Suspect screening analysis is a targeted metabolomics approach in which identification of compounds relies on specific available information such as their molecular formula and isotopic pattern. This method was applied to the study of grape metabolomics with an UPLC/MS high-resolution Q-TOF mass spectrometer (nominal resolution 40,000) coupled with a Jet Stream ionization source. The present paper describes the detailed qualitative and quantitative study of grape stilbenes, the principal polyphenols associated with the beneficial effects of drinking wine. With this approach, a total of 18 stilbene derivatives was identified in two grape samples (Raboso Piave and Primitivo) on the basis of accurate mass measurements and isotopic patterns, and identification was confirmed by MS/MS analysis. The approach can also potentially be applied to the metabolomics of other plant varieties
A 'suspect screening analysis' method for grape metabolomics by ultra-high performance-liquid chromatography (UHPLC) and high-resolution quadrupole-time of flight (QTOF) mass spectrometry was recently developed. This method was applied to study grape monoterpene glycosides, the main grape aroma precursors. Since standard compounds were not available, they were tentatively identified by overlapping various analytical approaches, in agreement with the indications recommended in mass spectrometry (MS)-based metabolomics. Accurate mass and isotopic pattern, MS/MS fragmentation, correlation between fragments observed and putative structures and between liquid chromatography coupled with mass spectrometry (LC/MS) and gas chromatography/mass spectrometry signals were studied. Seventeen monoterpene glycosides were identified without performing the hydrolytic artifacts commonly used to study these compounds which may affect sample profile. This is the first time that a detailed study of these aroma precursors has been carried out by direct LC/MS analysis.
We have recently shown that alpha fetoprotein (AFP) and squamous cell carcinoma antigen (SCCA), biomarkers associated with hepatocellular carcinoma, may be detected in patient sera as circulating immune complexes with IgM, and that assessment of serum levels of AFP-IgM and SCCA-IgM may be used for the detection of liver cancer. In this study we measured the levels of carcinoembryonic antigen (CEA) as free form (FCEA) and complexed to IgMs (CEA-IgM) in sera of patients affected by colorectal carcinoma (CRC) at different stages as well as in healthy subjects. FCEA levels were above the 5 ng/mL cutoff in 43% of CRC patients (31/72) and CEA-IgM levels were above the 200 AU/mL cutoff in 38% of CRC patients (27/72). Serum levels of CEA-IgM immune complexes (IC) and FCEA did not overlap and 64% of patients (46/72) were positive for at least one marker without compromising the detection specificity (94%). Early detection of CRC was significantly improved by CEA-IgM IC assay. CRC patients at an early stage (stage 1) had elevated CEA-IgM levels in 29% of cases (7/24), while FCEA levels were elevated in only 8% of cases (2/24). These results indicate that CEA-IgM is a complementary serological marker to FCEA which is much more sensitive for early stage CRC, and that the combination of these biomarkers may be useful in the early detection of colorectal cancer.
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