Lipids, particularly phospholipids (PLs) and lysophospholipids (LPLs), are attracting increasing scientific interest for their biological functions in cells and their potential as disease biomarkers for Alzheimer's disease and several types of cancer. Urinary PLs and LPLs could be ideal clinical biomarkers, because urine can be collected easily and noninvasively. However, due to their very low concentrations in urine compared with the relatively large quantity of contaminants in this matrix, efficient extraction and sensitive detection are required for analyzing urinary PLs and LPLs. In this study, various methods for analyzing PLs and LPLs in urine were compared and optimized from a clinical perspective.An optimized lipid extraction method and a matrix for matrix assisted laser desorption/ionization time-offlight mass spectrometry (MALDI-TOF/MS) were established using two external ionization standards and an internal standard mix containing 13 human urinary lipids. 9-Aminoacridine (9-AA) was a useful and effective matrix for the MALDI-TOF/MS analysis of all the internal standard lipids in both positive and negative ion modes. However, it was necessary to determine the proportional lipid concentrations from the balance between the extracted lipid and the matrix. The extraction efficiency and reproducibility of the acidified Bligh and Dyer method were excellent for both positively and negatively charged lipids. Analysis of small volumes of urine was the most efficient with the 9-AA MALDI matrix at concentrations of or below 5 mM. The combined analytical procedures allowed rapid and comprehensive screening of low concentrations of PLs and LPLs in clinical samples.

Lipid metabolism plays an essential role in cell carcinogenesis by affecting the proliferation, migration, differentiation, and motility of cells. 1-3 Among lipid categories, phospholipids (PLs) and lysophospholipids (LPLs) are the most extensively studied. 4 The expression patterns of several PLs and LPLs reportedly differ in prostate cancer (CaP) cells 5 and tissues. 6 Recently, reports have emerged on trained canines being able to detect CaP by sniffing urine samples from these patients. 7 The odor of the urine perceived by the dogs

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In this dataset we provide MALDI-TOF/MS spectra for the testing and application of a quantitative method using external ionization standards (ionization STDs) for peak-intensity normalization. The presented data is related to our recent article entitled “a comparative evaluation of the extraction and analysis procedures for urinary phospholipid and lysophospholipid using MALDI-TOF/MS”. Gradient dilutions of mixture containing thirteen phospho- and lysophospho-lipid species (internal STDs) were mixed with constant concentration of the ionization STDs and analyzed together. Peak intensities of the internal and ionization STDs were picked by a homemade workflow based on OpenMS (steps including noise filtration, baseline subtraction and peak-picking). The peak-intensity ratios between the internal and ionization STDs were linearly correlated with their concentration ratios. Using this method, the evaluation of efficiencies of six different lipid extraction methods was performed in urine samples. In summary, a free and easy-to-use method for phospholipid and lysophospholipid quantitative analysis based on MALDI-TOF/MS is provided in this article.