Percorrer por autor "Taveira, Marcos"
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- 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.
- Evolution of Brassica rapa L. var. rapa volatile composition by HS-SPME and GC/IT-MS.Publication . Taveira, Marcos; Fernandes, Fátima; Pinho, P. Guedes de; Andrade, Paula B.; Pereira, J.A.; Valentão, PatríciaBrassica rapa var. rapa L. (turnip) is highly appreciated and consumed by human. In this work, the volatile profile of B. rapa var. rapa was studied during the maturation process. The volatiles of seeds, sprouts with 6 and 9 days, and adult plant were determined using headspace solid-phase microextraction (HS-SPME) combined with gas chromatography/ion trap-mass spectrometry (GC/IT-MS). Several constituents, including alcohols, aldehydes, esters, ketones, norisoprenoids, nitrogen and sulphur compounds were characterized, totalizing 64 compounds. Isothiocyanates are the main volatiles in all matrices, being 3-butenyl isothiocyanate the major compound. Qualitative and quantitative differences were found among the analysed materials. Nitrogen and sulphur compounds decreased during the maturation process, while terpenes, aldehydes, norisoprenoids and ester compounds were present in higher amounts during germination, especially in sprouts with 9 days of development.
- 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.
- Pieris brassicae excrements: cytological effectsPublication . Fernandes, Fátima; Teixeira, João Paulo Fernandes; Taveira, Marcos; Sousa, Carla; Costa, Solange; Coelho, Patrícia Clara dos Santos; Valentão, Patrícia; Remião, Fernando; Pereira, J.A.; Andrade, Paula B.Attention has been focused on identifying naturally occurring compounds with anticarcinogenic activity. Epidemiological data evidence the protective role of Brassica species, especially due to their phenolics and glucosinolates. Pieris brassicae, an insect whose larvae constitutes a frequent pest of Brassica species, has the capacity to uptake, metabolize and excrete these phytochemicals by the faeces. Phenolics composition of excrements from P. brassicae reared on Brassica oleracea var. acephala presents flavonoids (sulfated and glycosilated), some of them not detected in host plant [1]. Their volatiles profile shows compounds belonging to different classes, with especial attention to terpenes and glucosinolates breakdown products (sulfur and nitrogen compounds) [2]. Furthermore, this matrix already revealed to have antioxidative properties [1].
- Screening of antioxidant compounds during sprouting of Brassica oleracea L. var. costata DCPublication . Sousa, Carla; Lopes, Graciliana; Pereira, David M.; Taveira, Marcos; Valentão, Patrícia; Seabra, Rosa M.; Pereira, J.A.; Baptista, Paula; Ferreres, Frederico; Andrade, Paula B.The changes in antioxidant compounds of Brassica oleracea L. var. costata DC seeds were monitored during the first twelve days of seedling development. Sprouts were screened at time intervals of two days for phenolic compounds and organic acids. The identified phenolic compounds included esters of sinapic acid with glucose, gentiobiose and kaempferol, as well as sinapoylcholine. The organic acids were oxalic, aconitic, citric, pyruvic, malic, shikimic, and fumaric acids. During germination, a depletion of phenolic compounds was observed, although no qualitative changes were seen. Among individual compounds, kaempferol, choline and glucose esters of sinapic acid showed a marked decrease between days two and six, whereas the changes in gentiobiose esters of sinapic acid were smaller. The total organic acids content increased rapidly during the first four days, with less significant variations thereafter. Malic acid, the major organic acid found in sprouts, greatly contributed to this result though oxalic, pyruvic, and fumaric acids also increased in the same manner. In contrast, aconitic, citric and shikimic acids showed decreases between days two and twelve of germination.
- Screening of antioxidant phenolic compounds produced by in vitro shoots of Brassica oleracea L. var. costata DC.Publication . Ferreres, Frederico; Sousa, Carla; Pereira, David M.; Valentão, Patrícia; Taveira, Marcos; Martins, Anabela; Pereira, J.A.; Seabra, Rosa M.; Andrade, Paula B.The phenolic compounds produced by in vitro shoots of Brassica oleracea L. var. costata DC were screened by HPLC-DAD-MS/MS. Thirty seven compounds were characterized, which included chlorogenic acids, flavonoids (the majority of them were hydroxycinnamic acid esters of kaempferol and quercetin glycosides) and hydroxycinnamic acyl glycosides (with predominance of synapoyl gentiobiosides). The antioxidant capacity of the shoots was assessed against DPPH radical and two reactive oxygen species (superoxide radical and hypochlorous acid). A strong concentrationdependent antioxidative capacity was verified in the DPPH and superoxide radicals assays, but a reduced effect was noticed against hypochlorous acid. The results obtained indicate that the in vitro production of B. oleracea var. costata shoots can become important in the obtention of a noticeable dietary source of compounds with health protective potential.