Relative quantitation of phosphatidylcholines with interfered masses of protonated and sodiated molecules by tandem and Fourier-transform ion cyclotron resonance mass spectrometry.

The present work deals with deconvolution of interfered peaks of protonated and sodiated phosphatidylcholines to solve the problem of relative quantitation of these compounds. The method was developed based on the fact that adducts of phosphatidylcholines with proton and sodium ion give unique characteristic peaks in tandem mass spectrometry. Ultra-high-resolution Fourier-transform ion cyclotron resonance mass spectrometry was used to resolve interfered peaks and thus validate the results of tandem mass spectrometry-based deconvolution. Applicability of the method was tested with synthesized phosphatidylcholines and applied for tissue-spray analysis of the clinical samples and demonstrated good correlation (0.996) between MS/MS and Fourier-transform ion cyclotron resonance mass spectrometry results.

An in vitro and in silico study on the antioxidant and cell culture-based study on the chemoprotective activities of fish muscle protein hydrolysates obtained from European seabass and gilthead seabream.

European seabass (Dicentrarchus labrax, Linnaeus, 1758) (L) and gilthead seabream (Sparus aurata, Linnaeus, 1758) (C) muscles were hydrolysated by Alcalase (Lalc, Calc) and Chymotrypsin (Lch, Cch) then hydrolysates were examined and their peptide profiles obtained. A total of 765, 794, 132 and 232 peptides were identified in Calc, Lalc, Cch and Lch, respectively. Although, Lch and Cch were expected to have more antioxidant capacity because of their peptide profiles, Alcalase hydrolysates observed in vitro, were slightly higher (TEAC assay for Calc: 848.11 ±â€¯60.78 µmol TE/g protein). Maximum inhibition of oxidative stress was determined for Lalc (12.8% ±â€¯4.5%) in MDCK1 cell lines. Highest proliferative capacity observed for Calc (147.0% ±â€¯3.1%) at MTT assay in MDCK1 cell culture. Lch showed the highest chemopreventive effect with a 40-60% decrease for human colon adenocarcinoma cell line HT-29. This research points out the importance of aquatic sources as raw materials for peptide researches.

Peculiarities of data interpretation upon direct tissue analysis by Fourier transform ion cyclotron resonance mass spectrometry.

The importance of high-resolution mass spectrometry for the correct data interpretation of a direct tissue analysis is demonstrated with an example of its clinical application for an endometriosis study. Multivariate analysis of the data discovers lipid species differentially expressed in different tissues under investigation. High-resolution mass spectrometry allows unambiguous separation of peaks with close masses that correspond to proton and sodium adducts of phosphatidylcholines and to phosphatidylcholines differing in double bond number.

Letter: Comparison of pyridine and pyrazine derivatives distributions in exhaled breath and exhaled breath condensate after smoking.

Molecular mass distributions of series of compounds found in exhaled breath after smoking are compared between the direct-breath analysis by extractive electrospray ionization and the analysis of exhaled breath condensate by direct-infusion electrospray ionization mass spectrometry. Although all the analyzed series of compounds are detected by both methods, their relative abundances are different. A number-average mass is used as a quantitative characteristic of the series. It is shown that this value is close for the distributions of the series of compounds in the mass spectrum of exhaled breath condensate and the mass spectrum obtained by summation of direct mass spectra over the breathing time.