential 13C/12C isotope dansylation labeling method, combined with liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry (LC鈥揊TICR-MS), is described for quantitative profiling of the human salivary metabolome. New strategies are presented to optimize the sample preparation and LC鈥揗S detection processes. The strategies allow the use of as little of 5 渭L of saliva sample as a starting material to determine the concentration changes of an average of 1058 ion pairs or putative metabolites in comparative saliva samples. The overall workflow consists of several steps including acetone-induced protein precipitation, 12C-dansylation labeling of the metabolites, and LC鈥揢V measurement of the total concentration of the labeled metabolites in individual saliva samples. A pooled sample was prepared from all the individual samples and labeled with 13C-dansylation to serve as a reference. Using this metabolome profiling method, it was found that compatible metabolome results could be obtained after saliva samples were stored in tubes normally used for genetic material collection at room temperature, 鈭?0 掳C freezer, and 鈭?0 掳C freezer over a period of 1 month, suggesting that many saliva samples already collected in genomic studies could become a valuable resource for metabolomics studies, although the effect of much longer term of storage remains to be determined. Finally, the developed method was applied for analyzing the metabolome changes of two different groups: normal healthy older adults and comparable older adults with mild cognitive impairment (MCI). Top-ranked 18 metabolites successfully distinguished the two groups, among which seven metabolites were putatively identified while one metabolite, taurine, was definitively identified.