Browsing by Author "Seabra, Rosa M."
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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).
- 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.