Carla Sousa - Academia.edu (original) (raw)

Papers by Carla Sousa

Food Chemistry, 2007

The phenolic compounds and organic acids of turnip (Brassica rapa var. rapa L.) edible parts (lea... more 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-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.

Journal of Agricultural and Food Chemistry, 2005

A phytochemical study was undertaken on tronchuda cabbage (Brassica oleracea L. var. costata DC) ... more A phytochemical study was undertaken on tronchuda cabbage (Brassica oleracea L. var. costata DC) cultivated under conventional and organic practices and collected at different times. Six organic acids (aconitic, citric, ascorbic, malic, shikimic, and fumaric acids) were identified and quantified by HPLC-UV. Qualitative and quantitative differences were noted between internal and external leaves. Analysis of the phenolics of the internal leaves was achieved by HPLC-DAD, and the phenolic profile obtained was revealed to be distinct from that of the external leaves. By this means were identified and quantified 11 compounds: 3isomeric forms of 1,2-disinapoylgentiobiose, 1-sinapoyl-2-feruloylgentiobiose, 1,2,2′-trisinapoylgentiobiose, and 1,2′-disinapoyl-2-feruloylgentiobiose. In general, internal leaves exhibited more constant chemical profiles. We are grateful to the Fundação para a Ciência e Tecnologia (POCI/AGR/57399/2004) for financial support of this work.

Journal of Agricultural and Food Chemistry, 2008

The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of ... more The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of the reactive nitrogen species nitric oxide and peroxynitrite was investigated. The aqueous extracts obtained from tronchuda cabbage seeds and from its external and internal leaves exhibited a concentration dependent scavenging capacity. The antioxidant potential observed against the two reactive species was as follows: seeds > external leaves > internal leaves. In order to establish a possible correlation with the chemical composition of the extracts, the activity of ascorbic and sinapic acids and kaempferol 3-O-rutinoside was also studied. Among the compounds tested, sinapic acid showed the strongest antioxidant activity against both species. . We are grateful to Fundação para a Ciência e a Tecnologia (POCI/AGR/57399/2004) for financial support of this work.

Food Chemistry, 2008

Two Brassica oleracea varieties (B. oleracea L. var. costata DC and B. oleracea L. var. acephala)... more 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.

Food Chemistry, 2006

The ability of the aqueous extract of tronchuda cabbage (Brassica oleracea L. var. costata DC) ex... more The ability of the aqueous extract of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves to act as a scavenger of DPPH Å 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.

European Food Research and Technology, 2006

A phytochemical study was undertaken on the internal leaves of tronchuda cabbage (Brassica olerac... more 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 HPLC-DAD-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 gluc-oside acid, kaempferol 3-O-(sinapoyl)-sophoroside-7-O-glucoside, kaempferol 3-O-(feruloyl)-sophoroside-7-O-glucoside, 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-ferul-oylgentiobiose. 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.

Phytochemical Analysis, 2005

Phenolic acids and flavonols of nine leaf and three root samples of Boerhaavia diffusa L., collec... more Phenolic acids and flavonols of nine leaf and three root samples of Boerhaavia diffusa L., collected at different locations and subjected to several drying procedures, were characterised by reversed-phase HPLC-PADESI/MS for the first time. Ten phenolic compounds were identified: 3,4-dihydroxy-5-methoxycinnamoyl-rhamnoside, quercetin 3-O-rhamnosyl(16)galactoside (quercetin 3-O-robinobioside), quercetin 3-O-(2″-rhamnosyl)-robinobioside, kaempferol 3-O-(2″-rhamnosyl)-robinobioside, 3,5,4′-trihydroxy-6,7-dimethoxyflavone 3-O-galactosyl(12)glucoside [eupalitin 3-O-galactosyl(12)glucoside], caffeoyltartaric acid, kaempferol 3-O-robinobioside, eupalitin 3-O-galactoside, quercetin and kaempferol. Quantification was achieved by HPLC-PAD and two phenolic patterns were found for the leaves, in which quercetin 3-O-robinobioside or quercetin 3-O-(2″-rhamnosyl)-robinobioside was the major compound. Caffeoyltartaric acid was only present in the root material where it represented the main phenolic constituent. The results obtained demonstrated that the geographical origin (particularly the nature of the soil), but not the drying process, influences the phenolic composition. Copyright © 2005 John Wiley & Sons, Ltd.

Journal of Agricultural and Food Chemistry, 2005

Glycosylated kaempferol derivatives from the external leaves of tronchuda cabbage (Brassica olera... more Glycosylated kaempferol derivatives from the external leaves of tronchuda cabbage (Brassica oleracea L. var. costata DC) characterized by reversed-phase HPLC-DAD-MS/MS-ESI were kaempferol 3-Okaempferol 3-O-glucoside. These acylated derivatives are reported for the first time in nature, with the exception of kaempferol 3-O-(sinapoyl)sophoroside. Quantification of the identified compounds was achieved by HPLC-DAD and carried out in samples cultivated under conventional or organic practices and collected at different times. In general, samples from organic production exhibited higher total phenolics content than those from conventional practices collected in the same period. . We are grateful to Fundação para a Ciência e Tecnologia (POCTI/AGR/57399/2004) for financial support of this work.

Journal of Agricultural and Food Chemistry, 2008

A field experiment was carried out to investigate the effect of fertilization level on the phenol... more A field experiment was carried out to investigate the effect of fertilization level on the phenolic composition of tronchuda cabbage (Brassica oleracea L. var. costata DC) external and internal leaves. Eight different plots were constituted: a control without fertilization, one with organic matter, and six experiments with conventional fertilizers (nitrogen, boron, and sulfur, two levels each). The phenolic compounds were analyzed by reversed-phase HPLC-DAD. External and internal leaves revealed distinct qualitative composition. In the internal leaves were found 15 phenolics (5 kaempferol and 10 cinnamic acid derivatives), whereas the external leaves presented 3-p-coumaroylquinic acid and 13 kaempferol derivatives. Principal component analysis (PCA) was applied to assess the relationships between phenolic compounds, agronomical practices, and harvesting time. Samples obtained with conventional practices were quite effectively separated from organic samples, for both types of leaves. In general, samples developed without any fertilization presented the highest phenolics amounts: external and internal leaves contained 1.4-and 4.6-fold more phenolic compounds than the ones that received conventional fertilizer, respectively, and the internal leaves presented 2.4 times more phenolics than the ones grown with organic amendment. Additionally, samples from organic production exhibited higher total phenolics content than those from conventional practices, collected at the same time. Samples harvested first were revealed to be distinct from the ones collected later. The results show that it is possible to grow tronchuda cabbage without excess fertilizers, with highest amounts of phenolics and reduced environment contamination.

Food Chemistry, 2007

The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of ... more The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of the reactive nitrogen species nitric oxide and peroxynitrite was investigated. The aqueous extracts obtained from tronchuda cabbage seeds and from its external and internal leaves exhibited a concentration dependent scavenging capacity. The antioxidant potential observed against the two reactive species was as follows: seeds > external leaves > internal leaves. In order to establish a possible correlation with the chemical composition of the extracts, the activity of ascorbic and sinapic acids and kaempferol 3-O-rutinoside was also studied. Among the compounds tested, sinapic acid showed the strongest antioxidant activity against both species. . We are grateful to Fundação para a Ciência e a Tecnologia (POCI/AGR/57399/2004) for financial support of this work.

Food Chemistry, 2007

The phenolic compounds and organic acids of turnip (Brassica rapa var. rapa L.) edible parts (lea... more 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-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.

Journal of Agricultural and Food Chemistry, 2005

A phytochemical study was undertaken on tronchuda cabbage (Brassica oleracea L. var. costata DC) ... more A phytochemical study was undertaken on tronchuda cabbage (Brassica oleracea L. var. costata DC) cultivated under conventional and organic practices and collected at different times. Six organic acids (aconitic, citric, ascorbic, malic, shikimic, and fumaric acids) were identified and quantified by HPLC-UV. Qualitative and quantitative differences were noted between internal and external leaves. Analysis of the phenolics of the internal leaves was achieved by HPLC-DAD, and the phenolic profile obtained was revealed to be distinct from that of the external leaves. By this means were identified and quantified 11 compounds: 3isomeric forms of 1,2-disinapoylgentiobiose, 1-sinapoyl-2-feruloylgentiobiose, 1,2,2′-trisinapoylgentiobiose, and 1,2′-disinapoyl-2-feruloylgentiobiose. In general, internal leaves exhibited more constant chemical profiles. We are grateful to the Fundação para a Ciência e Tecnologia (POCI/AGR/57399/2004) for financial support of this work.

Journal of Agricultural and Food Chemistry, 2008

The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of ... more The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of the reactive nitrogen species nitric oxide and peroxynitrite was investigated. The aqueous extracts obtained from tronchuda cabbage seeds and from its external and internal leaves exhibited a concentration dependent scavenging capacity. The antioxidant potential observed against the two reactive species was as follows: seeds > external leaves > internal leaves. In order to establish a possible correlation with the chemical composition of the extracts, the activity of ascorbic and sinapic acids and kaempferol 3-O-rutinoside was also studied. Among the compounds tested, sinapic acid showed the strongest antioxidant activity against both species. . We are grateful to Fundação para a Ciência e a Tecnologia (POCI/AGR/57399/2004) for financial support of this work.

Food Chemistry, 2008

Two Brassica oleracea varieties (B. oleracea L. var. costata DC and B. oleracea L. var. acephala)... more 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.

Food Chemistry, 2006

The ability of the aqueous extract of tronchuda cabbage (Brassica oleracea L. var. costata DC) ex... more The ability of the aqueous extract of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves to act as a scavenger of DPPH Å 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.

European Food Research and Technology, 2006

A phytochemical study was undertaken on the internal leaves of tronchuda cabbage (Brassica olerac... more 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 HPLC-DAD-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 gluc-oside acid, kaempferol 3-O-(sinapoyl)-sophoroside-7-O-glucoside, kaempferol 3-O-(feruloyl)-sophoroside-7-O-glucoside, 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-ferul-oylgentiobiose. 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.

Phytochemical Analysis, 2005

Phenolic acids and flavonols of nine leaf and three root samples of Boerhaavia diffusa L., collec... more Phenolic acids and flavonols of nine leaf and three root samples of Boerhaavia diffusa L., collected at different locations and subjected to several drying procedures, were characterised by reversed-phase HPLC-PADESI/MS for the first time. Ten phenolic compounds were identified: 3,4-dihydroxy-5-methoxycinnamoyl-rhamnoside, quercetin 3-O-rhamnosyl(16)galactoside (quercetin 3-O-robinobioside), quercetin 3-O-(2″-rhamnosyl)-robinobioside, kaempferol 3-O-(2″-rhamnosyl)-robinobioside, 3,5,4′-trihydroxy-6,7-dimethoxyflavone 3-O-galactosyl(12)glucoside [eupalitin 3-O-galactosyl(12)glucoside], caffeoyltartaric acid, kaempferol 3-O-robinobioside, eupalitin 3-O-galactoside, quercetin and kaempferol. Quantification was achieved by HPLC-PAD and two phenolic patterns were found for the leaves, in which quercetin 3-O-robinobioside or quercetin 3-O-(2″-rhamnosyl)-robinobioside was the major compound. Caffeoyltartaric acid was only present in the root material where it represented the main phenolic constituent. The results obtained demonstrated that the geographical origin (particularly the nature of the soil), but not the drying process, influences the phenolic composition. Copyright © 2005 John Wiley & Sons, Ltd.

Journal of Agricultural and Food Chemistry, 2005

Glycosylated kaempferol derivatives from the external leaves of tronchuda cabbage (Brassica olera... more Glycosylated kaempferol derivatives from the external leaves of tronchuda cabbage (Brassica oleracea L. var. costata DC) characterized by reversed-phase HPLC-DAD-MS/MS-ESI were kaempferol 3-Okaempferol 3-O-glucoside. These acylated derivatives are reported for the first time in nature, with the exception of kaempferol 3-O-(sinapoyl)sophoroside. Quantification of the identified compounds was achieved by HPLC-DAD and carried out in samples cultivated under conventional or organic practices and collected at different times. In general, samples from organic production exhibited higher total phenolics content than those from conventional practices collected in the same period. . We are grateful to Fundação para a Ciência e Tecnologia (POCTI/AGR/57399/2004) for financial support of this work.

Journal of Agricultural and Food Chemistry, 2008

A field experiment was carried out to investigate the effect of fertilization level on the phenol... more A field experiment was carried out to investigate the effect of fertilization level on the phenolic composition of tronchuda cabbage (Brassica oleracea L. var. costata DC) external and internal leaves. Eight different plots were constituted: a control without fertilization, one with organic matter, and six experiments with conventional fertilizers (nitrogen, boron, and sulfur, two levels each). The phenolic compounds were analyzed by reversed-phase HPLC-DAD. External and internal leaves revealed distinct qualitative composition. In the internal leaves were found 15 phenolics (5 kaempferol and 10 cinnamic acid derivatives), whereas the external leaves presented 3-p-coumaroylquinic acid and 13 kaempferol derivatives. Principal component analysis (PCA) was applied to assess the relationships between phenolic compounds, agronomical practices, and harvesting time. Samples obtained with conventional practices were quite effectively separated from organic samples, for both types of leaves. In general, samples developed without any fertilization presented the highest phenolics amounts: external and internal leaves contained 1.4-and 4.6-fold more phenolic compounds than the ones that received conventional fertilizer, respectively, and the internal leaves presented 2.4 times more phenolics than the ones grown with organic amendment. Additionally, samples from organic production exhibited higher total phenolics content than those from conventional practices, collected at the same time. Samples harvested first were revealed to be distinct from the ones collected later. The results show that it is possible to grow tronchuda cabbage without excess fertilizers, with highest amounts of phenolics and reduced environment contamination.

Food Chemistry, 2007

The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of ... more The ability of tronchuda cabbage (Brassica oleracea L. var. costata DC) to act as a scavenger of the reactive nitrogen species nitric oxide and peroxynitrite was investigated. The aqueous extracts obtained from tronchuda cabbage seeds and from its external and internal leaves exhibited a concentration dependent scavenging capacity. The antioxidant potential observed against the two reactive species was as follows: seeds > external leaves > internal leaves. In order to establish a possible correlation with the chemical composition of the extracts, the activity of ascorbic and sinapic acids and kaempferol 3-O-rutinoside was also studied. Among the compounds tested, sinapic acid showed the strongest antioxidant activity against both species. . We are grateful to Fundação para a Ciência e a Tecnologia (POCI/AGR/57399/2004) for financial support of this work.