Browsing by Author "Pereira, Carla"
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- Aesculus hippocastanum L.: a simple ornamental plant or a source of compelling molecules for industry?Publication . Dridi, Asma; Reis, Filipa S.; Pires, Tânia C.S.P.; Calhelha, Ricardo C.; Pereira, Carla; Zaghdoudi, Khalil; Ferreira, Isabel C.F.R.; Barros, Lillian; Barreira, João C.M.Aesculus hippocastanum L., also known as horse chestnut, is an ornamental tree whose seeds are mostly discarded in landfills in the regions where they are grown. However, recent studies have shown that these seeds can be a source of interesting compounds for several industries. This work aimed to chemically characterize horse chestnut seeds at the level of compounds recognized for their wide bioactivity, i.e., organic acids, including phenolic compounds, using chromatographic methodologies (UFLC-DAD and LC-DAD-ESI/MSn). In addition, the bioactivity of these seeds was evaluated by in vitro methodologies, seeking to relate the respective (bio)activity to the compounds present in the endocarp (husk), seed coat (skin), and peeled seed (pulp). The antioxidant activity (lipid peroxidation inhibition and oxidative haemolysis inhibition), antibacterial potential (against Gram-positive and Gram-negative bacteria) and cytotoxicity (in human tumour cell lines and porcine liver primary cells) were evaluated. Kaempferol-O-pentoside-O-hexoside-O-hexoside was the main phenolic identified in the pulp. At the same time, (-)-epicatechin and beta-type (epi)catechin dimer were the major phenolics present in husk and skin, respectively. In general, A. hippocastanum extracts presented antioxidant and antibacterial potential, without toxicity up to the maximal tested dose. Overall, these findings anticipate potential applications of A. hippocastanum seeds in food- or pharmaceutical-related uses.
- Alcachofra, borututu e cardo mariano: compostos bioativos, propriedades antioxidantes e hepatotoxicidade de infusões e suplementos dietéticosPublication . Pereira, Carla; Barros, Lillian; Calhelha, Ricardo C.; Ferreira, Isabel C.F.R.A alcachofra (Cynara scolymus L.), o borututu (Cochlospermum angolensis Welw.) e o cardo mariano (Silybum marianum (L.) Gaertn) são três plantas muito conhecidas pelo seu valor nutricional e utilizadas na medicina tradicional pelas suas propriedades antioxidantes e hepatoprotetoras [1-3]. No presente trabalho, estudaram-se infusões e suplementos dietéticos (na forma de comprimidos) das três plantas com o intuito de avaliar os seus compostos bioativos (fenóis e flavonóides totais), a atividade antioxidante (atividade captadora de radicais livres, poder redutor e inibição da peroxidação lipídica), a atividade anti-tumoral (linha de células tumorais humanas HepG2- carcinoma hepatocelular) e a hepatotoxicidade em culturas primárias células de fígado de porco- PLP2). Todas as amostras revelaram propriedades antioxidantes com valores de EC50 inferiores à dose diária recomendada, mas as infusões revelaram melhores resultados que os suplementos dietéticos. A infusão de borututu apresentou a melhor atividade antioxidante (EC50 ≤ 170 μg/mL) e também mostrou atividade anti-tumoral (GI50 = 146 μg/mL) sem toxicidade para células de fígado não tumorais (GI50 > 400 μg/mL). Por sua vez, o respetivo suplemento dietético não revelou actividade anti-tumoral. A infusão de alcachofra apresentou o melhor valor de atividade anti-tumoral na linha de carcinoma hepatocelular (GI50 = 52 μg/mL), mas com toxicidade para células normais de fígado (GI50 = 72 μg/mL). As propriedades bioativas das infusões e suplementos dietéticos foram, na sua maioria, positivamente correlacionadas (p < 0.05) com o conteúdo em fenóis e flavonóides totais.
- Análise cromatográfica da composição química de conservas à base de trigoPublication . Novais, Cláudia; Pereira, Carla; Rodriguez, L.Á.; Antón, M.B.; Barros, LillianA importância de uma dieta variada para a saúde, prevenindo doenças e/ou deficiência de nutrientes é incontestável1. Embora o consumo de alimentos frescos seja altamente recomendado, muitas vezes não é possível, e os alimentos enlatados são uma opção para a sua substituição, ajudando a garantir a ingestão necessária de nutrientes que devem ser ingeridos diariamente2. No presente estudo, dois produtos em conserva de trigo germinado foram caracterizados por cromatografia em termos da sua composição em ácidos gordos (GC-FID) e em açúcares livres (HPLCRI). Um dos produtos continha trigo orgânico germinado e alho preto, e o outro trigo orgânico germinado, cebola, abóbora, cenoura, pimentão vermelho, nabo e alho. Ambos continham caldo vegetal. Relativamente aos ácidos gordos, para ambas as amostras, o ácido oleico foi o que mais se destacou, seguido do ácido linoleico (Fig. 1, à esquerda). Em termos de açúcares livres, a maltose foi o açúcar mais abundante em ambas as amostras e a sacarose e a frutose foram detetados em menores quantidades na conserva de trigo e alho preto e na de trigo e vegetais, respetivamente (Fig. 1, à direita). Em conclusão, estas conservas de trigo germinado mostraram uma composição química importante para a manutenção de uma dieta variada e equilibrada.
- Análise cromatográfica de ácidos orgânicos em cogumelos silvestres comestíveis do Nordeste de Portugal: validação de uma técnica de UFLC-PDAPublication . Barros, Lillian; Pereira, Carla; Ferreira, Isabel C.F.R.Na Península Ibérica as verduras (silvestres ou tradicionalmente cultivadas) têm sido alimentos importantes na dieta humana. O valor nutricional de verduras e os seus benefícios para a saúde têm sido reconhecidos como importantes alvos de investigação. Os grelos, inflorescências da couve-nabo (Brassica napus L. var. napus) e os espigos, inflorescências da couve-tronchuda (Brassica oleracea L. var. costata DC.) são exemplos de espécies tradicionalmente cultivadas e amplamente consumidas nas regiões do Norte de Portugal. Neste trabalho, avaliou-se a composição nutricional e o potencial nutracêutico, nomeadamente antioxidante, das espécies mencionadas anteriormente. O valor nutricional foi determinado através dos índices de lípidos, proteínas, cinzas e glúcidos, tendo sido também calculado o seu valor energético. A caracterização nutracêutica incluiu a determinação de antioxidantes hidrofílicos (ácido ascórbico, fenóis, flavonóides e açúcares), lipofílicos (carotenóides, clorofilas, tocoferóis e ácidos gordos). As propriedades antioxidantes foram avaliadas por métodos químicos e bioquímicos [1]. As duas variedades de Brassica estudadas mostraram ser verduras nutricionalmente equilibrados, em particular os espigos que mostraram conter teores mais elevados de humidade, proteínas, energia, lípidos, β-caroteno e vitamina C. Os grelos revelaram maiores teores de cinzas, glúcidos totais, açúcares livres (incluindo frutose, glucose, sacarose e rafinose), ácido gordo n-3 essencial, ácido α- linolénico, as melhores razões PUFA/SFA e ácidos gordos n-6/n-3, tocoferóis, licopeno, clorofilas, fenóis, flavonóides, apresentando também mais propriedades antioxidantes. Os benefícios para a saúde inerentes ao consumo destas duas espécies estão associados às suas propriedades antioxidantes, reforçando desta forma, a sua inclusão em dietas saudáveis e equilibradas. Este trabalho enfatiza o interesse do consumo de espécies tradicionais, validando a sua utilização empírica, mas também conferindo valor acrescentado a estes produtos, incluídos desde há longa data no receituário gastronómico regional.
- Análise cromatográfica de ácidos orgânicos em cogumelos silvestres comestíveis do Nordeste de Portugal: validação de uma técnica de UFLC-PDAPublication . Barros, Lillian; Pereira, Carla; Ferreira, Isabel C.F.R.Os cogumelos são uma excelente fonte de compostos antioxidantes nomeadamente tocoferóis, ácido ascórbico, carotenóides, compostos fenólicos e ácidos orgânicos. Estes últimos compostos desempenham um papel importante na manutenção da qualidade e características organoléticas de frutos e vegetais e, por isso, têm sido utilizados no controlo de qualidade dos mesmos. A natureza e a concentração dos ácidos orgânicos são também fatores importantes no sabor dos cogumelos. Mas, alguns deles (p. ex. ácidos tartárico, málico, cítrico ou succínico) podem também desempenhar um papel protetor contra várias doenças crónicas devido às suas propriedades antioxidantes, quelatando metais ou deslocalizando a carga eletrónica de radicais livres. Neste trabalho, avaliaram-se os perfis em ácidos orgânicos de diferentes espécies de cogumelos comestíveis do Nordeste de Portugal, após extração com ácido metafosfórico e análise por cromatografia líquida ultra rápida e deteção por fotodiodos (UFLC-PDA). A separação cromatográfica dos compostos foi conseguida com uma coluna de C18 em fase reversa SphereClone (Phenomenex) e eluição isocrática com ácido sulfúrico (3,6 mM) a um caudal de 0,8 mL/min. Todos os compostos foram separados em 8 minutos. A validação do método de análise foi feita com uma amostra de Agaricus bisporus e provou ser reprodutível e preciso. Os perfis de ácidos orgânicos obtidos foram similares para todas as espécies de cogumelos estudadas: os principais ácidos orgânicos encontrados foram os ácidos oxálico, málico e fumárico; algumas espécies apresentaram também os ácidos quínico e cítrico. Sarcodon imbricatus foi a espécie que revelou uma maior concentração de ácidos orgânicos (254,09 mg/g massa seca), enquanto a espécie Bovista nigrescens apresentou a concentração mais baixa (1,33 mg/g). O elevado teor de ácidos orgânicos encontrado pode sugerir que estes compostos podem estar relacionadas com a atividade antioxidante destas espécies já descrita na literatura, nomeadamente pelo nosso grupo de investigação.
- Analysis of phenolic compounds in Cynara scolymus L. and Silybum marianum (L.) Gaertn. by HPLC-DAD-ESI/MSPublication . Pereira, Carla; Barros, Lillian; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.Cynara scolymus L. (artichoke) and Silybum marianum (L.) Gaertn. (milk thistle) are medicinal plants native to the Mediterranean Basin that belong to the Asteraceae family. The flowers and leaves of milk thistle are used in the treatment of liver, spleen and gallbladder disorders [1] and artichoke leaves are used for their cholagogue, choleretic and choliokinetic actions, and also for treatment of dyspepsia and as antidiabetics [2]. The beneficial properties of medicinal plants can be related to their large diversity of phytochemicals, among which phenolic compounds are outstanding. Thereby, the aim of the present work was to obtain and compare the phenolic profiles of artichoke and milk thistle aqueous (prepared by infusion) and hydromethanolic (maceration in methanol: water 80:20, v/v) extracts, using HPLC-DAD-ESI/MS. The aqueous extract of artichoke presented higher concentration in total phenolic compounds (15.29 mg/g extract) than the hydromethanolic extract (4.37 mg/g) with slight differences between the respective profiles; the major flavonoid found in the aqueous and hydromethanolic extract was luteolin-7-O-glucuronide (5.64 and 0.70 mg/g, respectively), followed by luteolin-7-O-glucoside (2.88 and 0.49 mg/g, respectively). Monocaffeoylquinic acid derivatives were only present in the hydromethanolic extract, being 5-O-caffeoylquinic acid (0.49 mg/g) the most abundant one, while dicaffeoylquinic acid derivatives were mostly identified in the aqueous extract; 1,3-O-dicaffeoylquinic acid was the most abundant one in both extracts (0.90 and 0.37 mg/g in the aqueous and hydromethanolic extract, respectively). Regarding to milk thistle preparations, similar phenolic profiles were observed, with only quantitative differences between them. The aqueous extract revealed a higher phenolic compounds concentration (5.57 mg/g) than the hydromethanolic extract (3.56 mg/g), with apigenin-7-O-glucuronide as the major compound in both preparations (3.14 mg/g in the aqueous extract, and 0.58 mg/g in the hydromethanolic extract). Total flavonoids were higher in the aqueous extract (4.66 mg/g), with apigenin-7-Oglucuronide, luteolin-7-O-glucuronide (1.17 mg/g), and apigenin-O-deoxyhexosylglucuronide (0.36 mg/g) as the main constituents. The phenolic acids found in the hydromethanolic extract (total content 1.65 mg/g), included 5-O-caffeolyquinic and protocatechuic acids (0.56 and 0.44 mg/g, respectively). Besides these phenolic acids, the hydromethanolic extract also revealed high levels of luteolin-7-O-glucuronide (0.58 mg/g). Overall, aqueous extracts presented higher phenolic contents than their hydromethanolic extracts in both species, which could be related with the heat treatment to which infusions were subjected.
- Analytical tools used to distinguish chemical profiles of plants widely consumed as infusions and dietary supplements: artichoke, milk thistle and borututuPublication . Pereira, Carla; Barros, Lillian; Ferreira, Isabel C.F.R.Artichoke, borututu and milk thistle are three medicinal plants widely consumed as infusions or included in dietary supplements (e.g., pills and syrups). Despite their high consumption, studies on nutritional value and primary metabolites are scarce, being only reported the composition in secondary metabolites such as phenolic compounds. Therefore, their nutritional value was assessed and analytical tools (liquid and gas chromatography coupled to different detectors) were used to distinguish the chemical profiles namely in hydrophilic (sugars and organic acids) and lipophilic (fatty acids and tocopherols) compounds. Chromatographic techniques are important analytical tools used in the identification and quantification of several molecules, also being a standard requirement to distinguish different profiles. Borututu gave the highest energetic value with the highest content of carbohydrates and fat, sucrose and total sugars, shikimic and citric acids, α-, β-, δ- and total tocopherols. Artichoke had the highest ash and protein contents, oxalic acid, SFA (mainly palmitic acid acid), and γ-tocopherol, as also the best n6/n3 ratio. Milk thistle showed the highest levels of fructose and glucose, quinic acid and total organic acids, PUFA, mainly linoleic acid, and the best PUFA/SFA ratio. The hydrophilic compounds identified in the studied plants, mostly sugars, are the responsible for the energetic contribution of their widely consumed infusions. Otherwise, the bioactivity of lipophilic compounds namely, unsaturated fatty acids and tocopherols, is lost in those preparations but can be recovered in dietary supplements based on the plants. As far as we know this is the first report on detailed composition of molecules with nutritional features.
- Anthocyanin-rich extract obtained from Prunus Spinosa L. by ultrasound assisted extraction for coloring purposesPublication . Leichtweis, Maria Gabriela; Pereira, Carla; Prieto Lage, Miguel A.; Alves, Maria José; Calhelha, Ricardo C.; Barreiro, M.F.; Baraldi, Ilton J.; Ferreira, Isabel C.F.R.; Barros, LillianAnthocyanins are a group of natural pigments presenting a range of colours between red, blue, and violet that are characteristic of various fruits and vegetables. A complex profile of anthocyanins, predominantly cyanidin 3-rutinoside and peonidin 3-rutinoside, was previously identified in Prunus spinosa L. fruit, a bitter and astringent fruit from a wild shrub that is poorly commercially exploited [1]. In this sense, the objective of this work was to develop a natural food colourant based on anthocyanins extracted from the epicarp of P. spinosa fruits. For that purpose, a conventional extraction method, maceration, and a rapid and low-cost ultrasound procedure were applied for the extraction of anthocyanins from this matrix. To achieve the conditions that maximize anthocyanins’ extraction, a response surface methodology was applied using a circumscribed central composite design with three variables and five levels, being the variables time, temperature, and ethanol content, in the case of maceration extraction, whereas for ultrasound assisted extraction, temperature was replaced by ultrasound power. The anthocyanins were identified and quantified by HPLC-DAD-ESI/MS. The optimized extract was assessed in terms of antioxidant and antimicrobial capacity, and hepatotoxicity. Ultrasound assisted extraction was the most efficient method, under optimum conditions of 5.00±0.15 min, 400.00±32.00 W and 47.98±2.88% ethanol, where the extraction yield was 68.60±2.06% (v/v), with a total anthocyanin content of 18.17±1.82 mg/g of dry extract and 11.76±0.82 mg/g of dry epicarp. Regarding bioactivity, the optimized extract showed antioxidant and antimicrobial activity and it did not show hepatotoxic effects in a primary culture of porcine liver cells. To validate its coloring properties, the anthocyanin-rich extract was incorporated into a typical Brazilian confectionery product "beijinho", proving its applicability as food colorant.
- Anthocyanins from rubus fruticosus l. And morus nigra l. applied as food colorants: a natural alternativePublication . Vega, Erika N.; Molina, Adriana K.; Pereira, Carla; Dias, Maria Inês; Heleno, Sandrina A.; Rodrigues, Paula; Fernandes, Isabel P.; Barreiro, M.F.; Stojković, Dejan; Soković, Marina; Carocho, Márcio; Barreira, João C.M.; Ferreira, Isabel C.F.R.; Barros, LillianGiven the importance of colour in the general acceptance or rejection of a product, the use of colorants is a widespread practice, particularly in the food industry. At the same time, with the increasing consumers’ awareness of the health effects that some artificial colorants can exert, there is a growing tendency to prioritize foodstuffs containing natural additives. In this work, Morus nigra L. and Rubus fruticosus L. fruit juices were characterized in terms of anthocyanins, organic acids, free sugars, and tocopherols, as also regarding their bioactive properties. Given their richness in anthocyanins, this study also aimed to prepare different solid colouring formulations by the spray-drying technique, using as stabilizers maltodextrin and arabic gum. Six free sugars and two organic acids were detected in the fruit juices, as well as the four tocopherol isoforms. Two cyanidin derivatives were found in M. nigra (cyanidin-3-O-glucoside and cyanidin-O-rhamnoside) and other four in R. fruticosus (cyanidin-O-hexoside, cyanidin-3-O-glucoside, cyanidin-O-pentoside, and cyanidin-3-O-dioxaloilglucoside). The developed colouring formulations revealed a good stability over time, in terms of anthocyanin concentration and colour parameters, and revealed to be safe for consumption, either concerning their low microbial load and lack of cytotoxicity. Thus, they represent a promising natural alternative to the massively used artificial colorants.
- Antioxidant activity and nutritional value of Mentha spicata L.: a comparison between reserve and standard lotsPublication . Rita, Íngride; Heleno, Sandrina A.; Martins, Natália; Pereira, Carla; Barros, Lillian; Ferreira, Isabel C.F.R.Currently, the consumption of tea and herbal infiisions is increasing só much that its daily worldwide consumption is evaluated in more than three million cups. Therefore, in a competitive and sophisticated sector as the tea market, the innovation and development of new products is imperative (Hicks, 2009; Li et al., 2013). Nowadays, we have at our disposal a new range of emerging products, such as the designated "reserve lots" exclusively prepared by using the younger parts (apical leaves) ofthe plant collected in the hot summer months; the standard lots do not have these harvest specific requirements. In this perspective, the present study was accomplished to understand the differences between two lots of Mentha spicata L. (spearmint) for infusion preparation, widely used due to its exquisite and outstanding flavour, as well as for its antioxidant properties (Goméz-Prieto et al., 2007). The nutritional value, the energetic contribution, and the antioxidant activity, as well as the bioactive compounds (phenolics and flavonoids) content of both standard and reserve lots, were evaluated. The nutritional value was determined through the infüsion sugars content, once these were the only nutrients present in the preparations; the analysis was carried out by high performance liquid chromatography coupled to a refraction index detector (HPLC-RI). The presence of fmctose, glucose and sucrose was detected in very low concentrations on both infüsions, with the reserve lot revealing slightly higher amounts. Sucrose was the most abundant sugar, present in a concentoration of 5.9 mg/100 mL in the standard lot and 8.4 mg/100 mL in the reserve lot. Total sugars and energy were 13.2 mg/100 mL and 53 cal/100 mL, respectively, in the standard lot; and 16.9 mg/100 mL and 67.4 cal/100 mL, respectively, in the reserve lot. The antioxidant activity of the infüsions was assessed by different assays (free radicais scavenging activity, reducing power and lipid peroxidation inhibition), whereas total phenolics and flavonoids were estimated by colorimetric assays. The reserve lot presented the lowest EC50 values, corresponding to a higher antioxidant activity, in ali the assays performed (152 to 336 |ig/mL), in comparison to the standard lot (173 to 546 |^g/mL). Both the iníüsions revealed higher potential in lipid peroxidation inhibition, in concentrations of 173 (standard tot) and 152 [ig/mL (reserve lot), followed by reducing power (301 and 198 l^g/mL, respectively) and free radicais scavenging activity (546 and 336 |^g/mL, respectively). In agreement with the antioxidant activity results, the amounts of total phenolics and flavonoids were higher in the reserve lot (2. 86 and 0.378 mg gallic acid equivalents- GAE/mL) when compared to the standard lot (1. 83 and 0.268 mg GAE/mL). Overall, in our perspective, these results represent a major contribution to elucidate the consumer about the bioactive effects of new emerging tea products such as reserve lots, which actually showed a higher antioxidant activity.