2013 - Strategic Project

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Publications

Analysis of volatile human urinary metabolome by solid-phase microextraction in combination with gas chromatography–mass spectrometry for biomarker discovery: application in a pilot study to discriminate patients with renal cell carcinoma

Publication . Monteiro, Márcia; Carvalho, Márcia; Henrique, Rui; Jerónimo, Carmen; Moreira, Nathalie; Bastos, Maria de Lourdes; Guedes de Pinho, Paula

A new and simple analytical approach consisting of headspace-solid phase microextraction (HS-SPME) sampling coupled with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed to study the volatile human urinary metabolome. A central composite design (CCD) was used in the optimisation of extraction conditions. Fibre selection and evaluation of pH influence were performed using an univariate mode and the influence of other parameters, such as the time and temperature of extraction, time of incubation and salt addition, that affect the efficiency of the SPME sampling, was carried out using a CCD. With a sample volume of 2 mL, the optimal conditions in terms of total response values and reproducibility were achieved by performing analyses with a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre, in an acidic pH (pH 2) with the addition of 0.59 g of NaCl, allowing the sample to equilibrate for 9 min and extracting at 68 °C for 24 min. The applicability of the optimised method was then tested in a pilot non-target analysis of urine samples obtained from patients with renal cell carcinoma (RCC) and healthy individuals. Chemometric unsupervised analyses performed on the volatile pattern acquired for these samples clearly showed the potential of volatile urinary metabolome to discriminate between RCC and control patients.

2014Journal article

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Chiral enantioresolution of cathinone derivatives present in “legal highs”, and enantioselectivity evaluation on cytotoxicity of 3,4-methylenedioxypyrovalerone (MDPV)

Publication . Silva, Bárbara; Fernandes, Carla; Tiritan, Maria Elizabeth; Pinto, Madalena M.M.; Valente, Maria João; Carvalho, Márcia; Guedes de Pinho, Paula; Remião, Fernando

Recently, great interest has been focused on synthetic cathinones since their consumption has increased exponentially. All synthetic cathinones exist as chiral molecules; the biological and/or toxicological properties of cathinones generally differ according to the enantiomers in human body. In this study, a chiral liquid chromatography method was developed to separate and determine the enantiomeric ratio of synthetic cathinones present in "legal highs" acquired in old smart shops or over the Internet. All the synthetic cathinones were efficiently enantio-separated with α and Rs ranging from 1.24 to 3.62 and from 1.24 to 10.52, respectively, using polysaccharide-based chiral stationary phases. All synthetic cathinones, with the exception of 4-methylethcathinone (4-MEC), were present in the commercialized "legal highs" in an enantiomeric proportion of 50:50. One of the studied chiral compounds was 3,4-methylenedioxypyrovalerone (MDPV), one of the most consumed cathinone derivative worldwide. Our research group has recently reported its hepatotoxicity in the racemic form. Thus, the analytical enantioresolution of the MDPV was scaled up to multi-milligram using a semi-preparative amylose tris-3,5-dimethylphenylcarbamate column (20 cm × 7.0 mm ID, 7 µm particle size). Both enantiomers were isolated with high enantiomeric purity (enantiomeric excess > 99 %). The toxicity of S-(-)-MDPV and R-(+)-MDPV was evaluated, for the first time, using primary cultures of rat hepatocytes. It was also possible to verify that MDPV enantiomers showed hepatotoxicity in a concentration-dependent manner, but displayed no enantioselective toxicity in this cell culture model.

2016Journal article

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Potentiality of volatile organic compounds to discriminate patients with cancer by using chemometric tools

Publication . Monteiro, Márcia Sá; Carvalho, Márcia; Bastos, Maria de Lourdes; Guedes de Pinho, Paula

Metabolomics for the diagnosis of tumor and monitoring treatment is a promising concept since tumor metabolism markedly differs from the metabolism of normal cells. By monitoring changes in metabolite levels, we might be able to detect cancer and better understand cancer pathological processes and progression.Untargeted metabolomics provides an enormous volume of data that cannot be manually analyzed. Thus, before data analysis, NMR and MS spectra must be corrected for all variation caused by experimental variables. This is a critical part in the data mining process as it can drastically interfere with the next step – multivariate statistical analysis (chemometrics). In this review, we will focus on the potentialities of volatile organic compounds (VOCs) to discriminate patients with cancer. For this purpose,we will describe, first, data mining and extracting performed before NMR and MS data analysis. Furthermore, chemometric tools used for pattern recognition and statistical analysis will be described.

2015Journal article

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