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- Optimization of heat- and ultrasound-assisted extraction of anthocyanins from Hibiscus sabdariffa calyces for natural food colorantsPublication . Pinela, José; Prieto Lage, Miguel A.; Pereira, Eliana; Jabeur, Inès; Barreiro, M.F.; Barros, Lillian; Ferreira, Isabel C.F.R.calyces. The extraction variables, time (t), ethanol proportion (S), and temperature (T) or ultrasonic power (P), were combined in a 5-level experimental design and analysed by response surface methodology for process optimization. The delphinidin-3-O-sambubioside (C1) and cyanidin-3-O-sambubioside (C2) levels were monitored by LC-DAD-ESI/MSn and used as response criteria. The developed models were successfully fitted to the experimental data and used to determine optimal extraction conditions. UAE was the most efficient method yielding 51.76 mg C1+C2/g R under optimal conditions (t=26.1 min, P=296.6W and S=39.1% ethanol, v/ v). The dose-response effects of the solid/liquid ratio on the extraction rate were also determined. The anthocyanin levels herein reported are higher than those found in the literature, which support the potential use of H. sabdariffa as a sustainable source of natural colorants with application in different industrial sectors.
- HPLC-DAD-ESI/MS phenolic characterization and biological activity of Equisetum giganteum L.Publication . Jabeur, Inès; Martins, Natália; Barros, Lillian; Calhelha, Ricardo C.; Vaz, Josiana A.; Achour, Lotfi; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.Naturally-occurring phytochemicals have received a pivotal attention in the last years, due to the increasing evidences of biological activities. Equisetum giganteum L., commonly known as “giant horsetail”, is a native plant from Central and South America, being largely used in dietary supplements as diuretic, hemostatic, antiinflammatory and anti-rheumatic agents [1,2]. The aim of the present study was to evaluate the antioxidant (scavenging effects on 2,2-diphenyl-1-picrylhydrazyl radicals- RSA, reducing power- RP, β-carotene bleaching inhibition- CBI and lipid peroxidation inhibition- LPI), anti-inflammatory (inhibition of NO production in lipopolysaccharidestimulated RAW 264.7 macrophages) and cytotoxic (in a panel of four human tumor cell lines: MCF-7- breast adenocarcinoma, NCI-H460- non-small cell lung cancer, HeLa- cervical carcinoma and HepG2- hepatocellular carcinoma; and in non-tumor porcine liver primary cells- PLP2) properties of E. giganteum, providing a phytochemical characterization of its extract (ethanol/water, 80:20, v/v), by using highperformance liquid chromatography coupled to diode array detection and electrospray ionisation mass spectrometry (HPLC-DAD–ESI/MS). E. giganteum presented fourteen phenolic compounds, two phenolic acids and twelve flavonol glycoside derivatives, mainly kaempferol derivatives, accounting to 81% of the total phenolic content, being kaempferol-O-glucoside-O-rutinoside, the most abundant molecule (7.6 mg/g extract). The extract exhibited antioxidant (EC50 values = 123, 136, 202 and 57.4 μg/mL for RSA, RP, CBI and LPI, respectively), anti-inflammatory (EC50 value = 239 μg/mL) and cytotoxic (GI50 values = 250, 258, 268 and 239 μg/mL for MCF-7, NCI-H460, HeLa and HepG2, respectively) properties, which were positively correlated with its concentration in phenolic compounds. Furthermore, up to 400 μg/mL, it did not revealed toxicity in non-tumor liver cells. Thus, this study highlights the potential of E. giganteum extracts as rich sources of phenolic compounds that can be used in the food, pharmaceutical and cosmetic fields.
- Bioactive properties and functional constituents of Hypericum androsaemum L.: A focus on the phenolic profilePublication . Jabeur, Inès; Tobaldini, Flávia; Martins, Natália; Barros, Lillian; Martins, Ivone; Calhelha, Ricardo C.; Henriques, Mariana; Silva, Sónia; Achour, Lotfi; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.Hypericum androsaemum L. ethanol:water extract acted as a lipid peroxidation inhibitor and free radical scavenger. Amarked inhibition of the growth of breast, lung, cervical and hepatocellular human carcinoma cell lineswas also observed, whereas no toxicity was shown against non-tumor porcine liver cells (N400 μg/mL). The extract was also effective in inhibiting nitric oxide production, as an indicator of the anti-inflammatory potential. The anti-Candida effects varied among different strains of the same species, C. glabrata and C. tropicalis being the most sensible species with an effect directly related with the extract concentrations tested. A significant antibiofilm formation potential was also observed, namely for C. glabrata and C. tropicalis (biofilm reduction N90%). 5-O-Caffeoylquinic and 3-O-caffeoylquinic acids were themost abundant phenolic compounds identified in the extract, and might be related with the observed bioactive effects. Nevertheless, future studies should be carried out to obtain dose-response curves of the isolated active compounds, in order to perform further preclinically testing to quantify the presence of the most active compounds in the extract.
- Phenolic profile obtained by HPLC-DAD-ESI/MS and in vitro bioactivities of Equisetum giganteum L. and Tilia platyphyllos Scop.Publication . Jabeur, Inès; Martins, Natália; Barros, Lillian; Calhelha, Ricardo C.; Vaz, Josiana A.; Achour, Lotfi; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.Medicinal plants are a source of a wide range of bioactive compounds, such as alkaloids, terpenes, steroids and phenolic compounds, which are responsible for multiple biological effects [1, 2]. In the present work, the phenolic composition and bioactive potential of the aqueous and hydroethanolic extracts of Equisetum giganteum L. and Tilia platyphyllos Scop. were evaluated. The phenolic compounds were determined using a Hewlett-Packard 1100 chromatograph, with a diode array detector coupled to a MS detector API 3200 Qtrap through an ESI source and a triple quadrupole-ion trap mass analyser, while the bioactive properties were evaluated in terms of antioxidant, anti-inflammatory, and cytotoxic activities. The hydroethanolic extracts revealed higher amounts of phenolic compounds than infusions, being the concentration of flavonoids (81% of the phenolic composition) remarkably higher than the phenolic acids content (19%), in both species and extracts. T. platyphyllos presented a higher phenolic content (50.4 ± 0.4 mg/g of hydroethanolic extract and 11.65 ± 0.05 mg/g of lyophilized infusion), than E. giganteum (21.7 ± 0.4 mg/g and 4.98 ± 0.03 mg/g, respectively). Moreover, kaempferol- O-glucoside-O-rutinoside was the most abundant flavonoid in E. giganteum extract, while protocatechuic acid and (−)-epicatechin were the most abundant phenolic acid and flavonoid, respectively, in T. platyphyllos extract. Regarding the bioactive assays, both extracts obtained from T. platyphyllos showed the highest potential and none of the extracts showed toxicity in non-tumor liver cells. These biological properties were highly correlated with its content and composition in phenolic compounds. Thus, it would be interesting to evaluate the in vivo efficacy of both plant extracts to unveil the involved modes of action and to establish effective therapeutic doses.
- Maximização da extração de antocianinas de Hibiscus sabdariffa por diferentes métodos para obtenção de corantes alimentaresPublication . Pinela, José; Prieto Lage, Miguel A.; Pereira, Eliana; Lopes, Bernardo; Jabeur, Inès; Barreiro, M.F.; Barros, Lillian; Ferreira, Isabel C.F.R.A consciencialização do consumidor atual sobre a existência de alternativas naturais aos aditivos artificiais, hoje em dia massivamente utilizados na indústria alimentar, mas com potenciais efeitos tóxicos e alergénicos, tem promovido a procura por alimentos formulados com ingredientes de base natural [1,2]. A investigação científica nesta área tem ganho destaque [3,4], mas ainda é necessário alargar o leque de opções disponíveis, encontrar novas fontes e desenvolver processos de extração e estabilização eficientes e sustentáveis. Neste sentido, este estudo foi realizado com o objetivo de maximizar a extração de antocianinas a partir de cálices de H. sabdariffa para obtenção de corantes na gama do vermelho. Os cálices secos e pulverizados foram sujeitos a extrações assistidas por calor e por ultrassons. As variáveis inerentes a cada processo (i.e. tempo, percentagem de etanol e temperatura ou potência) foram combinadas em desenhos fatoriais de 5 níveis e, posteriormente, analisadas pela metodologia de superfície de resposta. Os teores de delfinidina-3-O-sambubiósido e de cianidina-3-O-sambubiósido, determinados por LC-DAD-ESI/MSn, foram utilizados como variáveis dependentes. Os modelos teóricos desenvolvidos foram ajustados com sucesso aos dados experimentais, validados estatisticamente e usados na determinação das condições que maximizam a extração destes pigmentos. O método de extração assistido por ultrassons foi o mais eficiente, originando teores de antocianinas superiores a 50 mg/g de extrato. Posteriormente, determinaram-se os efeitos dose-resposta da razão sólido/líquido nas condições anteriormente otimizadas para as 3 variáveis, tendo-se verificado uma melhoria na capacidade de extração com o aumento deste fator. Os resultados obtidos sustentam o uso de H. sabdariffa como uma fonte sustentável de corantes naturais com aplicações em diferentes setores industriais, sendo uma das fontes mais ricas em antocianinas descritas na literatura.
- Hibiscus sabdariffa L. as a source of nutrients, bioactive compounds and colouring agentsPublication . Jabeur, Inès; Pereira, Eliana; Barros, Lillian; Calhelha, Ricardo C.; Soković, Marina; Oliveira, Beatriz; Ferreira, Isabel C.F.R.The nutritional and bioactive composition of plants have aroused much interest not only among scientists, but also in people's daily lives. Apart from the health benefits, plants are a source of pigments that can be used as natural food colorants. In this work, the nutritional composition of Hibiscus sabdariffa L. was analysed, as well as its bioactive compounds and natural pigments. Glucose (sugar), malic acid (organic acid), a-tocopherol (tocopherol) and linoleic acid (fatty acid) were the major constituents in the corresponding classes. 5-(Hydroxymethyl) furfural was the most abundant non-anthocyanin compound, while delphinidin-3-O-sambubioside was the major anthocyanin both in its hydroethanolic extract and infusion. H. sabdariffa extracts showed antioxidant and antimicrobial activities, highlighting that the hydroethanol extract presents not only lipid peroxidation inhibition capacity, but also bactericidal/fungicidal inhibition ability for all the bacteria and fungi tested. Furthermore, both extracts revealed the absence of toxicity using porcine primary liver cells. The studied plant species was thus not only interesting for nutritional purposes but also for bioactive and colouring applications in food, cosmetic and pharmaceutical industries.
- Caracterização química e bioatividades de Hibiscus sabdariffa L.Publication . Jabeur, Inès; Pereira, Eliana; Barros, Lillian; Calhelha, Ricardo C.; Soković, Marina; Ferreira, Isabel C.F.R.A grande diversidade na composição química das plantas é responsável pelas suas múltiplas aplicações. Para além das propriedades bioativas, as plantas são também fonte de nutrientes e metabolitos secundários nomeadamente, pigmentos naturais que podem ser utilizados em alternativa aos corantes artificiais [1,2]. Neste trabalho, foi determinada a composição de Hibiscus sabdariffa L. em açúcares, ácidos gordos, ácidos orgânicos e tocoferóis, tendo sido também avaliado o potencial bioativo e a composição em fenólicos dos seus extratos aquoso e hidroetanólico. O perfil individual de açúcares foi determinado por HPLC-RI, os ácidos gordos por GC-FID, os ácidos orgânicos por HPLC-DAD e os tocoferóis por HPLC-fluorescência. A análise de compostos fenólicos foi efetuada por HPLC-DAD-ESI/ MS, enquanto que as propriedades bioativas foram avaliadas através de ensaios de atividade antioxidante e antimicrobiana. A hepatotoxicidade dos extratos foi também testada através de uma cultura primária de células de fígado de porco. A glucose (açúcar), o ácido málico (ácido orgânico), o α- tocoferol (tocoferol) e o ácido linoleico (ácido gordo) foram os principais constituintes nas classes correspondentes. 5-(Hidroximetil)furfural foi o composto não-antociânico mais abundante, enquanto delfinidina-3-O-sambobiósido foi a antocianina presente em maior concentração em ambos os extratos testados. Apesar de ambos os extratos de H. sabdariffa terem demonstrado atividade antioxidante e antimicrobiana, destaca-se o extrato hidroetanólico com uma maior capacidade de inibição da peroxidação lipídica em homogeneizados de células cerebrais de porco e maiores efeitos bactericidas e fungicidas. Foi também evidente que nenhum dos extratos analisados revelou hepatotoxicidade. Deste modo, a espécie H. sabdariffa revelou ser interessante não só como fonte de nutrientes, mas também de compostos bioativas e pigmentos, com enorme interesse para as indústrias alimentar, cosmética e farmacêutica.
- The broad spectrum of bioactive properties of phenolic extracts: a prospective study in three different plantsPublication . Jabeur, Inès; Ferreira, Isabel C.F.R.; Abreu, Rui M.V.; Achour, LotfiNatural resources like plants are currently used all over developed and under developed countries of the world as traditional home remedies and are promising agents for drug discovery as they play crucial role in traditional medicine. The use of plants for medicinal purpose usually varies from country to country and region to region because their use depends on the history, culture, philosophy and personal attitudes of the users (Ahmad et al., 2015). The use of plants and plant products as drugs predates the written human history (Hayta et al., 2014). Plants are a very important resource for traditional drugs and around 80% of the population of the planet use plants for the treatment of many diseases and traditional herbal medicine accounts for 30-50% of the total medicinal consumption in China. In North America, Europe and other well-developed regions over 50% of the population have used traditional preparations at least once (Dos Santos Reinaldo et al., 2015). Medicinal plants have been used over years for multiple purposes, and have increasingly attract the interest of researchers in order to evaluate their contribution to health maintenance and disease’s prevention (Murray, 2004). Recently between 50,000 and 70,000 species of plants are known and are being used in the development of modern drugs. Plants were the main therapeutic agents used by humans from the 19th century, and their role in medicine is always topical (Hayta et al., 2014). The studies of medicinal plants are rapidly increasing due to the search for new active molecules, and to improve the production of plants or bioactive molecules for the pharmaceutical industries (Rates, 2001). Several studies have been reported, but numerous active compounds directly responsible for the observed bioactive properties remain unknown, while in other cases the mechanism of action is not fully understood. According to the WHO 25% of all modern medicines including both western and traditional medicine have been extracted from plants, while 75% of new drugs against infective diseases that have arrived between 1981 and 2002 originated from natural sources, it was reported that the world market for herbal medicines stood at over US $60 billion per year and is growing steadily (Bedoya et al., 2009). Traditional medicine has an important economic impact in the 21st century as it is used worldwide, taking advantage on the low cost, accessibility, flexibility and diversity of medicinal plants (Balunas & Kinghorn, 2005).
- Exploring the chemical and bioactive properties of: Hibiscus sabdariffa L. calyces from Guinea-Bissau (West Africa)Publication . Jabeur, Inès; Pereira, Eliana; Caleja, Cristina; Calhelha, Ricardo C.; Soković, Marina; Catarino, Luís; Barros, Lillian; Ferreira, Isabel C.F.R.Different external factors influence the chemical characteristics of natural products, varying according to the geographic origin. The present study determined the nutritional and chemical composition of Hibiscus sabdariffa L. dried calyces (Guinea-Bissauan origin), as well as the phenolic composition, antioxidant, anti-inflammatory, cytotoxicity and antimicrobial activity of its infusion and hydroethanolic extracts. Among the chemical composition, glucose and quinic acid showed the major concentration for sugars and organic acids, respectively. Palmitic acid and α-tocopherol were the most abundant lipophilic compounds. The individual phenolic compounds were analysed through HPLC-DAD-ESI/MS. Thirteen compounds were identified in the hydroethanolic extract, while twelve were identified in the infusion, being 3- O-caffeoylquinic acid the major non-anthocyanin compound. Three anthocyanins were identified, being delphinidin-3-O-sambubioside the most abundant. Both extracts showed promising results in all the bioactive assays. This study exhibited beneficial properties of H. sabdariffa and also emphasized the potential applications of this plant in different industrial sectors.
- Hibiscus sabdariffa L. como uma fonte de nutrientes, compostos bioativos e agentes corantesPublication . Jabeur, Inès; Pereira, Eliana; Barros, Lillian; Soković, Marina; Ferreira, Isabel C.F.R.As plantas são uma fonte de pigmentos naturais que podem ser utilizados como corantes alimentares com baixo risco de toxicidade e com benefícios nutricionais e bioativos. Esta temática despertou o interesse da comunidade científica e desencadeou estudos com o objetivo de explorar matrizes naturais como fonte de compostos bioativos e corantes. Neste trabalho, a composição química de Hibiscus sabdariffa L. em compostos hidrofílicos (açúcares e ácidos orgânicos) e lipofílicos (ácidos gordos e tocoferóis) foi determinada por técnicas cromatográficas. Além disso, foram avaliadas as propriedades bioativas (antioxidante e antimicrobiana) e o perfil fenólico dos seus extratos aquoso e hidroetanólico. A frutose e a glucose foram os açúcares livres detetados, estando este último presente em maior quantidade (6,5±0,6 g/100 g massa seca). Foram identificados quatro ácidos orgânicos, ácido oxálico, málico, shiquímico e fumárico, destacando o ácido málico que foi encontrado em maior concentração (9,10±0,09 g/100 g). Quanto aos tocoferóis foram identificados os vitâmeros α e β-tocoferóis, sendo o α-tocoferol o mais abundante (39,19±0,06 mg/100 g). Na determinação do perfil de ácidos gordos, foram identificados 18 compostos, evidenciando-se o ácido linoleico com uma contribuição de 32,65±0,07%. Na avaliação do potencial antioxidante e antimicrobiano, ambos os extratos apresentaram atividade. Analisando o perfil fenólico, foram identificados 12 compostos, sendo o 5- (hidroximetil)furfural e a delfinidina-3-O-sambobiósido as moléculas não-antociânica e antociânica mais abundante, respetivamente. Tendo em conta os resultados obtidos, esta espécie revelou ser uma fonte promissora de compostos bioativos e corantes, que poderá ser explorada pelas indústrias alimentar, cosmética e farmacêutica.