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Pilar Ruperez - One of the best experts on this subject based on the ideXlab platform.

  • bioactivity of sulfated polysaccharides from the edible red seaweed Mastocarpus stellatus
    Bioactive Carbohydrates and Dietary Fibre, 2014
    Co-Authors: Eva Gomezordonez, Antonio Jimenezescrig, Pilar Ruperez
    Abstract:

    Abstract Carrageenans are typical sulfated-galactans from red seaweeds. Their main biological properties as antioxidants and anticoagulants were studied in vitro in Mastocarpus stellatus . On sequential extraction with cold-water (F1), hot-water (F2), acid (F3) and alkali (F4), four soluble polysaccharide fractions plus an insoluble cellulose residue (F5) were obtained. Composition was assessed by gas–liquid chromatography, ion chromatography and Fourier Transform Infrared (FTIR-ATR) spectroscopy. Multifunctional antioxidant capacity was assayed by FRAP- reducing power, ABTS- and photochemiluminiscence (PCL)- radical scavenging methods. Heparin-like anticoagulant capacity was studied by intrinsic-APTT and extrinsic-PT pathways. Recovery of F1–F4 yielded almost 60%, which main components were: neutral sugar (21.2–34.7 g/100 g), sulfate (0.6–3.9 g/100 g), protein (0.1–3.4 g/100 g) and uronic acid (0.9–2.7 g/100 g). Galactose (70.2–95.2 mol/100 g) was the predominant sugar in F1–F4 and sulfate their main inorganic anion (75–80% of total). F1–F3 contained the bulk of carrageenans. Degree of sulfation ranged from 0.22 (F1) to 0.03 (F3), respectively. Typical absorption bands of kappa-/iota-carrageenans at 930, 845 and 805 cm −1 assigned respectively to 3,6-anhydro-galactose, galactose-4-sulfate and 3,6-anhydro-galactose-2-sulfate appeared in FTIR spectra. Upon extraction with acid and alkali polymerization degree decreased significantly meanwhile iota- versus kappa-carrageenan increased. The highest FRAP-reducing power (44.9 μmol Trolox equivalents/g) and ABTS-radical scavenging ability was shown for cold-water soluble F1. Regarding anti-coagulant capacity, again F1 showed the best values (28 mg heparin equivalents/g), suggesting that its higher sulfate content associated to its high MW might exert a positive effect. Sulfate played a determinant role as antioxidant and anticoagulant, but a high MW was also relevant for the anticoagulant capacity of M. stellatus carrageenans.

  • Brown and red seaweeds as potential sources of antioxidant nutraceuticals
    Journal of Applied Phycology, 2012
    Co-Authors: Antonio Jiménez-escrig, Eva Gómez-ordóñez, Pilar Ruperez
    Abstract:

    Multifunctional antioxidant potential of several brown and red edible seaweeds was evaluated in organic and aqueous soluble extracts. The great reduction power and radical scavenging activity of Bifurcaria bifurcata —a Sargassaceae brown algal species—in both organic and aqueous extracts were emphasized. In addition, two Gigartinaceae red algal species, Gigartina pistillata and Mastocarpus stellatus showed relatively high reduction power in the aqueous extracts. When all of the variables of the aqueous extracts were combined in a principal component analysis, a clear differentiation pattern among the tested seaweeds was observed. In the Phaeophyceae, the correlation found among reduction power, radical scavenging activity and total phenolic content is in favour of the involvement of phenolic compounds in the antioxidant mechanisms, whereas in the case of the Florideophyceae, the role of sulphate-containing polysaccharides in reduction power is presumably shown. Nevertheless, the evidence of some taxonomy-based clustering (class and order levels) in this study may prove that polyphenol and sulphate content, besides multifunctional antioxidant profile, are related to specific groups of seaweeds. This evidence could help the search of suitable sources of phytochemicals from seaweeds for further nutraceutical applications.

  • molecular weight distribution of polysaccharides from edible seaweeds by high performance size exclusion chromatography hpsec
    Talanta, 2012
    Co-Authors: Eva Gomezordonez, Antonio Jimenezescrig, Pilar Ruperez
    Abstract:

    Biological properties of polysaccharides from seaweeds are related to their composition and structure. Many factors such as the kind of sugar, type of linkage or sulfate content of algal biopolymers exert an influence in the relationship between structure and function. Besides, the molecular weight (MW) also plays an important role. Thus, a simple, reliable and fast HPSEC method with refractive index detection was developed and optimized for the MW estimation of soluble algal polysaccharides. Chromatogram shape and repeatability of retention time was considerably improved when sodium nitrate was used instead of ultrapure water as mobile phase. Pullulan and dextran standards of different MW were used for method calibration and validation. Also, main polysaccharide standards from brown (alginate, fucoidan, laminaran) and red seaweeds (kappa- and iota-carrageenan) were used for quantification and method precision and accuracy. Relative standard deviation (RSD) of repeatability for retention time, peak areas and inter-day precision was below 0.7%, 2.5% and 2.6%, respectively, which indicated good repeatability and precision. Recoveries (96.3-109.8%) also showed its fairly good accuracy. Regarding linearity, main polysaccharide standards from brown or red seaweeds showed a highly satisfactory correlation coefficient (r>0.999). Moreover, a good sensitivity was shown, with corresponding limits of detection and quantitation in mg/mL of 0.05-0.21 and 0.16-0.31, respectively. The method was applied to the MW estimation of standard algal polysaccharides, as well as to the soluble polysaccharide fractions from the brown seaweed Saccharina latissima and the red Mastocarpus stellatus, respectively. Although distribution of molecular weight was broad, the good repeatability for retention time provided a good precision in MW estimation of polysaccharides. Water- and alkali-soluble fractions from S. latissima ranged from very high (>2400 kDa) to low MW compounds ( 1400 kDa to <10 kDa), related to the different solubility of carrageenans in red seaweeds. In summary, the method developed allows for the molecular weight analysis of seaweed polysaccharides with very good precision, accuracy, linearity and sensitivity within a short time.

  • ftir atr spectroscopy as a tool for polysaccharide identification in edible brown and red seaweeds
    Food Hydrocolloids, 2011
    Co-Authors: Eva Gomezordonez, Pilar Ruperez
    Abstract:

    Abstract Phycocolloids present in three brown ( Himanthalia elongata , Bifurcaria bifurcata , Saccharina latissima ) and five red edible seaweeds ( Mastocarpus stellatus , Gigartina pistillata , Chondracanthus acicularis , Nemalion helminthoides and Dumontia contorta ) were studied by FTIR-ATR spectroscopy. Infrared spectra of polysaccharide standards (alginate, agar, iota-, kappa- and lambda-carrageenan) were obtained for comparison. The main polysaccharide found in brown seaweeds was alginate, a linear copolymer of mannuronic (M) and guluronic acid (G). Alginate M/G ratio was tentatively estimated from specific absorption bands (808/787 cm −1 and 1030/1080 cm −1 ) in infrared spectra, suggesting higher values of mannuronic than guluronic acid blocks (M/G > 1) for brown seaweeds. According to their infrared spectra, all the red seaweeds studied were mainly carrageenan producers. Thus, M. stellatus showed absorption bands at 929.0, 844.7 and 803.2 cm −1 of a typical hybrid kappa/iota/mu/nu-carrageenan, meanwhile G. pistillata and C. acicularis , showed the characteristic broad band (830–820 cm −1 ) of lambda-type carrageenan. Moreover, when the second-derivative was obtained to improve resolution of overlapped bands in the original FTIR spectra, this band was divided into several sharper signals, indicating the presence of lambda-/theta-/xi-carrageenans. Accordingly with their FTIR spectra, N. helminthoides contained sulphated polysaccharides, such as carrageenan or mannans, while D. contorta produced lambda- with lesser amounts of kappa-carrageenan. Therefore, FTIR-ATR spectroscopy is proposed as a useful tool for the food, pharmaceutical and cosmetics industry to check the phycocolloid quality of a raw seaweed material by a quick and non-destructive method.

  • dietary fibre and physicochemical properties of several edible seaweeds from the northwestern spanish coast
    Food Research International, 2010
    Co-Authors: Eva Gomezordonez, Antonio Jimenezescrig, Pilar Ruperez
    Abstract:

    Abstract Proximate composition (moisture, ash, protein and oil content), total dietary fibre content and physicochemical properties of three brown and two red edible Spanish seaweeds, namely: Himanthalia elongata (sea spaghetti), Bifurcaria bifurcata , Laminaria saccharina (sweet kombu), Mastocarpus stellatus and Gigartina pistillata were studied. Ashes (24.9–36.4%) were high in all samples. Protein content ranged from 10.9 to 25.7%, being much higher for Laminaria (25.7%) followed by the red seaweeds (15.5–21.3%). Minor components were lipids (0.3–0.9%) in all samples except for Bifurcaria (5.6%). Total dietary fibre content ranged from 29.3 to 37.4% of which 39.1–74.7% was soluble. For brown algae, the soluble fibre contained uronic acids from alginates and neutral sugars from sulphated fucoidan and laminarin. For red seaweeds, the main neutral sugars corresponded to sulphated galactans (carrageenan or agar). Insoluble fibres (7.4–22.7%) were essentially made of cellulose with an important contribution of Klason lignin especially in brown seaweeds (9.5–10.8%). Regarding the main physicochemical properties, swelling and water retention capacity were high in all samples, while oil retention was low, related to the hydrophilic nature of fibre polysaccharides. In conclusion, these seaweeds can be estimated as a good source of food fibre, protein and minerals for human consumption.

L Hilliou - One of the best experts on this subject based on the ideXlab platform.

  • tailoring kappa iota hybrid carrageenan from Mastocarpus stellatus with desired gel quality through pre extraction alkali treatment
    Food Hydrocolloids, 2013
    Co-Authors: Gabriela Azevedo, L Hilliou, Gabriel Bernardo, Isabel Sousapinto, Ralph W Adams, Mathias Nilsson, Ronald D Villanueva
    Abstract:

    Mastocarpus stellatus seaweeds were subjected to different alkali pre-treatments to investigate the effect of alkali type, concentration and treatment duration on the chemical structure and the gelling properties of extracted kappa/iota-hybrid carrageenan (KI). Increasing the concentration in KOH and the pretreatment time gives KI with lower amounts of nu-carrageenan units, which have a direct impact on the improved gelling properties. However, excessive KOH concentration and pre-treatment duration give KI with smaller molecular mass and depressed gel properties. NaOH is more efficient in converting nucarrageenan to iota-carrageenan, but no correlation between the chemical structure and gel properties was found. An interaction between the alkali concentration and the pre-treatment duration complicates the rationalization of NaOH efficiency. A set of KI with 60-75 mol% kappa-carrageenan and tailored gelling properties for a wide range of applications is delivered. (C) 2012 Elsevier Ltd. All rights reserved.

  • the impact of seaweed life phase and postharvest storage duration on the chemical and rheological properties of hybrid carrageenans isolated from portuguese Mastocarpus stellatus
    Carbohydrate Polymers, 2012
    Co-Authors: Fabio D.s. Larotonda, L Hilliou, Pedro M Abreu, Maria H Abreu, A M Sereno, M P Goncalves
    Abstract:

    Abstract Variations in chemical and gelling characteristics of hybrid carrageenan extracted from Mastocarpus stellatus seaweeds are studied in order to explore potential links between the seaweeds life phase, the seaweeds postharvest storage duration and the phycocolloids properties. Chemical structures of phycocolloids were assessed by Fourier Transform Infrared spectroscopy (FTIR) and 1 H NMR spectroscopy. Rheological properties of hybrid carrageenans, such as intrinsic viscosity ([ η ]), gel elasticity ( G 0 ), gel setting temperature ( T g ) and gel melting temperature ( T m ), were measured with a stress rheometer. Seasonal variation in the degree of sulphates of native extracts and in their corresponding gelling properties is found. The minimum in gelling properties coincides with a minimum of fructified gametophytes in populations harvested during the cold season. Alkali treated extracts also show minimum gelling properties during the cold season but no correlation with variations in the chemical characteristics could be identified. The gel setting temperature is the only significant change in the properties of hybrid carrageenans extracted from dried seaweeds stored over 39 months in opaque and sealed plastic bags. These results point to non trivial relationships between the life stages of M. stellatus seaweeds, the chemical structure and gel properties of the alkali-extracted phycocolloids, and suggest a route towards the sustainable exploitation of the natural resource.

  • effect of extraction parameters on the chemical structure and gel properties of κ ι hybrid carrageenans obtained from Mastocarpus stellatus
    Biomolecular Engineering, 2006
    Co-Authors: L Hilliou, Fabio D.s. Larotonda, Alberto M. Sereno, Pedro M Abreu, A M Ramos, M P Goncalves
    Abstract:

    Extraction parameters (temperature, pH, duration) and alkaline pre-treatment duration have been systematically varied in the aim of exploring their impact on both chemical structure and gelling properties of carrageenan biopolymers obtained from Mastocarpus stellatus seaweeds, collected on the Northern coast of Portugal. Increasing the alkaline pre-treatment duration PT leads to κ/ι-hybrid carrageenans containing less sulphate groups and biological precursor monomers. As a result, gel properties in the presence of KCl are improved as demonstrated by the increase in the Young's modulus with parameter PT. Increasing the extraction duration t ameliorates the biopolymer yield with no significant change in the complex κ/ι-hybrid carrageenan chemical structure. However, smaller molecular weights are obtained and gel properties are seen to be negatively affected. Extraction temperature and pH have dramatic effects on the biopolymer gel strength, and a set of extraction parameters optimized with respect to extraction yield and gel properties is reported. In addition, κ/ι-hybrid carrageenans obtained throughout this study exhibit a wide range of gel strengths in KCl, and allow us to present correlations between gel thermal properties and the κ/ι-hybrid carrageenans chemical structure.

Eva Gomezordonez - One of the best experts on this subject based on the ideXlab platform.

  • bioactivity of sulfated polysaccharides from the edible red seaweed Mastocarpus stellatus
    Bioactive Carbohydrates and Dietary Fibre, 2014
    Co-Authors: Eva Gomezordonez, Antonio Jimenezescrig, Pilar Ruperez
    Abstract:

    Abstract Carrageenans are typical sulfated-galactans from red seaweeds. Their main biological properties as antioxidants and anticoagulants were studied in vitro in Mastocarpus stellatus . On sequential extraction with cold-water (F1), hot-water (F2), acid (F3) and alkali (F4), four soluble polysaccharide fractions plus an insoluble cellulose residue (F5) were obtained. Composition was assessed by gas–liquid chromatography, ion chromatography and Fourier Transform Infrared (FTIR-ATR) spectroscopy. Multifunctional antioxidant capacity was assayed by FRAP- reducing power, ABTS- and photochemiluminiscence (PCL)- radical scavenging methods. Heparin-like anticoagulant capacity was studied by intrinsic-APTT and extrinsic-PT pathways. Recovery of F1–F4 yielded almost 60%, which main components were: neutral sugar (21.2–34.7 g/100 g), sulfate (0.6–3.9 g/100 g), protein (0.1–3.4 g/100 g) and uronic acid (0.9–2.7 g/100 g). Galactose (70.2–95.2 mol/100 g) was the predominant sugar in F1–F4 and sulfate their main inorganic anion (75–80% of total). F1–F3 contained the bulk of carrageenans. Degree of sulfation ranged from 0.22 (F1) to 0.03 (F3), respectively. Typical absorption bands of kappa-/iota-carrageenans at 930, 845 and 805 cm −1 assigned respectively to 3,6-anhydro-galactose, galactose-4-sulfate and 3,6-anhydro-galactose-2-sulfate appeared in FTIR spectra. Upon extraction with acid and alkali polymerization degree decreased significantly meanwhile iota- versus kappa-carrageenan increased. The highest FRAP-reducing power (44.9 μmol Trolox equivalents/g) and ABTS-radical scavenging ability was shown for cold-water soluble F1. Regarding anti-coagulant capacity, again F1 showed the best values (28 mg heparin equivalents/g), suggesting that its higher sulfate content associated to its high MW might exert a positive effect. Sulfate played a determinant role as antioxidant and anticoagulant, but a high MW was also relevant for the anticoagulant capacity of M. stellatus carrageenans.

  • molecular weight distribution of polysaccharides from edible seaweeds by high performance size exclusion chromatography hpsec
    Talanta, 2012
    Co-Authors: Eva Gomezordonez, Antonio Jimenezescrig, Pilar Ruperez
    Abstract:

    Biological properties of polysaccharides from seaweeds are related to their composition and structure. Many factors such as the kind of sugar, type of linkage or sulfate content of algal biopolymers exert an influence in the relationship between structure and function. Besides, the molecular weight (MW) also plays an important role. Thus, a simple, reliable and fast HPSEC method with refractive index detection was developed and optimized for the MW estimation of soluble algal polysaccharides. Chromatogram shape and repeatability of retention time was considerably improved when sodium nitrate was used instead of ultrapure water as mobile phase. Pullulan and dextran standards of different MW were used for method calibration and validation. Also, main polysaccharide standards from brown (alginate, fucoidan, laminaran) and red seaweeds (kappa- and iota-carrageenan) were used for quantification and method precision and accuracy. Relative standard deviation (RSD) of repeatability for retention time, peak areas and inter-day precision was below 0.7%, 2.5% and 2.6%, respectively, which indicated good repeatability and precision. Recoveries (96.3-109.8%) also showed its fairly good accuracy. Regarding linearity, main polysaccharide standards from brown or red seaweeds showed a highly satisfactory correlation coefficient (r>0.999). Moreover, a good sensitivity was shown, with corresponding limits of detection and quantitation in mg/mL of 0.05-0.21 and 0.16-0.31, respectively. The method was applied to the MW estimation of standard algal polysaccharides, as well as to the soluble polysaccharide fractions from the brown seaweed Saccharina latissima and the red Mastocarpus stellatus, respectively. Although distribution of molecular weight was broad, the good repeatability for retention time provided a good precision in MW estimation of polysaccharides. Water- and alkali-soluble fractions from S. latissima ranged from very high (>2400 kDa) to low MW compounds ( 1400 kDa to <10 kDa), related to the different solubility of carrageenans in red seaweeds. In summary, the method developed allows for the molecular weight analysis of seaweed polysaccharides with very good precision, accuracy, linearity and sensitivity within a short time.

  • ftir atr spectroscopy as a tool for polysaccharide identification in edible brown and red seaweeds
    Food Hydrocolloids, 2011
    Co-Authors: Eva Gomezordonez, Pilar Ruperez
    Abstract:

    Abstract Phycocolloids present in three brown ( Himanthalia elongata , Bifurcaria bifurcata , Saccharina latissima ) and five red edible seaweeds ( Mastocarpus stellatus , Gigartina pistillata , Chondracanthus acicularis , Nemalion helminthoides and Dumontia contorta ) were studied by FTIR-ATR spectroscopy. Infrared spectra of polysaccharide standards (alginate, agar, iota-, kappa- and lambda-carrageenan) were obtained for comparison. The main polysaccharide found in brown seaweeds was alginate, a linear copolymer of mannuronic (M) and guluronic acid (G). Alginate M/G ratio was tentatively estimated from specific absorption bands (808/787 cm −1 and 1030/1080 cm −1 ) in infrared spectra, suggesting higher values of mannuronic than guluronic acid blocks (M/G > 1) for brown seaweeds. According to their infrared spectra, all the red seaweeds studied were mainly carrageenan producers. Thus, M. stellatus showed absorption bands at 929.0, 844.7 and 803.2 cm −1 of a typical hybrid kappa/iota/mu/nu-carrageenan, meanwhile G. pistillata and C. acicularis , showed the characteristic broad band (830–820 cm −1 ) of lambda-type carrageenan. Moreover, when the second-derivative was obtained to improve resolution of overlapped bands in the original FTIR spectra, this band was divided into several sharper signals, indicating the presence of lambda-/theta-/xi-carrageenans. Accordingly with their FTIR spectra, N. helminthoides contained sulphated polysaccharides, such as carrageenan or mannans, while D. contorta produced lambda- with lesser amounts of kappa-carrageenan. Therefore, FTIR-ATR spectroscopy is proposed as a useful tool for the food, pharmaceutical and cosmetics industry to check the phycocolloid quality of a raw seaweed material by a quick and non-destructive method.

  • dietary fibre and physicochemical properties of several edible seaweeds from the northwestern spanish coast
    Food Research International, 2010
    Co-Authors: Eva Gomezordonez, Antonio Jimenezescrig, Pilar Ruperez
    Abstract:

    Abstract Proximate composition (moisture, ash, protein and oil content), total dietary fibre content and physicochemical properties of three brown and two red edible Spanish seaweeds, namely: Himanthalia elongata (sea spaghetti), Bifurcaria bifurcata , Laminaria saccharina (sweet kombu), Mastocarpus stellatus and Gigartina pistillata were studied. Ashes (24.9–36.4%) were high in all samples. Protein content ranged from 10.9 to 25.7%, being much higher for Laminaria (25.7%) followed by the red seaweeds (15.5–21.3%). Minor components were lipids (0.3–0.9%) in all samples except for Bifurcaria (5.6%). Total dietary fibre content ranged from 29.3 to 37.4% of which 39.1–74.7% was soluble. For brown algae, the soluble fibre contained uronic acids from alginates and neutral sugars from sulphated fucoidan and laminarin. For red seaweeds, the main neutral sugars corresponded to sulphated galactans (carrageenan or agar). Insoluble fibres (7.4–22.7%) were essentially made of cellulose with an important contribution of Klason lignin especially in brown seaweeds (9.5–10.8%). Regarding the main physicochemical properties, swelling and water retention capacity were high in all samples, while oil retention was low, related to the hydrophilic nature of fibre polysaccharides. In conclusion, these seaweeds can be estimated as a good source of food fibre, protein and minerals for human consumption.

Malcolm J Shick - One of the best experts on this subject based on the ideXlab platform.

  • ultraviolet radiation absorbing mycosporine like amino acids maas are acquired from their diet by medaka fish oryzias latipes but not by skh 1 hairless mice
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1998
    Co-Authors: Donald S Mason, Malcolm J Shick, Freya Schafer, Walter C Dunlap
    Abstract:

    To assess whether vertebrates can acquire, from their diet, ultraviolet radiation-absorbing mycosporine-like amino acids (MAAs), medaka fish and hairless mice were maintained for 150 and 130 days, respectively, on diets either including Mastocarpus stellatus (rich in MAAs) or the same diets without this red alga. In medaka, the MAAs palythine and asterina-330, present in trace quantities in the diet with added M. stellatus, were present in significantly greater quantities in the eyes of fish fed this diet than in the eyes of control fish. Only traces of MAAs were present in the skin of medaka fed the diet containing MAAs. Shinorine, the principal MAA in M. stellatus, was not found in any tissues of medaka, which raises questions about the specificity of transport of MAAs. In hairless mice, no dietary MAAs were found in the tissues of the eyes, skin, or liver after maintenance on the experimental diet. Low concentrations of shinorine were present only in the tissues of the small and large intestines. These results indicate that MAAs are acquired from their diet and translocated to superficial tissues by teleost fish, but that mammals may be incapable of such. Thus, dietary supplementation with MAAs may be useful in aquacultured species of fish, but MAAs as 'dietary sunscreens' may not be an option for mammals, including humans. Nevertheless, our demonstration of the uptake of shinorine by human skin cancer cells in culture raises evolutionary questions regarding the organ specificity of the capacity for the cellular transport of MAAs.

  • mycosporine like amino acids provide protection against ultraviolet radiation in eggs of the green sea urchin strongylocentrotus droebachiensis
    Photochemistry and Photobiology, 1996
    Co-Authors: Nikki L Adams, Malcolm J Shick
    Abstract:

    A photoprotective role of ultraviolet radiation-absorbing mycosporine-like amino acids (MAAs) in eggs of the green sea urchin Strongylocentrotus droebachiensis was demonstrated by comparing UV-induced delays in the first division of embryos having either high or low concentrations of MAAs. Embryos from adult urchins fed Laminaria saccharina (no MAAs) had low concentrations of MAAs and experienced a significantly longer UV-induced delay in cleavage (25.1%) than MAA-rich embryos from adults fed Mastocarpus stellatus (12.8% delay) or a combination diet of both macroalgae (12.3% delay). Collectively, these embryos displayed a significant inverse logarithmic relationship between MAA concentration and percentage cleavage delay, so that the greater the MAA concentration in the eggs, the less they were affected by UV radiation. This is the first study to examine such MAA manipulation of cellular MAA concentrations with no prior UV exposure of the experimental subjects. Concentrations of MAAs were also measured in unfertilized eggs, blastulae, gastrulae and early pluteus larvae, providing the first documentation of changes in MAAs during embryological and larval development. The concentration of shinorine (the principal MAA in the eggs) did not change during short-term UV exposure in vivo or long-term exposure in vitro; such photostability is a useful attribute of a natural sunscreen.

Manuel Sastre E De Vicente - One of the best experts on this subject based on the ideXlab platform.

  • a physicochemical study of al 3 interactions with edible seaweed biomass in acidic waters
    Journal of Food Science, 2012
    Co-Authors: Pablo Lodeiro, Marta Lopezgarcia, Luz Herrero, Javier Cremades, Ignacio Bárbara, Roberto Herrero, José L. Barriada, Manuel Sastre E De Vicente
    Abstract:

    In this article, a study of the Al(+3) interactions in acidic waters with biomass of different edible seaweeds: brown (Fucus vesiculosus, Saccorhiza polyschides), red (Mastocarpus stellatus, Gelidium sesquipedale, Chondrus crispus), and green (Ulva rigida, Codium tomentosum), has been performed. The influence of both, the initial concentration of metal and the solution pH, on the Al-uptake capacity of the biomass has been analyzed. From preliminary tests, species Fucus vesiculosus and Gelidium sesquipedale have been selected for a more exhaustive analysis. Sorption kinetic studies demonstrated that 60 min are enough to reach equilibrium. The intraparticle diffusion model has been used to describe kinetic data. Equilibrium studies have been carried out at pH values of 1, 2.5, and 4. Langmuir isotherms showed that the best uptake values, obtained at pH 4, were 33 mg/g for F. vesiculosus and 9.2 mg/g for G. sesquipedale. These edible seaweeds have been found particularly effective in binding aluminum metal ions for most of the conditions tested. Physicochemical data reported at these low pH values could be of interest, not only in modeling aluminum-containing antacids-food pharmacokinetic processes produced in the stomach (pH values 1 to 3) but in remediation studies in acidic waters.

  • a physicochemical study of al 3 interactions with edible seaweed biomass in acidic waters
    Journal of Food Science, 2012
    Co-Authors: Pablo Lodeiro, Marta Lopezgarcia, Luz Herrero, Javier Cremades, Ignacio Bárbara, Roberto Herrero, José L. Barriada, Manuel Sastre E De Vicente
    Abstract:

    In this article, a study of the Al(+3) interactions in acidic waters with biomass of different edible seaweeds: brown (Fucus vesiculosus, Saccorhiza polyschides), red (Mastocarpus stellatus, Gelidium sesquipedale, Chondrus crispus), and green (Ulva rigida, Codium tomentosum), has been performed. The influence of both, the initial concentration of metal and the solution pH, on the Al-uptake capacity of the biomass has been analyzed. From preliminary tests, species Fucus vesiculosus and Gelidium sesquipedale have been selected for a more exhaustive analysis. Sorption kinetic studies demonstrated that 60 min are enough to reach equilibrium. The intraparticle diffusion model has been used to describe kinetic data. Equilibrium studies have been carried out at pH values of 1, 2.5, and 4. Langmuir isotherms showed that the best uptake values, obtained at pH 4, were 33 mg/g for F. vesiculosus and 9.2 mg/g for G. sesquipedale. These edible seaweeds have been found particularly effective in binding aluminum metal ions for most of the conditions tested. Physicochemical data reported at these low pH values could be of interest, not only in modeling aluminum-containing antacids-food pharmacokinetic processes produced in the stomach (pH values 1 to 3) but in remediation studies in acidic waters.

  • the efficiency of the red alga Mastocarpus stellatus for remediation of cadmium pollution
    Bioresource Technology, 2008
    Co-Authors: Roberto Herrero, Raquel Rojo, Pablo Lodeiro, Pilar Rodríguez, Andrea Ciorba, Manuel Sastre E De Vicente
    Abstract:

    Abstract This work reports the results of the study for cadmium binding by the dead red macroalga Mastocarpus stellatus . Kinetics sorption experiments demonstrated the high rate of metal biosorption: the system attained over 50% of the total biomass cadmium uptake within 2 min of contact and over 90% in the first 9 min. The kinetic data were successfully described by a pseudo-second order model with rate constants ranging from 1.06 to 10 g mmol −1  min −1 , as a function of initial metal concentration and temperature. The equilibrium binding was accurately represented in terms of Langmuir and Langmuir–Freundlich models. The sorption isotherms at constant pH showed uptake values as 0.49 mmol g −1 (at pH 2.4), 0.56 mmol g −1 (at pH 4) and 0.59 mmol g −1 (at pH 6), while the affinity constant values were between 0.6 and 5 mmol −1  L (Langmuir fit). The acid–base properties of the alga were also studied, obtaining the total number of acid groups, 2.5 mmol g −1 , and their apparent p K value, 1.56, using the Katchalsky model. Desorption studies were conducted employing different HNO 3 concentrations and desorption times.