Browsing by Author "Andrade, Paula B."
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- Development and evaluation of an HPLC-DAD method for the phenolic compounds from olive fruitsPublication . Ferreira da Vinha, Ana; Silva, Branca M.; Andrade, Paula B.; Seabra, Rosa M.; Pereira, José A.; Oliveira, M. Beatriz P.P.A new HPLC=DAD methodology for separating nine phenolic compounds is described. This methodology is applied to the definition of qualitative and quantitative profiles of three Portuguese olive fruit cultivars (Cobranc¸osa, Madural and Verdeal). Two different extraction methods were needed for the complete definition of their profiles, one of them including a Sep-pack C18 cleaning step.The chromatographic separation was achieved using a Spherisorb ODS2 (25.060.46 cm; 5 mm, particle size) column.The solvent system used was a gradient of water-formic acid (19:1) and methanol, with a flow rate of 0.9 mL=min. The detection limit values for phenolic compounds were between 0.04 and 4.32 mg=mL and the method was precise. As ageneral rule, the recovery values were high. This technique can also be useful in the discrimination of Portuguese olive fruit cultivars.
- Development of an HPLC/DAD method for determination of phenolic profile in portuguese olive fruitsPublication . Ferreira da Vinha, Ana; Andrade, Paula B.; Silva, Branca M.; Pereira, José A.; Valentão, Patrícia; Seabra, Rosa M.; Oliveira, M. BeatrizPolyphenolic compounds inliuence the sensorial properties of olive fruits and virgin olive oils and are imporlant markers for studying fruit characteristics of different cultivars and for controlling oil production processes . A few chromatographic methods have been used to study the phenolic compounds of olive fruit . This communication reports the development of a new HPLCIDAD methodology to separate, identify aml quanlily lhe phenolic compounds from Portuguese olive fruit cultivars (Cobrançosa, Madura/and Verdeal).
- Dracaena draco L. fruit: phytochemical and antioxidant activity assessmentPublication . Silva, Branca M.; Santos, Rui P.; Mendes, Lídia S.; Guedes de Pinho, Paula; Valentão, Patrícia; Andrade, Paula B.; Pereira, José A.; Carvalho, MárciaThe present study reports for the first time the metabolite profile and antioxidant activity of aqueous extract obtained from Dracaena draco L. fruit. Volatiles profile was determined by HS-SPME/GC-IT-MS, with 9 compounds being identified, distributed by several distinct chemical classes: 1 alcohol, 3 aldehydes, 2 carotenoid derivatives, and 3 terpenic compounds. Aldehydes constituted the most abundant class in this exotic berry, representing 59% of total identified volatile compounds. Phenolics profile was determined by HPLC/DAD and 5 constituents were identified: 5-O-caffeoylquinic, 3,5-O-dicaffeoylquinic, ferulic and sinapic acids, and quercetin-3-O-rutinoside. The major phenolic compound is quercetin-3-O-rutinoside, comprising 42% of the total phenolic content. Organic acids composition was also characterized, by HPLC-UV, and oxalic, citric, l-ascorbic, malic, quinic and shikimic acids were determined. The most abundant is quinic acid, representing 39% of the total organic acid content. The antioxidant potential of this matrix was assessed by (i) reducing power of Fe3+/ferricyanide complex, (ii) scavenging effect on DPPH free radicals, and (iii) ability to inhibit the 2,2´-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis in human erythrocytes. Strawberry (Fragaria × ananassa Duch. cv. Camarosa) extract was used for comparison purposes. All assay models showed remarkable concentration dependent antioxidant activity, reducing power and radical scavenging efficiency for D. draco fruit, being invariably higher than that of strawberry extract. This is the first report showing that D. draco fruit is a promising new antioxidant agent.
- Evaluation of free radical-scavenging and antihemolytic activities of quince (Cydonia oblonga) leaf: a comparative study with green tea (Camellia sinensis)Publication . Costa, Rossana M.; Magalhães, Ana S.; Pereira, José A.; Andrade, Paula B.; Valentão, Patrícia; Carvalho, Márcia; Silva, Branca M.This study aimed to determine the phenolic profile and to investigate the antioxidant potential of quince (Cydonia oblonga) leaf, comparing it with green tea (Camellia sinensis). For these purposes, methanolic extracts were prepared and phenolics content of quince leaf was determined by HPLC/UV. The antioxidant properties were assessed by Folin-Ciocalteu reducing capacity assay and by the ability to quench the stable free radical 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and to inhibit the 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis of human erythrocytes.5-O-Caffeoylquinic acid was found to be the major phenolic compound in quince leaf extract. Quince leaf exhibited a significantly higher reducing power than green tea (mean value of 227.8 +/- 34.9 and 112.5 +/- 1.5 g/kg dry leaf, respectively). Quince leaf extracts showed similar DPPH radical-scavenging activities (EC50 mean value of 21.6 +/- 3.5 microg/ml) but significantly lower than that presented by green tea extract (EC50 mean value of 12.7 +/- 0.1 microg/ml). Under the oxidative action of AAPH, quince leaf methanolic extract significantly protected the erythrocyte membrane from hemolysis in a similar manner to that found for green tea (IC50 mean value of 30.7 +/- 6.7 and 24.3 +/- 9.6 microg/ml, respectively, P > 0.05). These results point that quince leaf may have application as preventive or therapeutic agent in diseases in which free radicals are involved.
- First report on Cydonia oblonga Miller anticancer potential: differential antiproliferative effect against human kidney and colon cancer cellsPublication . Carvalho, Márcia; Silva, Branca M.; Silva, Renata; Valentão, Patrícia; Andrade, Paula B.; Bastos, Maria L.The present study reports the phenolic profile and antiproliferative properties of quince (Cydonia oblonga Miller) leaf and fruit (pulp, peel, and seed) against human kidney and colon cancer cells. The phenolic profiles of quince methanolic extracts were determined by high-performance liquid chromatography (HPLC)/diode array detector (DAD). 5-O-Caffeoylquinic acid was always one of the two major phenolic compounds present in all extracts, except for seed. Our results revealed that quince leaf and fruit extracts exhibited distinctive antiproliferative activities. The extracts from quince leaf showed concentration-dependent growth inhibitory activity toward human colon cancer cells (IC(50) = 239.7 +/- 43.2 microg/mL), while no effect was observed in renal adenocarcinoma cells. Concerning the fruit, seed extracts exhibited no effect on colon cancer cell growth, whereas strong antiproliferative efficiency against renal cancer cells was observed for the highest concentration assayed (500 microg/mL). The antiproliferative activity of pulp and peel extracts was low or absent in the selected range of extract concentrations. This is the first report showing that C. oblonga may be useful as a cancer chemopreventive and/or chemotherapeutic agent.
- Green tea: a promising anticancer agent for renal cell carcinomaPublication . Carvalho, Márcia; Jerónimo, Carmen; Valentão, Patrícia; Andrade, Paula B.; Silva, Branca M.Renal cell carcinoma (RCC) is one of the most lethal amongst the urologic malignancies, comprising three percent of all human neoplasms, and its incidence appears to be rising. RCC is refractory to both chemotherapy and radiotherapy. Therefore, the discovery of new strategies for therapeutic intervention remains a priority. Green tea (Camellia sinensis) and tea polyphenols have been proposed to exert protective effects against several types of cancer, based on preclinical and clinical trial data; however, the anticarcinogenic activity of green tea towards RCC is unknown. In this study, a targeted metabolite analysis on a green tea leaves methanolic extract was performed by HPLC/DAD and the antiproliferative activity of the extract was assayed using human renal cancer cell lines A-498 and 769-P. The total phenolic content was very high (31.8% of methanolic extract), and the main compounds were flavan-3-ols (94.3% of the total phenolic content), and especially (−)-epigallocatechin-3-gallate (35.9% of the total phenolic content). In addition, two methylxanthines – theophylline and caffeine – were also present in the extract, caffeine being the most abundant. Green tea extract strongly inhibited the growth of both RCC cell lines in a concentration-dependent manner, with IC50 values of 54 ± 10 and 129 ± 28 μg/ml for A-498 and 769-P cells, respectively. This is the first report showing that green tea is likely to be an effective anticancer agent for renal cell carcinoma.
- Hypericum androsaemum infusion increases tert-butyl hydroperoxide-induced mice hepatotoxicity in vivoPublication . Valentão, Patrícia; Carvalho, Márcia; Carvalho, Félix; Fernandes, Eduarda; Pires das Neves, Ricardo; Pereira, M. Lourdes; Andrade, Paula B.; Seabra, Rosa M.; Bastos, M. LourdesIncreasing evidence regarding free radical generating agents indicates that the sustained production of high levels of reactive oxygen species (ROS) can cause hepatotoxicity. Being a short chain analog of lipid peroxide, tert-butyl hydroperoxide (t-BHP) is metabolized into free radical intermediates by cytochrome P450 in hepatocytes, which initiate lipid peroxidation, glutathione depletion and cell damage. The aim of the present study was to evaluate the putative protective effect of Hypericum androsaemum lyophilised infusion against t-BHP-induced mice hepatotoxicity in vivo, which has already been shown to be antioxidant in vitro. However, the results showed that the oral pretreatment with Hypericum androsaemum infusion (4, 20 and 100 mg/kg) for 4 days before a single intraperitoneal dose of t-BHP (1.8 mmol/kg) potentiated the t-BHP-induced hepatotoxicity. In fact, it was observed a potentiation in the depletion of total glutathione and reduced glutathione (GSH) contents and increase in oxidised glutathione (GSSG) level. Also the histopathological evaluation of the mice livers revealed that the infusion raised the incidence of liver lesions induced by t-BHP. These data do not corroborate any effect of Hypericum androsaemum infusion as hepatoprotector, but rather as a potentiator of hepatotoxicity in the present experimental conditions.
- Phenolic compounds in three portuguese olive fruits varietiesPublication . Ferreira da Vinha, Ana; Andrade, Paula B.; Silva, Branca M.; Pereira, José A.; Valentão, Patrícia; Seabra, Rosa M.; Oliveira, M. BeatrizThis book looks at the biosynthesis and significance of phytochemicals, their analysis and antioxidant behaviour, paying special attention to their anti-oxidant properties.
- Phenolic profiles of portuguese olive fruits (Olea europaea L.): influences of cultivar and geographical originPublication . Ferreira da Vinha, Ana; Ferreres, Federico; Silva, Branca M.; Valentão, Patrícia; Gonçalves, Ana; Pereira, José; Oliveira, M. Beatriz P.P.; Seabra, Rosa M.; Andrade, Paula B.The phenolic compounds present in 29 samples of olive fruits were analysed by reversed-phase HPLC/DAD and/or HPLC-DAD/ ESI-MS/MS. All samples were collected during the normal picking period for olive oil production, in north and central Portugal, and were obtained from 18 different olive cultivars. Two different extraction methods were necessary for the complete quantification of phenolic compounds, a methanolic extraction and an extraction which included a solid-phase extraction (SPE) cleaning step. The analyses showed that all samples presented a similar profile, which included at least six identified phenolic compounds: hydroxytyrosol, luteolin 7-O-glucoside, oleuropein, rutin, apigenin 7-O-glucoside and luteolin. Several samples also contained 5-O- caffeoylquinic acid, verbascoside, quercetin 3-O-rhamnoside, cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside. In all samples, hydroxytyrosol and oleuropein were the major compounds identified while, in general, rutin and luteolin 7-O- glucoside were the two main flavonoids. The influences of maturation index, nature of the cultivar and geographical origin are discussed.
- Phytochemical profiles and inhibitory effect on free radical-induced human erythrocyte damage of Dracaena draco leaf: a potential novel antioxidant agentPublication . Santos, Rui P.; Mendes, Lídia S.; Silva, Branca M.; Guedes de Pinho, Paula; Valentão, Patrícia; Andrade, Paula B.; Pereira, José A.; Carvalho, MárciaThe present study reports for the first time the metabolite profile and antioxidant activity of aqueous extract obtained from Dracaena draco L. leaf. Volatiles profile was determined by HS-SPME/GC-IT-MS, with 34 compounds being identified, distributed by distinct chemical classes: 2 alcohols, 5 aldehydes, 16 carotenoid derivatives and 8 terpenic compounds. Carotenoid derivative compounds constituted the most abundant class in leaf (representing 45% of total identified compounds). Phenolics profile was determined by HPLC/DAD and 9 constituents were identified: 2 hydroxycinnamic acid derivatives – 5-O-caffeoylquinic and 3,5-O-dicaffeoylquinic acids; 4 hydroxycinnamic acids – caffeic, p-coumaric, ferulic and sinapic acids and 3 flavonol glycosides – quercetin-3-O-rutinoside, kaempferol-3-O-glucoside and kaempferol-3-O-rutinoside. The most abundant phenolic compound is quercetin-3-O-rutinoside (representing 50.2% of total polyphenols). Organic acids composition was also characterised, by HPLC–UV and oxalic, citric, malic and fumaric acids were determined. Oxalic and citric acids were present in higher amounts (representing 47%, each). The antioxidant potential of this material was assessed by the ability to protect against free radical-induced biomembrane damage, using human erythrocyte as in vitro model. Leaf extract strongly protected the erythrocyte membrane from haemolysis (IC50 of 39 ± 11 μg/ml), in a time- and concentration-dependent manner. This is the first report showing that D. draco leaf is a promising antioxidant agent.