Bioanalysis young investigator: Alexander Medina-Remón.
ABSTRACT Supervisor's supporting comments Alex Medina joined my research group, Natural Antioxidants, in January 2006 to start his PhD program. He has been working intensively and efficiently on several projects; initially for his thesis he developed a new bioanalytical methodology to quantify phenols in urine (Medina-Remón A et al. 2009) to correlate with the hypertension prevention in the PREDIMED study ( www.predimed.org ). Thanks to this new bioanalytical method, we are currently starting collaboration projects with different research centers. In addition, he has been working on other research projects on tomatoes, grapes, citric fruits and wine. Medina is helpful whenever needed and efficient. He has shown himself to be responsible, well-prepared, intelligent, organized and to have very good teaching skills. Moreover, he is patient and able to solve problems calmly, but at the same time, he is enthusiastic about what he does and can transmit this enthusiasm to his colleagues. He is really a thoughtful scientist. I have now contracted him as a Postdoctoral researcher. His responsibilities include leading several master's students and he is writing several papers on the health effects of polyphenols using his method.
Full-textDOI: · Available from: Alexander Medina-Remón, Jul 02, 2015
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ABSTRACT: Tomato (Lycopersicon esculentum Mill.) is the second most important fruit crop worldwide. Tomatoes are a key component in the Mediterranean diet, which is strongly associated with a reduced risk of chronic degenerative diseases. In this work, we use a combination of mass spectrometry (MS) techniques with negative ion detection, liquid chromatography/electrospray ionization linear ion trap quadrupole-Orbitrap-mass spectrometry (LC/ESI-LTQ-Orbitrap-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) on a triple quadrupole, for the identification of the constituents of tomato samples. First, we tested for the presence of polyphenolic compounds through generic MS/MS experiments such as neutral loss and precursor ion scans on the triple quadrupole system. Confirmation of the compounds previously identified was accomplished by injection into the high-resolution system (LTQ-Orbitrap) using accurate mass measurements in MS, MS(2) and MS(3) modes. In this way, 38 compounds were identified in tomato samples with very good mass accuracy (<2 mDa), three of them, as far as we know, not previously reported in tomato samples.Rapid Communications in Mass Spectrometry 10/2010; 24(20):2986-92. DOI:10.1002/rcm.4731 · 2.64 Impact Factor
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ABSTRACT: Nutritional markers have several advantages for epidemiologic and clinical assays, when compared to dietary data obtained by food frequency questionnaires. Few studies have assessed whether total polyphenol (TP) compounds provide a valid biomarker for TP intake. To date, there has been almost no literature describing methods to determine TP in complex matrices such as urine, which have many interfering substances. We report a rapid Folin-Ciocalteu method to determine TP in urine samples using Oasis((R)) MAX 96-well plate cartridges for solid phase extraction. These plates allow analysis of a high number of samples at the same time. We performed a prospective, randomized, crossover trial and one cross-sectional study with 60 volunteers from the PREDIMED trial, seeking to evaluate whether the TP in urine were correlated with polyphenol intake and could, therefore, be considered as a marker of intake of these compounds. The assay was optimized; the sensitivity and the polarity range of urine polyphenols were increased and the detection and quantification limits were significantly reduced. The metabolites in standards solution and urine samples were stable under the storage and handling conditions. In the clinical trial and the cross-sectional study, TP excreted in spot urine samples were positively correlated with TP intake, r=0.48, P<0.01 and r=0.257, P=0.04, respectively. The methodology described may be used to detect TP in urine samples, employing the high throughput of 96-well microtiter plates and reader. The method is fast and simple and it allows analysis of a large number of samples at the same time.Analytica chimica acta 03/2009; 634(1):54-60. DOI:10.1016/j.aca.2008.12.012 · 4.52 Impact Factor
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ABSTRACT: Tomatoes and tomato-based products are rich in antioxidants such as carotenoids, vitamin C and polyphenols. The industrial processing of diced tomatoes involves heat treatments in which these antioxidant compounds may be potentially affected. In this study, we evaluate the effect of each separate step in the dice-making process. Three technological processes were investigated: Hot. Cold and Cold treated with calcium salt (CaCl2). Four stages were monitored in each process: (1) fresh tomatoes: (2) peeled tomatoes: (3) diced tomatoes; and (4) final product after sauce addition. The main tool for minimising or counteracting the eventual processing damage was the strategy of 'reconstitution', achieved by adding a sauce rich in seeds and peels with high levels of antioxidants and phenolics to the diced tomatoes. Different analyses were carried out in order to evaluate the effect of each processing step. First, total polyphenols (TP) were evaluated using Folin-Ciocalteau (F-C) assay and antioxidant activity using ABTS(+) and DPPH assays. Flavonols, flavanones, hydroxycinnamic and phenolic acids were then quantified using liquid chromatography/electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS). The combination of principal component analysis (PCA) and analysis of variance (ANOVA) revealed that each processing step induces alterations in the antioxidant and phenolic profile, and in particular sauce addition and calcium treatment significantly affected the levels of antioxidants and phenolics during the dice-making process.Food Chemistry 06/2011; 126(4):1700. DOI:10.1016/j.foodchem.2010.12.061 · 3.26 Impact Factor