Marcos Taveira | Universidade do Porto (original) (raw)

Papers by Marcos Taveira

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.

Tronchuda cabbage (Brassica o/eracea l. var. costata DC) exhibils large floppy leaves, which are ... more Tronchuda cabbage (Brassica o/eracea l. var. costata DC) exhibils large floppy leaves, which are close logelher, round, smooO, and slightly notched ai lhe margins. Ils dark green external leaves are ralher biller and lough and are usuaUy prepared by boiling. The internal leaves are pare yeJlow, tender and sweeler Ihan lhe externaJ anes, being cansumed raw ar, mast usually, caaked. A phylachemical sludy was undertaken on Ihis cabbage, cultivated under ten distincl fertilizatian regimes (applicalian of Iwa diflerenl leveIs af nllr0gen, thrae ...

The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and... more The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and recto and with the prevention of cardiovascular diseases. The most consumed Brassica species in Portugal is the tronchuda cabbage or Portuguese cabbage (Brassica oleracea var. costata DC). This study concerned the characterization of chemical composition (phenolics and organic acids) and the evaluation of the antioxidant potential of tronchuda cabbage. Seeds, sprouts, internal and external leaves were analysed. To evaluate the antioxidant potential, the ability of tronchuda cabbage materials to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid) was investigated. Additionally, it was found that Pieris brassicae, a plague infesting Brassica cultures, exhibits interesting antioxidant potential, once it sequesters, metabolizes and accumulates phenolics. The possibility of commercialization of standardized aqueous extracts of Brassica o...

Headspace – solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrome... more Headspace – solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry-ion trap detector (GC-MSIT) has been used to characterize volatile compounds in several natural matrices. A great number of fibres with different polarities are commercially available, allowing the screening of the highest possible number of components. HS-SPME has several advantages, such as the condensation of extraction, concentration and sample introduction into a single step. In this extraction technique, a medium polarity fibre for flavours (carboxen/polydimethylsiloxane or divinylbenzene/polydimethylsiloxane) is usually used in order to achieve equilibrium between non-polar and polar compounds, thus increasing the screening range. The traditional methodologies using organic solvents, namely dichloromethane (DCM), allow the determination of a considerable number of volatile and semi-volatile compounds in natural matrices. In this review, the main theoretical points involved in ...

In this work were studied the phenolic composition of in vitro material (shoots, calli, and roots... more In 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.

Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or p... more Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or progression of several neurodegenerative diseases. The aim of this study was to investigate for the first time whether both extracts from tomato plant (Lycopersicon esculentum Mill.) leaves and their isolated steroidal alkaloids (tomatine and tomatidine) afford neuroprotective effect against glutamate-induced toxicity in SH-SY5Y neuroblastoma cells and to elucidate the mechanisms underlying this protection. Steroidal alkaloids from tomato are well known for their cholinesterases' inhibitory capacity and the results showed that both purified extracts and isolated compounds, at non-toxic concentrations for gastric (AGS), intestinal (Caco-2) and neuronal (SH-SY5Y) cells, have the capacity to preserve mitochondria membrane potential and to decrease reactive oxygen species levels of SH-SY5Y glutamate-insulted cells. Moreover, the use of specific antagonists of cholinergic receptors allowed observing that tomatine and tomatidine can interact with nicotinic receptors, specifically with the ␣7 type. No effect on muscarinic receptors was noticed. In addition to the selective cholinesterases' inhibition revealed by the compounds/extracts, these results provide novel and important insights into their neuroprotective mechanism. This work also demystifies the applicability of these compounds in therapeutics, by demonstrating that their toxicity was overestimated for long time.

Journal of food science and technology, 2017

The aim of this work was to evaluate the quality of 16 honey samples from Castelo Branco region (... more The aim of this work was to evaluate the quality of 16 honey samples from Castelo Branco region (Portugal). Twelve are monofloral from Calluna vulgaris, Erica, Lavandula, Echium and Campanula. The mean values obtained for physicochemical parameters were: 3.82 pH; 16.80% moisture; 81.6°Brix; 0.21% ash; 357.6 μS cm(-1) electrical conductivity; 33.7 meq/kg free acidity; 5.7 meq/kg lactonic acidity; 39.3 meq/kg total acidity; 9.11 mg/kg HMF; 21.3 IN invertase and 9.0° Gothe for diastase activities. The results indicate a good quality, adequate processing, good maturity and freshness of honey. Additionally, the determination of mineral contents revealed that the K was the major element. Mean values obtained were (mg/kg): Ca, 28.36; K, 701.87; Mg, 74.00; Na, 31.04; Fe, 097; Cu, 0.65; Zn, 1.23; Mn, 2.78 and P, 48.80. Among the overall determined parameters, CB2 stands out by its high values in minerals, pH, moisture, ash, electrical conductivity and enzyme activity.

Journal of Agricultural and Food Chemistry, Sep 8, 2010

Journal of Agricultural and Food Chemistry, 2010

RSC Adv., 2015

The inclusion of marine organisms in the diet is gaining importance due to their richness in heal... more The inclusion of marine organisms in the diet is gaining importance due to their richness in health beneficial nutrients.

Microchemical Journal, Nov 30, 2009

Brassica rapa var. rapa L.(turnip) is highly appreciated and consumed by human. In this work, the... more Brassica 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, ...

Phytochemistry …, 2008

In: Phytochemistry Research Progress ISBN: 978-1-60456-232-3 Editor: Takumi Matsumoto, pp. 87-113... more In: Phytochemistry Research Progress ISBN: 978-1-60456-232-3 Editor: Takumi Matsumoto, pp. 87-113© 2008 Nova Science Publishers, Inc. Chapter V Recent Advances in Brassica oleracea and Brassica rapa Varieties Phenolics Paula B. Andrade"'*, Patricia Valentdo", Carla ...

Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or p... more Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or progression of several neurodegenerative diseases. The aim of this study was to investigate for the first time whether both extracts from tomato plant (Lycopersicon esculentum Mill.) leaves and their isolated steroidal alkaloids (tomatine and tomatidine) afford neuroprotective effect against glutamate-induced toxicity in SH-SY5Y neuroblastoma cells and to elucidate the mechanisms underlying this protection. Steroidal alkaloids from tomato are well known for their cholinesterases' inhibitory capacity and the results showed that both purified extracts and isolated compounds, at non-toxic concentrations for gastric (AGS), intestinal (Caco-2) and neuronal (SH-SY5Y) cells, have the capacity to preserve mitochondria membrane potential and to decrease reactive oxygen species levels of SH-SY5Y glutamate-insulted cells. Moreover, the use of specific antagonists of cholinergic receptors allowed observing that tomatine and tomatidine can interact with nicotinic receptors, specifically with the ␣7 type. No effect on muscarinic receptors was noticed. In addition to the selective cholinesterases' inhibition revealed by the compounds/extracts, these results provide novel and important insights into their neuroprotective mechanism. This work also demystifies the applicability of these compounds in therapeutics, by demonstrating that their toxicity was overestimated for long time.

The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and... more The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and recto and with the prevention of cardiovascular diseases. The most consumed Brassica species in Portugal is the tronchuda cabbage or Portuguese cabbage (Brassica oleracea var. costata DC). This study concerned the characterization of chemical composition (phenolics and organic acids) and the evaluation of the antioxidant potential of tronchuda cabbage. Seeds, sprouts, internal and external leaves were analysed.

Rapid …, Jan 1, 2011

High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage ... more High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage mass spectrometry (HPLC-DAD-ESI-MS n ) is considered to be a very valuable tool for the characterization of compounds found in trace amounts in natural matrices, as their previous isolation and clean-up steps can be avoided. Micro-scale separation increases the potential of this analytical technique, allowing the determination of compounds in reduced samples. Spodoptera littoralis represents a major challenge to Solanaceae plants, as it is one of the most deleterious pests. The S. littoralis/Lycopersicon esculentum system was studied for the first time concerning glycoalkaloids and phenolics. Using HPLC-DAD-ESI-MS n we were able to characterize 15 phenolic compounds in L. esculentum leaves. Nine of them are reported for the first time. Some differences were found between leaves of cerasiforme and 'Bull's heart' varieties. However, in the materials of S. littoralis (larvae, adults, exuviae and excrements) reared in both L. esculentum leaves no phenolics were identified. α-Tomatine was the main glycoalkaloid in the host plant. The glycoalkaloid composition of the different S. littoralis materials was distinct, with α-tomatine and dehydrotomatine being the main detected compounds in larvae and excrements. These results add knowledge to the ecological interaction in this insect/plant duo, for which it is hard to obtain considerable sample amounts.

Food Chemistry, Jan 1, 2012

Lycopersicon esculentum leaves, usually considered as a by-product of tomato production, present ... more Lycopersicon esculentum leaves, usually considered as a by-product of tomato production, present several bioactive compounds of interest for industries like food, pharmaceutical and cosmetics. Nevertheless, before industrial application, suitable methods to identify and quantify those metabolites should be developed. In this study agitation with aqueous methanol was used for phenolic compounds extraction. Solid-phase extraction (SPE) was performed as the purification step before alkaloids analysis. Among the SPE sorbents tested, sulphonic acid bonded silica with H + counterion (SCX) proved to be the most efficient one for removing interfering components. Fifteen phenolics and four steroidic alkaloids were identified in 35 and 20 min analysis, respectively. The optimised methods were validated, revealing to be accurate, fast, simple and sensitive. Thus, these methods represent an easy and fast analytical approach, using equipment available in almost laboratory, which render them to be appropriate for routine analysis.

Rapid communications in mass spectrometry : RCM, Jan 1, 2011

High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage ... more High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage mass spectrometry (HPLC-DAD-ESI-MSn) is considered to be a very valuable tool for the characterization of compounds found in trace amounts in natural matrices, as their previous isolation and clean-up steps can be avoided. Micro-scale separation increases the potential of this analytical technique, allowing the determination of compounds in reduced samples. Spodoptera littoralis represents a major challenge to Solanaceae plants, as it is one of the most deleterious pests. The S. littoralis/Lycopersicon esculentum system was studied for the first time concerning glycoalkaloids and phenolics. Using HPLC-DAD-ESI-MSn we were able to characterize 15 phenolic compounds in L. esculentum leaves. Nine of them are reported for the first time. Some differences were found between leaves of cerasiforme and 'Bull's heart' varieties. However, in the materials of S. littoralis (larvae, adults, exuviae and excrements) reared in both L. esculentum leaves no phenolics were identified. α-Tomatine was the main glycoalkaloid in the host plant. The glycoalkaloid composition of the different S. littoralis materials was distinct, with α-tomatine and dehydrotomatine being the main detected compounds in larvae and excrements. These results add knowledge to the ecological interaction in this insect/plant duo, for which it is hard to obtain considerable sample amounts. Copyright © 2011 John Wiley & Sons, Ltd.

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.

Tronchuda cabbage (Brassica o/eracea l. var. costata DC) exhibils large floppy leaves, which are ... more Tronchuda cabbage (Brassica o/eracea l. var. costata DC) exhibils large floppy leaves, which are close logelher, round, smooO, and slightly notched ai lhe margins. Ils dark green external leaves are ralher biller and lough and are usuaUy prepared by boiling. The internal leaves are pare yeJlow, tender and sweeler Ihan lhe externaJ anes, being cansumed raw ar, mast usually, caaked. A phylachemical sludy was undertaken on Ihis cabbage, cultivated under ten distincl fertilizatian regimes (applicalian of Iwa diflerenl leveIs af nllr0gen, thrae ...

The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and... more The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and recto and with the prevention of cardiovascular diseases. The most consumed Brassica species in Portugal is the tronchuda cabbage or Portuguese cabbage (Brassica oleracea var. costata DC). This study concerned the characterization of chemical composition (phenolics and organic acids) and the evaluation of the antioxidant potential of tronchuda cabbage. Seeds, sprouts, internal and external leaves were analysed. To evaluate the antioxidant potential, the ability of tronchuda cabbage materials to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid) was investigated. Additionally, it was found that Pieris brassicae, a plague infesting Brassica cultures, exhibits interesting antioxidant potential, once it sequesters, metabolizes and accumulates phenolics. The possibility of commercialization of standardized aqueous extracts of Brassica o...

Headspace – solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrome... more Headspace – solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry-ion trap detector (GC-MSIT) has been used to characterize volatile compounds in several natural matrices. A great number of fibres with different polarities are commercially available, allowing the screening of the highest possible number of components. HS-SPME has several advantages, such as the condensation of extraction, concentration and sample introduction into a single step. In this extraction technique, a medium polarity fibre for flavours (carboxen/polydimethylsiloxane or divinylbenzene/polydimethylsiloxane) is usually used in order to achieve equilibrium between non-polar and polar compounds, thus increasing the screening range. The traditional methodologies using organic solvents, namely dichloromethane (DCM), allow the determination of a considerable number of volatile and semi-volatile compounds in natural matrices. In this review, the main theoretical points involved in ...

In this work were studied the phenolic composition of in vitro material (shoots, calli, and roots... more In 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.

Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or p... more Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or progression of several neurodegenerative diseases. The aim of this study was to investigate for the first time whether both extracts from tomato plant (Lycopersicon esculentum Mill.) leaves and their isolated steroidal alkaloids (tomatine and tomatidine) afford neuroprotective effect against glutamate-induced toxicity in SH-SY5Y neuroblastoma cells and to elucidate the mechanisms underlying this protection. Steroidal alkaloids from tomato are well known for their cholinesterases' inhibitory capacity and the results showed that both purified extracts and isolated compounds, at non-toxic concentrations for gastric (AGS), intestinal (Caco-2) and neuronal (SH-SY5Y) cells, have the capacity to preserve mitochondria membrane potential and to decrease reactive oxygen species levels of SH-SY5Y glutamate-insulted cells. Moreover, the use of specific antagonists of cholinergic receptors allowed observing that tomatine and tomatidine can interact with nicotinic receptors, specifically with the ␣7 type. No effect on muscarinic receptors was noticed. In addition to the selective cholinesterases' inhibition revealed by the compounds/extracts, these results provide novel and important insights into their neuroprotective mechanism. This work also demystifies the applicability of these compounds in therapeutics, by demonstrating that their toxicity was overestimated for long time.

Journal of food science and technology, 2017

The aim of this work was to evaluate the quality of 16 honey samples from Castelo Branco region (... more The aim of this work was to evaluate the quality of 16 honey samples from Castelo Branco region (Portugal). Twelve are monofloral from Calluna vulgaris, Erica, Lavandula, Echium and Campanula. The mean values obtained for physicochemical parameters were: 3.82 pH; 16.80% moisture; 81.6°Brix; 0.21% ash; 357.6 μS cm(-1) electrical conductivity; 33.7 meq/kg free acidity; 5.7 meq/kg lactonic acidity; 39.3 meq/kg total acidity; 9.11 mg/kg HMF; 21.3 IN invertase and 9.0° Gothe for diastase activities. The results indicate a good quality, adequate processing, good maturity and freshness of honey. Additionally, the determination of mineral contents revealed that the K was the major element. Mean values obtained were (mg/kg): Ca, 28.36; K, 701.87; Mg, 74.00; Na, 31.04; Fe, 097; Cu, 0.65; Zn, 1.23; Mn, 2.78 and P, 48.80. Among the overall determined parameters, CB2 stands out by its high values in minerals, pH, moisture, ash, electrical conductivity and enzyme activity.

Journal of Agricultural and Food Chemistry, Sep 8, 2010

Journal of Agricultural and Food Chemistry, 2010

RSC Adv., 2015

The inclusion of marine organisms in the diet is gaining importance due to their richness in heal... more The inclusion of marine organisms in the diet is gaining importance due to their richness in health beneficial nutrients.

Microchemical Journal, Nov 30, 2009

Brassica rapa var. rapa L.(turnip) is highly appreciated and consumed by human. In this work, the... more Brassica 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, ...

Phytochemistry …, 2008

In: Phytochemistry Research Progress ISBN: 978-1-60456-232-3 Editor: Takumi Matsumoto, pp. 87-113... more In: Phytochemistry Research Progress ISBN: 978-1-60456-232-3 Editor: Takumi Matsumoto, pp. 87-113© 2008 Nova Science Publishers, Inc. Chapter V Recent Advances in Brassica oleracea and Brassica rapa Varieties Phenolics Paula B. Andrade"'*, Patricia Valentdo", Carla ...

Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or p... more Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or progression of several neurodegenerative diseases. The aim of this study was to investigate for the first time whether both extracts from tomato plant (Lycopersicon esculentum Mill.) leaves and their isolated steroidal alkaloids (tomatine and tomatidine) afford neuroprotective effect against glutamate-induced toxicity in SH-SY5Y neuroblastoma cells and to elucidate the mechanisms underlying this protection. Steroidal alkaloids from tomato are well known for their cholinesterases' inhibitory capacity and the results showed that both purified extracts and isolated compounds, at non-toxic concentrations for gastric (AGS), intestinal (Caco-2) and neuronal (SH-SY5Y) cells, have the capacity to preserve mitochondria membrane potential and to decrease reactive oxygen species levels of SH-SY5Y glutamate-insulted cells. Moreover, the use of specific antagonists of cholinergic receptors allowed observing that tomatine and tomatidine can interact with nicotinic receptors, specifically with the ␣7 type. No effect on muscarinic receptors was noticed. In addition to the selective cholinesterases' inhibition revealed by the compounds/extracts, these results provide novel and important insights into their neuroprotective mechanism. This work also demystifies the applicability of these compounds in therapeutics, by demonstrating that their toxicity was overestimated for long time.

The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and... more The genus Brassica is related with the prevention of carcinomas, especially of stomach, colon and recto and with the prevention of cardiovascular diseases. The most consumed Brassica species in Portugal is the tronchuda cabbage or Portuguese cabbage (Brassica oleracea var. costata DC). This study concerned the characterization of chemical composition (phenolics and organic acids) and the evaluation of the antioxidant potential of tronchuda cabbage. Seeds, sprouts, internal and external leaves were analysed.

Rapid …, Jan 1, 2011

High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage ... more High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage mass spectrometry (HPLC-DAD-ESI-MS n ) is considered to be a very valuable tool for the characterization of compounds found in trace amounts in natural matrices, as their previous isolation and clean-up steps can be avoided. Micro-scale separation increases the potential of this analytical technique, allowing the determination of compounds in reduced samples. Spodoptera littoralis represents a major challenge to Solanaceae plants, as it is one of the most deleterious pests. The S. littoralis/Lycopersicon esculentum system was studied for the first time concerning glycoalkaloids and phenolics. Using HPLC-DAD-ESI-MS n we were able to characterize 15 phenolic compounds in L. esculentum leaves. Nine of them are reported for the first time. Some differences were found between leaves of cerasiforme and 'Bull's heart' varieties. However, in the materials of S. littoralis (larvae, adults, exuviae and excrements) reared in both L. esculentum leaves no phenolics were identified. α-Tomatine was the main glycoalkaloid in the host plant. The glycoalkaloid composition of the different S. littoralis materials was distinct, with α-tomatine and dehydrotomatine being the main detected compounds in larvae and excrements. These results add knowledge to the ecological interaction in this insect/plant duo, for which it is hard to obtain considerable sample amounts.

Food Chemistry, Jan 1, 2012

Lycopersicon esculentum leaves, usually considered as a by-product of tomato production, present ... more Lycopersicon esculentum leaves, usually considered as a by-product of tomato production, present several bioactive compounds of interest for industries like food, pharmaceutical and cosmetics. Nevertheless, before industrial application, suitable methods to identify and quantify those metabolites should be developed. In this study agitation with aqueous methanol was used for phenolic compounds extraction. Solid-phase extraction (SPE) was performed as the purification step before alkaloids analysis. Among the SPE sorbents tested, sulphonic acid bonded silica with H + counterion (SCX) proved to be the most efficient one for removing interfering components. Fifteen phenolics and four steroidic alkaloids were identified in 35 and 20 min analysis, respectively. The optimised methods were validated, revealing to be accurate, fast, simple and sensitive. Thus, these methods represent an easy and fast analytical approach, using equipment available in almost laboratory, which render them to be appropriate for routine analysis.

Rapid communications in mass spectrometry : RCM, Jan 1, 2011

High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage ... more High-performance liquid chromatography-diode array detection-electrospray ionization multi-stage mass spectrometry (HPLC-DAD-ESI-MSn) is considered to be a very valuable tool for the characterization of compounds found in trace amounts in natural matrices, as their previous isolation and clean-up steps can be avoided. Micro-scale separation increases the potential of this analytical technique, allowing the determination of compounds in reduced samples. Spodoptera littoralis represents a major challenge to Solanaceae plants, as it is one of the most deleterious pests. The S. littoralis/Lycopersicon esculentum system was studied for the first time concerning glycoalkaloids and phenolics. Using HPLC-DAD-ESI-MSn we were able to characterize 15 phenolic compounds in L. esculentum leaves. Nine of them are reported for the first time. Some differences were found between leaves of cerasiforme and 'Bull's heart' varieties. However, in the materials of S. littoralis (larvae, adults, exuviae and excrements) reared in both L. esculentum leaves no phenolics were identified. α-Tomatine was the main glycoalkaloid in the host plant. The glycoalkaloid composition of the different S. littoralis materials was distinct, with α-tomatine and dehydrotomatine being the main detected compounds in larvae and excrements. These results add knowledge to the ecological interaction in this insect/plant duo, for which it is hard to obtain considerable sample amounts. Copyright © 2011 John Wiley & Sons, Ltd.