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- 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.
- 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).
- 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.
- Contribution of the phenolic composition to the antioxidant, anti-inflammatory and antitumor potential 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.Naturally-occurring phytochemicals have received pivotal attention in the last few years, due to the increasing evidence of biological activities. Thus, in the present study, the antioxidant, anti-inflammatory and antitumor potentials of hydroethanolic extracts rich in phenolic compounds obtained from Equisetum giganteum L. and Tilia platyphyllos Scop. were assessed and directly correlated with their content of phenolic compounds, by using HPLC-DAD-ESI/MS analysis. T. platyphyllos showed the higher bioactive potential, evaluated in terms of antioxidant (radical scavenging effects-105 µg mL -1 , reducing power-123 µg mL -1 , ß-carotene bleaching inhibition-167 µg mL -1 , and lipid peroxidation inhibition-56 µg mL -1 ), anti-inflammatory (225 µg mL -1 inhibited 50% of nitric oxide production) and antitumor (breast-224 µg mL -1 ; lung-247 µg mL -1 ; cervical-195 µg mL -1 and hepatocellular-173 µg mL -1 carcinoma cells) activity, without having cytotoxic effects ( > 400 µg mL -1 ). These biological properties were positively correlated with its content and composition of phenolic compounds. Flavonoid contents were markedly higher than the content of phenolic acids, in both samples, being respectively 50.4 mg g -1 and 11.65 mg g -1 for T. platyphyllos, and 21.7 mg g -1 and 4.98 mg g -1 for E. giganteum. Moreover, while in E. giganteum extract, kaempferol-O-glucoside-O-rutinoside was the most abundant flavonoid, in T. platyphyllos extract protocatechuic acid and (-)-epicatechin were the most abundant phenolic acid and flavonoid, respectively. In relation to their content of phenolic acids, protocatechuic and caffeic acids existed in higher abundance in T. platyphyllos and E. giganteum hydroethanolic extracts, respectively. However, 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.
- Optimization and comparison of maceration and ultrassound assisted extraction systems for the production of a colorant extract from Hibiscus sabdariffa L. flowersPublication . Jabeur, Inès; Pereira, Eliana; Prieto Lage, Miguel A.; Antonio, Amilcar L.; Barros, Lillian; Ferreira, Isabel C.F.R.Hibiscus sabdariffa L. is an herbaceous medicinal plantused as infusion for the treatment of several disorders, namely, fever and high blood pressure, gastrointestinal and hepatic diseases. In addition to those health benefits, the calyces area potential source of natural pigments, due to its high content in anthocyanins. This work aimed to optimize the experimental conditions of anthocyanins’extraction from dried calyces of H. sabdariffa, comparing two methodologies, maceration and ultrasound assisted extraction, in order to develop a natural colorant. To obtain the conditions that maximize anthocyanins’ extraction, a response surface methodology (RSM) was applied using the circumscribed central composite design of three variables with five levels. Time, temperature and ethanol - water proportion - in the case of maceration, were the relevant independent variables, while for ultrasound assisted extraction, the ultrasonic power was used instead of temperature which was kept constant. Two anthocyanin compounds were identified by HPLC-DAD-ESI/MS: delphinidin3-sambubioside and cyanidin-3-sambubioside. The responses used as criteria were the quantification of the identified anthocyanins and the extraction yield of the final residue. Ultrasound assisted extraction proved to be the most effective method: 43 min, 390 W and 46 % of ethanol. At these optimal conditions, the extraction yield was 61.2%, with a total anthocyanins’ content of 23.1 mg/g dried plant, and 47.5 mg/g extract. Additionally, the response values were slightly improved by studying the solid/liquid ratio effect using the optimal conditions in dose-response format (5 to 200 g/L), showing continuously decreasing values as the solid/liquid ratio increases. Overall, the obtained results showed the possibility of using H. sabdariffa flowers as a source of anthocyanin compounds for industrial applications.
- 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.Este estudo teve como objetivo maximizar a extração de antocianinas a partir de cálices de Hibiscus sabdariffa L. utilizando métodos assistidos por calor (EAC) e ultrassom (EAU), para obtenção de um corante natural na gama do vermelho. 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 (MSR). O teor de antocianinas foi usado como variável dependente. Os modelos teóricos desenvolvidos foram validados estatisticamente e usados na determinação das condições que maximizam a extração destes pigmentos. O método EAU foi o mais eficiente, tendo originado teores de antocianinas superiores a 50 mg/g de extrato. Os efeitos dose-resposta da razão sólido/líquido foram seguidamente determinados nas condições otimizadas para as 3 variáveis, tendo-se verificado uma melhoria na capacidade de extração com o aumento deste fator. Os resultados sustentam o uso de H. sabdariffa como uma fonte sustentável de corantes naturais.
- 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.
- 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.
- Hibiscus sabdariffa L. calyces as a source of anthocyanins rich extracts to be used as a natural food colouring agentePublication . Jabeur, Inès; Pereira, Eliana; Reis, Filipa S.; Prieto Lage, Miguel A.; Barros, Lillian; Ferreira, Isabel C.F.R.Colour is the most important sensory perception when it comes to setting peoples expectations regarding the likely taste and flavour of food [l]. Since the consumers are more aware regarding the additives that are incorporated into food products, they have shown a preference for the consumption of natural additives over the artificial ones. This hás been one ofthe research lines ofthe scientific community, searching for natural additives to replace the artificial counterparts [2]. The present work studies the stability of an extract obtained from hibiscus calyces (Hibiscus sabdariffa L.), to test its possible use as a natural colourant in foods. The aqueous stability of the extract was monitored using the total anthocyanins content (TAC) as response (determined by HPLC-DAD) in function of time (t, 14 days), temperature (T, 4 to 70 °C), and pH (2 to 6). Aided by mechanistic/phenomenological models, the conditions favouring the stabilization ofthe extract were provided. The results obtained showed that the aqueous stability of the H. sabdariffa extracts was higher at lower pH values, shorter t values and T between 4 to 35 °C. However, certain new stable combinations of conditions were found, providing a wide range of conditions, in which the TAC ofH. sabdariffa extracts will remain stable at values of T within the range of50 to 70°C. Such facts, will help to understand how to incorporate stable natural extracts, rich in TAC, as natural colorant additives in food products, that may require strong processing conditions, such as bakery and dairy products. These results provide useful information for: i) potential industrial use offí. sabdariffa extract as alternative sources of natural additives rich in TAC; and ii) shelf-life calculations and TAC loss predictions at specific conditions of T and pH. Finally, the results obtained showed a certain agreement with previous reports regarding the stability of anthocyanin compounds, but providing a new alternative source.