Percorrer por autor "Sousa, Carla"
A mostrar 1 - 10 de 23
Resultados por página
Opções de ordenação
- Antioxidative properties of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves against DPPH, superoxide radical, hydroxyl radical and hypochlorous acidPublication . Vrchovska, Vendula; Sousa, Carla; Valentão, Patrícia; Ferreres, Frederico; Pereira, J.A.; Seabra, Rosa M.; Andrade, Paula B.The ability of the aqueous extract of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves to act as a scavenger of DPPH- and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid) was investigated. A phytochemical study was also undertaken, and thirteen phenolic compounds and five organic acids were identified and quantified. Tronchuda cabbage extracts exhibited antioxidant capacity in a concentration-dependent manner in all assays, although some pro-oxidant effect was also noticed. The samples with higher phenolic and organic acid contents displayed the major antioxidant potentials.
- Brassica oleracea var. costata: comparative study on organic acids and biomass production with other cabbage varietiesPublication . Sousa, Carla; Pereira, David M.; Taveira, Marcos; Dopico-García, Sonia; Valentão, Patrícia; Pereira, J.A.; Bento, Albino; Andrade, Paula B.BACKGROUND: A study was undertaken to evaluate the effect of agronomic practices, harvesting time and leaf age on the organic acid composition and biomass production of Brassica oleracea L. var. costata DC (tronchuda cabbage). Samples were cultivated under eight different fertilisation regimes (two levels each of nitrogen, boron and sulfur, an organic fertiliser and no fertiliser) and collected at three different times. RESULTS: Principal component analysis of the data indicated significant differences. Three principal components with an eigenvalue higher than one accounted for 79.0% of the total variance of the data set. Samples obtained with conventional fertilisation were characterised by the highest values of fresh weight. External leaves showed higher total organic acid and malic acid contents than internal leaves,while the latterwere characterised by higher proportions of citric acid. For consecutive harvests, total organic acid concentration decreased in both external and internal leaves. CONCLUSION: The use of a conventional fertilisation regime (nitrogen, boron or sulfur) improved the growth of B. oleracea var. costata without affecting its organic acid profile. However, for consecutive harvests, total organic acid concentration was observed to decrease independently of the agronomic practices tested. Leaf age influenced the quantitative composition of organic acids.
- Chemical and antioxidative assessment of dietary turnip (Brassica rapa var. rapa L.)Publication . Fernandes, Fátima; Valentão, Patrícia; Sousa, Carla; Pereira, J.A.; Seabra, Rosa M.; Andrade, Paula B.The phenolic compounds and organic acids of turnip (Brassica rapa var. rapa L.) edible parts (leaves and stems, flower buds and roots) were determined by HPLC–DAD and HPLC–UV, respectively. The results revealed a profile composed of 14 phenolics (3-p-coumaroylquinic, caffeic, ferulic and sinapic acids, kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-sophoroside-7-O-sophoroside, kaempferol 3-O-(feruloyl/caffeoyl)-sophoroside-7-O-glucoside, kaempferol 3,7-O-diglucoside, isorhamnetin 3,7-O-diglucoside, kaempferol 3-O-sophoroside, 1,2-disinapoylgentiobiose, 1,20-disinapoyl-2-feruloylgentiobiose, kaempferol 3-O-glucoside and isorhamnetin 3-O-glucoside) and six organic acids (aconitic, citric, ketoglutaric, malic, shikimic and fumaric acids). The quantification of the identified compounds showed kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-(feruloyl/caffeoyl)-sophoroside-7-O-glucoside, isorhamnetin 3,7-O-diglucoside and isorhamnetin 3-O-glucoside as the main phenolics, and malic acid as the organic acid present in highest amounts. A screening of the antioxidative potential was also performed by means of the DPPH radical scavenging assay. Turnip flower buds exhibited the strongest antioxidant capacity.
- Chemical composition and antioxidant activity of tronchuda cabbage internal leavesPublication . Ferreres, Frederico; Sousa, Carla; Vrchovska, Vendula; Valentão, Patrícia; Pereira, J.A.; Seabra, Rosa M.; Andrade, Paula B.A phytochemical study was undertaken on the internal leaves of tronchuda cabbage (Brassica oleracea L. var. costata DC). Seventeen phenolic compounds were characterized and quantified by reversed-phase HPLCDAD-ESI-MSn and HPLC/DAD, respectively: quercetin 3-O-sophoroside-7-O-glucoside, 3-p-coumaroylquinic acid, kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-(caffeoyl)-sophoroside-7-O-glucoside, sinapoyl glucoside acid, kaempferol 3-O-(sinapoyl)-sophoroside-7-Oglucoside, kaempferol 3-O-(feruloyl)-sophoroside-7-Oglucoside, kaempferol 3-O-(p-coumaroyl)-sophoroside- 7-O-glucoside, 4-p-coumaroylquinic acid, sinapic acid, kaempferol 3-O-sophoroside, 3 isomeric forms of 1,2- disinapoylgentiobiose, 1-sinapoyl-2-feruloylgentiobiose, 1,2,2-trisinapoylgentiobiose and 1,2'-disinapoyl-2-feruloylgentiobiose. Seven organic acids (aconitic, citric, ascorbic, malic, quinic, shikimic and fumaric acids) were also identified and quantified. The hot water extract of tronchuda cabbage internal leaves was investigated for its capacity to act as a scavenger of DPPH- radical and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid), exhibiting antioxidant capacity in a concentration dependent manner against all radicals.
- Composição química e actividade antioxidante das folhas internas da couve tronchudaPublication . Pereira, J.A.; Sousa, Carla; Ferreres, Frederico; Valentão, Patrícia; Seabra, Rosa M.; Andrade, Paula B.A couve tronchuda (Brassica oleracea L. var. costata DC) é uma das couves mais consumidas pelos portugueses, especialmente durante o Inverno, apresentando as folhas (internas e externas) diferenças organolépticas marcadas. No presente trabalho procedeu-se à caracterização química das folhas internas de couve tronchuda, através da identificação e quantificação dos compostos fenólicos e dos ácidos orgânicos que as compõem e avaliou-se o seu potencial antioxidante. Foram identificados e quantificados, por HPLC-DAD-ESI-MS e HPLC/DAD, respectivamente, 17 compostos fenólicos: quercetina 3-O-soforósido-7-O-glucósido, ácido 3-p-cumaroilquínico, campferol 3-O-soforósido-7-O-glucósido, campferol 3-O-(cafeoil)-soforósido-7-O-glucósido, ácido sinapoilglucósido, campferol 3-O-(sinapoil)-soforósido-7-O-glucósido, campferol 3-O-(feruloil)-soforósido-7-O-glucósido, campferol 3-O-(p-cumaroil)-soforósido-7-O-glucósido, ácido 4-p-cumaroilquínico, ácido sinápico, campferol 3-O-soforósido, 3 isómeros de 1,2-di-sinapoilgentiobiose, 1-sinapoil-2-feruloilgentiobiose, 1,2,2-tri-sinapoilgentiobiose e 1,2’-di-sinapoil-2-feruloilgentiobiose. Foram também identificados e quantificados, por HPLC/UV, sete ácidos orgânicos (ácidos aconítico, cítrico, ascórbico, málico, quínico, chiquímico e fumárico). A actividade antioxidante do extracto aquoso foi aferida pela capacidade para interceptar o radical DPPH e espécies reactivas de oxigénio (radicais superóxido e hidroxilo e ácido hipocloroso), tendo revelado grande efeito protector.
- Free amino acids of Tronchuda Cabbage (Brassica oleracea L. Var. costata DC): influence of leaf position (internal or external) and collection timePublication . Oliveira, Andreia P.; Pereira, David M.; Andrade, Paula B.; Valentão, Patrícia; Sousa, Carla; Pereira, J.A.; Bento, Albino; Rodrigues, M.A.; Seabra, Rosa M.; Silva, Branca M.The free amino acid profile of 18 samples of tronchuda cabbage (Brassica oleracea L. var. costata DC) leaves, harvested at three different months, was determined by HPLC/UV−vis. The tronchuda cabbage leaves total free amino acid content varied from 3.3 to 14.4 g/kg fresh weight. Generally, arginine was the major compound, followed by proline, threonine, glutamine, cysteine, and glutamic acid. This study indicates that free amino acids are not similarly distributed: in external leaves, proline and arginine were the major free amino acids, while in internal ones, arginine was the main free amino acid, followed by threonine, glutamine, and cysteine. Significant differences were observed for valine, proline, arginine, leucine, cysteine, lysine, histidine, and tyrosine contents. The levels of some free amino acids were significantly affected by the collection period. In external leaves, this occurred with glutamic acid, serine, valine, leucine, cysteine, and ornithine contents, while in internal leaves, it occurred with aspartic acid, arginine, and total contents.
- In vitro cultures of Brassica oleracea L. var. costata DC: potential plant bioreactor for antioxidant phenolic compoundsPublication . Taveira, Marcos; Pereira, David M.; Sousa, Carla; Ferreres, Frederico; Andrade, Paula B.; Martins, Anabela; Pereira, J.A.; Valentão, PatríciaIn this work were studied the phenolic composition of in vitro material (shoots, calli, and roots) of Brassica oleracea var. costata and its antioxidant capacity. Samples were obtained in different culture medium, with distinct supplementations to verify their influence on those parameters. Phenolic determination was achieved by HPLC-DAD. Antioxidant activity was assessed against DPPH•. In calli and roots no phenolic compound was identified. In shoots was verified the presence of 36 compounds, which included hydroxycinnamic acids, flavonoids (kaempferol and quercetin derivatives), and hydroxycinnamic acyl glycosides (with a predominance of synapoyl gentiobiosides). MS liquid medium supplemented with 2 mg/L benzylaminopurine (BAP) and 0.1 mg/L naphthaleneacetic acid (NAA) revealed to be the best in vitro condition to produce shoot material with highest phenolic compound contents and stronger antioxidant potential, thus with a possible increase of health benefits.
- In vitro cultures of Brassica oleracea L. Var. Costata DC: potential plant bioreactor for antioxidant phenolic compoundsPublication . Taveira, Marcos; Pereira, David M.; Andrade, Paula B.; Sousa, Carla; Ferreres, Frederico; Martins, Anabela; Pereira, J.A.; Seabra, Rosa M.; Valentão, Patrícia
- Inflorescences of Brassicacea species as source of bioactive compounds: a comparative studyPublication . Sousa, Carla; Taveira, Marcos; Valentão, Patrícia; Fernandes, Fátima; Pereira, J.A.; Estevinho, Leticia M.; Bento, Albino; Ferreres, Frederico; Seabra, Rosa M.; Andrade, Paula B.Two Brassica oleracea varieties (B. oleracea L. var. costata DC and B. oleracea L. var. acephala) and Brassica rapa L. var. rapa inflorescences were studied for their chemical composition and antioxidant capacity. Phenolic compounds and organic acids profiles were determined by HPLC–DAD and HPLC–UV, respectively. B. oleracea var. costata and B. oleracea L. var. acephala inflorescences presented a similar qualitative phenolic composition, exhibiting several complex kaempferol derivatives and 3-p-coumaroylquinic acid, while B. rapa var. rapa was characterized by kaempferol and isorhamnetin glycosides and several phenolic acids derivatives. B. oleracea L. var. costata and B. rapa var. rapa showed the highest phenolics content. The three Brassica exhibited the same six organic acids (aconitic, citric, pyruvic, malic, shikimic and fumaric acids), but B. oleracea L. var. acephala presented a considerably higher amount. Each inflorescence was investigated for its capacity to act as a scavenger of DPPH radical and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid), exhibiting antioxidant capacity in a concentration dependent manner against all radicals. These samples were also studied for its antimicrobial potential against Gram-positive and Gram-negative bacteria and fungi, displaying antimicrobial capacity only against Gram-positive bacteria.
- Influence of different fertilization regimes on the amounts of organic acids of Brassica oleracea L. var. costata DC.Publication . Ribeiro, Bárbara; Sousa, Carla; Lopes, Graciliana; Pereira, David M.; Taveira, Marcos; Dopico-García, Sonia; Pereira, J.A.; Bento, Albino; Rodrigues, M.A.; Valentão, Patrícia; Seabra, Rosa M.; Andrade, Paula B.
- «
- 1 (current)
- 2
- 3
- »