Browsing by Author "Matos, Ana"
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- Amino acid contents and toxically relevant arsenic of rice varieties consumed in PortugalPublication . Rego, Andreia; Mota, Carla; Gueifão, Sandra; Ventura, Marta; Delgado, Inês; Lopes, Joel; Matos, Ana; Castanheira, IsabelThis study evaluated amino acids, antioxidant capacity, and arsenic species present in Indica and Japonica rice cultivars (Oryza sativa L.) grown in similar regions, as well as brown rice. Essential amino acids in brown rice exhibited a greater abundance when compared to white rice. Lysine was the only essential amino acid with higher concentration in white rice than in brown rice. Results showed antioxidant activity of 0.46 IC50 (mg mL 1) and TPC 0.11 mg eq. GA/g of sample. Total arsenic content in rice samples was about 200 mg/kg. HPLC-ICP-MS determinations revealed iAs as the predominant species in bran samples. Through Spearman’s correlation, negative correlations between six amino acids and total arsenic content in japonica white rice were observed. Sulphur amino acid cysteine presented the highest negative correlation (q = 0.758, p-value = 0.011). Based on our results, a regular benefit-risk assessment for rice products to enhance the consumption choice is recommended.
- Análise multielementar e quimiometria na autenticidade de alimentos: Pera RochaPublication . Coelho, Inês; Matos, Ana; Teixeira, Rita; Nascimento, Ana; Bordado, João; Donard, Olivier; Castanheira, IsabelA combinação da análise multielementar com a técnicas de quimiometria utilizadas permitiu agrupar as amostras de acordo com a sua região de origem, contribuindo para a sua autenticidade assim como para um maior conhecimento da sua composição nutricional.
- A classification system to assist compilers in the evaluation of digestion methods for the determination of mineral contents in pseudocerealsPublication . Nascimento, Ana; Motta, Carla; Santos, Mariana; Santiago, Susana; Rego, Andreia; Delgado, Inês; Matos, Ana; Namorado, Sónia; Castanheira, IsabelPlant based diet pseudocereals, as quinoa, amaranth and buckwheat, are a rich source of minerals that gained increasing attention of scientific community, especially due to their high nutritional value and health benefits. A rigorous analytical determination is necessary to guarantee an estimation of dietary intake as close as possible of real mineral intake. Reliable food composition data is a crucial tool to avoid incorrect estimation of mineral deficiency. Previously to analysis, a sample decomposition is required, which, can be undertaken by different digestion methods. The destruction of organic matter is a slow step of the overall analytical process mostly dependent on the content of significant components. Although due to the lack of certified reference materials for pseudocereals analysis, little information is available to assist compilers and analysts in selecting or comparing the adequacy of digestion method for mineral determination. This work aimed to identify the suitable digestion method for accurate determination of Cu, Mn, Fe, Zn, Mg, P, Ca, K and Na in pseudocereals assessing in terms of accuracy and precision framed by a quality system. Analysis, were performed according with ISO 17025. Mineral levels obtained, by ICP-OES, with the three procedures were compared. The adequacy of digestion methods to assist instrumental analysis on determination of mineral contents was score based on three categories of method performance: limit of detection, uncertainty and statistical comparability test. A classification system was rated based on method performance: the digestion method was rejected if results failed in two categories, classified as “use with caution” if results were not satisfactory in one category or accepted if the results passed in all the categories. All the methods were adequate for the determination of Mg and P. It was possible to obtain comparable results, with caution, from all digestion methods. This classification system is a useful and pioneer effort to assist compilers and analysts to scrutinize pseudocerals mineral analysis.
- Impacto do processo culinário no teor de minerais de pseudocereaisPublication . Mota, Carla; Nascimento, Ana; Santos, Mariana; Delgado, Inês; Matos, Ana; Torres, D.; Castanheira, IsabelIntrodução: Recentemente a Organização Mundial de Gastroenterologia incluiu os pseudocereais na dieta dos doentes celíacos. Esta escolha é suportada pelo elevado teor proteico, vitamínico e mineral que este grupo de alimentos apresenta. Porém, a literatura é escassa sobre o efeito do processamento culinário no teor nutricional dos pseudocerais. Objetivo: Avaliar o efeito do tratamento culinário, no perfil de minerais de pseudocerais expresso em taxa de retenção do nutriente (TRN) Métodos: Amostras de quinoa, amaranto e trigo-sarraceno foram aleatoriamente adquiridas em supermercados de representação nacional e submetidas a três tratamentos culinários: cozido em água e a vapor e tostado. O teor dos minerais cálcio, magnésio, sódio, potássio, fósforo, ferro, zinco, cobre e manganês foi determinado, por ICP-OES, nos pseudocereais antes e depois de cozinhados. A TRN foi calculada por nutriente e por tratamento culinário sendo expressa pelo rácio percentual entre o teor do nutriente no alimento cozinhado e o teor do nutriente no alimento cru, para quantidades iguais de alimento. Resultados: O perfil mineral do trigo-sarraceno não foi afetado em nenhum dos tratamentos culinários, registando-se TRN superiores a 92%. No amaranto a perca mais acentuada foi observada no magnésio (6%) no amaranto cozido. Os processamentos culinários da quinoa conduziram a reduções nos teores de todos os minerais estudados, sendo a TRN mais baixa (70%) encontrada para fósforo na quinoa cozida. Nos ensaios realizados, não se observaram percas acentuadas de minerais, sendo concordantes com os resultados publicados na literatura, para outros alimentos. Conclusões: Os resultados evidenciam a existência de variabilidade na taxa de retenção em função do processo culinário. O conhecimento da TRN especifica por mineral, alimento e tratamento é uma indicação muito útil para cálculo da composição nutricional das dietas dos doentes celíacos e de outros indivíduos que necessitam de intervenção dietética. Os pseudocereais processados são uma fonte importante de nutrientes, e uma excelente alternativa nutricional, para a população em geral.
- Network biology approaches in the identification of novel pharmacological targets – the case of cystic fibrosisPublication . Loureiro, Cláudia; Matos, Ana; Santos, João; Farinha, Carlos; Jordan, Peter; Matos, Paulo; Pinto, FranciscoIn cystic fibrosis, the most common disease-causing mutation is F508del, which causes not only intracellular retention and degradation of CFTR, but also defective channel gating and decreased membrane stability of the small amount that reaches the plasma membrane (PM). Thus, pharmacological correction of mutant CFTR requires targeting of multiple cellular defects in order to achieve clinical benefit. Although small-molecule compounds have been identified and commercialized that can correct its folding or gating, an efficient retention of F508del CFTR at the PM has not yet been explored pharmacologically despite being recognized as a crucial factor for improving functional rescue of chloride transport. In ongoing efforts to determine the CFTR interactome at the PM, we used three complementary approaches: targeting proteins binding to tyrosine-phosphorylated CFTR, protein complexes involved in cAMP-mediated CFTR stabilization at the PM, and proteins selectively interacting at the PM with rescued F508del-CFTR but not wt-CFTR. Using co-immunoprecipitation or peptide–pull down strategies, we identified around 400 candidate proteins through sequencing of complex protein mixtures using the nano-LC Triple TOF MS technique. Key candidate proteins were validated for their robust interaction with CFTR-containing protein complexes and for their ability to modulate the amount of CFTR expressed at the cell surface of bronchial epithelial cells. Here, we describe how we explored the abovementioned experimental datasets to build a protein interaction network with the aim of identifying novel pharmacological targets to rescue CFTR function in cystic fibrosis (CF) patients. We identified and validated novel candidate proteins that were essential components of the network but not detected in previous proteomic analyses.
- Optimizing UPLC isocyanate determination through a Taguchi experimental design approachPublication . André, Catarina; Jorge, Fabiana; Castanheira, Isabel; Matos, AnaThe development of a chromatographic procedure for an ultra-performance liquid chromatography can be a very time-consuming task, as the general approach for finding the appropriate operating conditions has been a trialand- error process. The present study reports a novel approach in the field of ultra-performance liquid chromatography by using statistical experimental design based on Taguchi’s method, which allows a complete separation of nine isocyanates present in a complex matrix. The resolution between two adjacent peaks was considered as a quality characteristic and transformed to a Taguchi signal-to-noise ratio. An orthogonal array L9 (34) was selected to analyze the effect of four chromatographic factors, that is, proportion of solvent, percent triethylamine (v/v), temperature ( C), and flow (mLmin 1), with three levels each. The joint analysis performed to the significant factors achieved in the eight analyses of variance allowed to identify two methods to conduct a complete separation of all peaks. Six isocyanates were separated with the first method, with all factors at the lowest level. The remaining three isocyanates were separated with the second method, with the proportion of solvent at the highest level and the other factors at the lowest level. The overall Taguchi experimental design identified the proportion of solvent and the flow rate as major chromatographic factors. Finally, confirmatory experiments were performed with samples prepared with six and three isocyanates, confirming the complete separation of all isocyanates in the study. The Taguchi methods provided a systematic and efficient methodology for this optimization, with considerably less effort than would be required for other optimizations techniques.
- Protein content and amino acids profile of pseudocerealsPublication . Motta, Carla; Santos, Mariana; Mauro, Raul; Matos, Ana; Torres, Duarte; Castanheira, IsabelQuinoa (Chenopodium quinoa), amaranth (Amaranthus caudatus) and buckwheat (Fagopyrum esculentum) represent the main protein source in several diets, although these pseudocereals are not currently present in the FCDB nutrient profile information. The aim of this work is to characterise the AA profile of these pseudocereals and compare them with rice. Total protein content revealed to vary from 16.3 g/100 g (quinoa Salta) to 13.1 g/100 g (buckwheat) and lower values were found in rice samples (6.7 g/100 g). For pseudocereals the most abundant essential AA was leucine. Quinoa-Salta evidences the highest leucine content (1013 mg/100 g) and the minor methionine content (199 mg/100 g). Buckwheat was the cereal with the highest phenylalanine content (862 mg/100 g). Rice (Oryza sativa) presents the lowest content for all AA. Results showed pseudocereals as the best source of AA. EuroFIR guidelines where strictly followed and proved to be a crucial tool to guarantee data interchangeability and comparability.
- Tracing the geographical origin of PDO products with multielement fingerprinting and chemometrics: The case of Rocha pearPublication . Coelho, Inês; Matos, Ana; Teixieira, Rita; Nascimento, Ana; Bordado, João; Donard, Olivier; Castanheira, IsabelThis work aims at promoting the Protected Designation of Origin "Pera Rocha do Oeste" by providing a method to identify the geographical origin of this traditional Portuguese food commodity.