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Marc Lahaye - One of the best experts on this subject based on the ideXlab platform.
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determination of the chemical composition of Ulvan a cell wall polysaccharide from Ulva spp Ulvales chlorophyta by ft ir and chemometrics
Journal of Applied Phycology, 2009Co-Authors: Yannick Lerat, Annie Robic, Jeanfrancois Sassi, Dominique Bertrand, Marc LahayeAbstract:The water-soluble cell wall polysaccharides from green seaweeds of Ulva spp. (Ulvales, Chlorophyta), referred to as Ulvan, demonstrate composition- and structure-related functional properties. Mid-infrared spectroscopy combined with chemometric techniques was investigated as a means to rapidly predict the chemical composition of Ulvan extracts. A calibration was realized with 41 Ulvan extracts from two Ulva species. The variables studied included the constituent sugars (rhamnose, xylose, glucose, galactose, glucuronic acid, iduronic acid), protein, and sulfate contents. The correlation between Fourier transform infrared and chemical data was developed using partial least squares (PLS) regression with full cross-validation (leave one out). The coefficients of determination in cross-validation (\(R_{{\text{CAL}}}^2 \)) and the standard error in cross-validation were determined for each variable. The PLS model validation resulted in a coefficient of determination (\(R_{{\text{VAL}}}^2 \)) and a standard error in prediction. Good predictions were obtained for rhamnose (\(R_{{\text{VAL}}}^2 \) = 0.9244), xylose (\(R_{{\text{VAL}}}^2 \) = 0.8758), glucuronic acid (\(R_{{\text{VAL}}}^2 \) = 0.9415), and sulfate (\(R_{{\text{VAL}}}^2 \) = 0.9218), which are the main Ulvan constituents. However, minor components such as proteins, glucose, galactose, and iduronic acid were not correctly predicted. This study showed that mid-infrared spectroscopy combined with PLS regression is a reliable and fast method for the quantification of the main chemical constituents of Ulvan extracts.
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structure and interactions of Ulvan in the cell wall of the marine green algae Ulva rotundata Ulvales chlorophyceae
Carbohydrate Polymers, 2009Co-Authors: Annie Robic, Yannick Lerat, Jeanfrancois Sassi, Corinne Rondeaumouro, Marc LahayeAbstract:Abstract Ulvan, the sulfated cell-wall polysaccharides from green seaweeds ( Ulva species), presents structural and functional properties of interest for different applications. Its extraction yield in water varies depending on the species, the period of collect and the mode of conservation of algae. To identify limits of extraction, the structure and interactions of Ulvan in the cell wall of Ulva were investigated following a sequential solvent extraction. Hot sodium oxalate and hot dilute HCl were the two major extracts. Other solvents affecting protein structure or low hydrogen bonded polymers yielded minor Ulvan fractions but affected solid state 13 C NMR spectra indicating that proteins likely contributed to cross-link and/or to entrap Ulva cell wall polysaccharides. Ulvan-lyase degradation showed that Ulvan consisted in a wide continuum of related polysaccharides differing in the extent and type of fine structural characteristics. Besides solvent acidity, particle size of seaweeds was an important parameter controlling the Ulvan extraction efficiency. Major Ulvan cell wall interactions were discussed with regard to ionic interactions, covalent linkages and peculiar solution behavior of Ulvan in various physicochemical environments.
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Structure and interactions of Ulvan in the cell wall of the marine green algae Ulva rotundata (Ulvales, Chlorophyceae)
Carbohydrate Polymers, 2009Co-Authors: Annie Robic, Juliano Fernandes Sassi, Corinne Rondeau-mouro, Yannick Lerat, Marc LahayeAbstract:Ulvan, the sulfated cell-wall polysaccharides from green seaweeds (Ulva species), presents structural and functional properties of interest for different applications. Its extraction yield in water varies depending on the species, the period of collect and the mode of conservation of algae. To identify limits of extraction, the structure and interactions of Ulvan in the cell wall of Ulva were investigated following a sequential solvent extraction. Hot sodium oxalate and hot dilute HCl were the two major extracts. Other solvents affecting protein structure or low hydrogen bonded polymers yielded minor Ulvan fractions but affected solid state13C NMR spectra indicating that proteins likely contributed to cross-link and/or to entrap Ulva cell wall polysaccharides. Ulvan-lyase degradation showed that Ulvan consisted in a wide continuum of related polysaccharides differing in the extent and type of fine structural characteristics. Besides solvent acidity, particle size of seaweeds was an important parameter controlling the Ulvan extraction efficiency. Major Ulvan cell wall interactions were discussed with regard to ionic interactions, covalent linkages and peculiar solution behavior of Ulvan in various physicochemical environments. © 2009 Elsevier Ltd. All rights reserved.
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impact of stabilization treatments of the green seaweed Ulva rotundata chlorophyta on the extraction yield the physico chemical and rheological properties of Ulvan
Carbohydrate Polymers, 2008Co-Authors: Annie Robic, Jeanfrancois Sassi, Marc LahayeAbstract:Abstract The impact of freezing, freeze-drying, hot-air drying, brining and dry salting stabilization methods of Ulva rotundata has been studied on the yield, physico-chemical characteristics and rheological properties of Ulvan. Frozen (−30 and −80 °C) and freeze-dried algae yielded Ulvan extracts mainly composed of high molecular weight polysaccharides. These had the highest intrinsic viscosity and conservation modulus (G′) as copper/borate gels compared to Ulvan from fresh algae (taken as a reference) or Ulvan extracted from algae stabilized by other means. Cold stabilizations of algae yielded the lowest amounts of Ulvan. High Ulvan yields were obtained from Ulva air-dried at 50 and 70 °C but that at 50 °C was lower than that at 70 °C. Gelling properties and intrinsic viscosities from these Ulvans were better than that of fresh algae but lower than from cold treated seaweeds. Brining induced Ulvan degradation with poor rheological properties of the extracts compared to Ulvan from fresh algae. However, this process appears to ease extraction of polysaccharides. Compared to fresh algae, salted seaweeds stored at room temperature yielded degraded Ulvan. Decreasing the salting process temperature to 4 °C preserved Ulvan composition, structure and properties. However, Ulva salting hinders drastically Ulvan extraction. The different stabilization processes affected the chemical composition of Ulvan extracts and in particular, sulphate and protein contents. The results show that different stabilization conditions of Ulva biomass can be selected according to their cost-effectiveness and the required Ulvan chemical and macromolecular characteristics.
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Chemical composition and 13C NMR spectroscopic characterisation of Ulvans from Ulva (Ulvales, Chlorophyta)
Journal of Applied Phycology, 1999Co-Authors: Marc Lahaye, Enrique Alvarez-cabal Cimadevilla, Ralph Kuhlenkamp, Bernard Quemener, Vincent Lognoné, Patrick DionAbstract:The chemical composition and structures of several Ulvan extracts isolated from various Ulva species were studied. They were all composed mainly of rhamnose, glucuronic acid, xylose, glucose and sulphate with smaller amounts of iduronic acid and traces of galactose. Proteins were also present, most likely as contaminants. Precise quantification of the uronic acid content by chemical-enzymatic hydrolysis coupled to HPAEC-PAD analysis and by colorimetry was not achieved, most likely due to the incomplete hydrolysis of glucuronan segments, inadequate HPAEC-pulsed-amperometric response factor for iduronic acid and to a possible differential colorimetric response of the two uronic acids. ^13C NMR spectroscopic investigation of different Ulvans demonstrated that they were all based on Ulvanobiuronic acid 3-sulphate A and B repeating units [β-D-Glc pA-(1->4)-α-L-Rhap3S and α-L-IdopA-(1->4)-α-L-Rha p3S, respectively] as well as contiguous β 1->4 linked D-glucuronic acids possibly occurring either in Ulvan or as a separate glucuronan. Marked variations in the content of the repeating structures were seen among the different samples. However, due to the limited number of samples studied, no conclusion was reached concerning the effects of species and ecophysiological conditions on the chemistry of Ulvan.
Annie Robic - One of the best experts on this subject based on the ideXlab platform.
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determination of the chemical composition of Ulvan a cell wall polysaccharide from Ulva spp Ulvales chlorophyta by ft ir and chemometrics
Journal of Applied Phycology, 2009Co-Authors: Yannick Lerat, Annie Robic, Jeanfrancois Sassi, Dominique Bertrand, Marc LahayeAbstract:The water-soluble cell wall polysaccharides from green seaweeds of Ulva spp. (Ulvales, Chlorophyta), referred to as Ulvan, demonstrate composition- and structure-related functional properties. Mid-infrared spectroscopy combined with chemometric techniques was investigated as a means to rapidly predict the chemical composition of Ulvan extracts. A calibration was realized with 41 Ulvan extracts from two Ulva species. The variables studied included the constituent sugars (rhamnose, xylose, glucose, galactose, glucuronic acid, iduronic acid), protein, and sulfate contents. The correlation between Fourier transform infrared and chemical data was developed using partial least squares (PLS) regression with full cross-validation (leave one out). The coefficients of determination in cross-validation (\(R_{{\text{CAL}}}^2 \)) and the standard error in cross-validation were determined for each variable. The PLS model validation resulted in a coefficient of determination (\(R_{{\text{VAL}}}^2 \)) and a standard error in prediction. Good predictions were obtained for rhamnose (\(R_{{\text{VAL}}}^2 \) = 0.9244), xylose (\(R_{{\text{VAL}}}^2 \) = 0.8758), glucuronic acid (\(R_{{\text{VAL}}}^2 \) = 0.9415), and sulfate (\(R_{{\text{VAL}}}^2 \) = 0.9218), which are the main Ulvan constituents. However, minor components such as proteins, glucose, galactose, and iduronic acid were not correctly predicted. This study showed that mid-infrared spectroscopy combined with PLS regression is a reliable and fast method for the quantification of the main chemical constituents of Ulvan extracts.
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structure and interactions of Ulvan in the cell wall of the marine green algae Ulva rotundata Ulvales chlorophyceae
Carbohydrate Polymers, 2009Co-Authors: Annie Robic, Yannick Lerat, Jeanfrancois Sassi, Corinne Rondeaumouro, Marc LahayeAbstract:Abstract Ulvan, the sulfated cell-wall polysaccharides from green seaweeds ( Ulva species), presents structural and functional properties of interest for different applications. Its extraction yield in water varies depending on the species, the period of collect and the mode of conservation of algae. To identify limits of extraction, the structure and interactions of Ulvan in the cell wall of Ulva were investigated following a sequential solvent extraction. Hot sodium oxalate and hot dilute HCl were the two major extracts. Other solvents affecting protein structure or low hydrogen bonded polymers yielded minor Ulvan fractions but affected solid state 13 C NMR spectra indicating that proteins likely contributed to cross-link and/or to entrap Ulva cell wall polysaccharides. Ulvan-lyase degradation showed that Ulvan consisted in a wide continuum of related polysaccharides differing in the extent and type of fine structural characteristics. Besides solvent acidity, particle size of seaweeds was an important parameter controlling the Ulvan extraction efficiency. Major Ulvan cell wall interactions were discussed with regard to ionic interactions, covalent linkages and peculiar solution behavior of Ulvan in various physicochemical environments.
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Structure and interactions of Ulvan in the cell wall of the marine green algae Ulva rotundata (Ulvales, Chlorophyceae)
Carbohydrate Polymers, 2009Co-Authors: Annie Robic, Juliano Fernandes Sassi, Corinne Rondeau-mouro, Yannick Lerat, Marc LahayeAbstract:Ulvan, the sulfated cell-wall polysaccharides from green seaweeds (Ulva species), presents structural and functional properties of interest for different applications. Its extraction yield in water varies depending on the species, the period of collect and the mode of conservation of algae. To identify limits of extraction, the structure and interactions of Ulvan in the cell wall of Ulva were investigated following a sequential solvent extraction. Hot sodium oxalate and hot dilute HCl were the two major extracts. Other solvents affecting protein structure or low hydrogen bonded polymers yielded minor Ulvan fractions but affected solid state13C NMR spectra indicating that proteins likely contributed to cross-link and/or to entrap Ulva cell wall polysaccharides. Ulvan-lyase degradation showed that Ulvan consisted in a wide continuum of related polysaccharides differing in the extent and type of fine structural characteristics. Besides solvent acidity, particle size of seaweeds was an important parameter controlling the Ulvan extraction efficiency. Major Ulvan cell wall interactions were discussed with regard to ionic interactions, covalent linkages and peculiar solution behavior of Ulvan in various physicochemical environments. © 2009 Elsevier Ltd. All rights reserved.
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impact of stabilization treatments of the green seaweed Ulva rotundata chlorophyta on the extraction yield the physico chemical and rheological properties of Ulvan
Carbohydrate Polymers, 2008Co-Authors: Annie Robic, Jeanfrancois Sassi, Marc LahayeAbstract:Abstract The impact of freezing, freeze-drying, hot-air drying, brining and dry salting stabilization methods of Ulva rotundata has been studied on the yield, physico-chemical characteristics and rheological properties of Ulvan. Frozen (−30 and −80 °C) and freeze-dried algae yielded Ulvan extracts mainly composed of high molecular weight polysaccharides. These had the highest intrinsic viscosity and conservation modulus (G′) as copper/borate gels compared to Ulvan from fresh algae (taken as a reference) or Ulvan extracted from algae stabilized by other means. Cold stabilizations of algae yielded the lowest amounts of Ulvan. High Ulvan yields were obtained from Ulva air-dried at 50 and 70 °C but that at 50 °C was lower than that at 70 °C. Gelling properties and intrinsic viscosities from these Ulvans were better than that of fresh algae but lower than from cold treated seaweeds. Brining induced Ulvan degradation with poor rheological properties of the extracts compared to Ulvan from fresh algae. However, this process appears to ease extraction of polysaccharides. Compared to fresh algae, salted seaweeds stored at room temperature yielded degraded Ulvan. Decreasing the salting process temperature to 4 °C preserved Ulvan composition, structure and properties. However, Ulva salting hinders drastically Ulvan extraction. The different stabilization processes affected the chemical composition of Ulvan extracts and in particular, sulphate and protein contents. The results show that different stabilization conditions of Ulva biomass can be selected according to their cost-effectiveness and the required Ulvan chemical and macromolecular characteristics.
Masanori Hiraoka - One of the best experts on this subject based on the ideXlab platform.
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Crossing test among floating Ulva thalli forming ‘green tide’ in Japan
Hydrobiologia, 2020Co-Authors: Masanori Hiraoka, Masao Ohno, Shigeo Kawaguchi, Goro YoshidaAbstract:Crossing tests were made to determine the relationship between the identified Ulva pertusa, which commonly grows in Japan as an attached form on exposed rocks, and the floating Ulva forming “green tide” inside calm bays. The floating Ulva thalli were collected from five major green tide sites in Japan (Yokohama, Mikawa, Miyajima, Kochi and Hakata). Reproductive maturation was induced in U. pertusa and the floating thalli from each site. Mating between induced gametes was observed. It is therefore believed that the floating thalli from Yokohama, Mikawa and Miyajima were mainly U. pertusa, while those from Kochi and Hakata were of a different species (Ulva sp.l). Furthermore, the Ulva species found in Mikawa is also a species (Ulvasp.2) different from both U. pertusa and Ulva sp.l.
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microwave assisted hydrothermal extraction of sulfated polysaccharides from Ulva spp and monostroma latissimum
Food Chemistry, 2016Co-Authors: Shuntaro Tsubaki, Kiriyo Oono, Ayumu Onda, Masanori Hiraoka, Tomohiko MitaniAbstract:Abstract Microwave-assisted hydrothermal extraction was applied for production of sulfated polysaccharides from Ulva spp. and Monostroma latissimum . The maximum Ulvan yields attained 40.4 ± 3.2% ( Ulva meridionalis ) and 36.5 ± 3.1% ( Ulva ohnoi ) within 4 min of come-up time and 10 min of extraction time at 160 °C, respectively. The rhamnan sulfate yield from M . latissimum further attained 53.1 ± 7.2% at 140 °C. The sulfated polysaccharides were easily recovered from the extract by simple ethanol precipitation. In addition, molecular weights and viscosity of the extracted polysaccharides could be controlled by varying the extraction temperature. Dielectric measurement revealed that ionic conduction was the important parameter that affect the microwave susceptibility of algae-water mixture. The sulfated polysaccharides extracts are expected as potential feedstock for medical and food applications.
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Persistent occurrence of floating Ulva green tide in Hiroshima Bay, Japan: seasonal succession and growth patterns of Ulva pertusa and Ulva spp. (Chlorophyta, Ulvales)
Hydrobiologia, 2015Co-Authors: Goro Yoshida, Masayuki Uchimura, Masanori HiraokaAbstract:Since the late 1980’s, a persistent green tide of floating Ulva without any clear seasonal fluctuation has occurred in Hiroshima Bay, Seto Inland Sea, Japan. We hypothesized that the persistence is due to the co-existence of Ulva species with different seasonal growth patterns, and monitored the seasonal composition and growth characteristics of the constituent Ulva within the green tide. Two morphological types of Ulva were identified, and one type, U. pertusa , was almost the sole constituent during winter and spring. The other type Ulva spp., which has marginal microscopic serrations on the thallus, was dominant during summer and autumn. Both Ulva showed the highest relative growth rate in early autumn, but growth of Ulva spp. was faster in summer than that of U. pertusa and inhibited in winter. U. pertusa had more eurythermal characteristics in which the growth rate remained relatively high in winter. Water temperature was the most correlated environmental variable for the seasonal growth of both Ulva types rather than light or nutrients, but more influential on Ulva spp. Recent increasing trend of ambient seawater temperature is considered to be favorable for the growth of both Ulva types and a causative factor of the green tide.
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molecular phylogenetic analyses of the japanese Ulva and enteromorpha Ulvales ulvophyceae with special reference to the free floating Ulva
Phycological Research, 2003Co-Authors: Satoshi Shimada, Shinichi Nabata, Masafumi Iima, Masanori Hiraoka, Michio MasudaAbstract:SUMMARY In order to elucidate the species composition of freefloating Ulva that cause green tide in several bays in Japan, and to clarify the generic status of Ulva and Enteromorpha (Ulvales, Ulvophyceae), the nuclear encoded internal transcribed spacer (ITS) region including the 5.8S gene and the plastid encoded large subunit of ribulose-1, 5-bisphosphate carboxylase/ oxgenase ( rbc L) gene sequences for 15 species were determined. Both ITS and rbc L analyses indicate that free-floating Ulva samples are divided into four different lineages that correspond to Ulva lactuca Linnaeus, U. pertusa Kjellman, U. armoricana Dion et al . and U. fasciata Delile. These four species are distinguished by cell morphology including the arrangement of cells, the shape and size of cells and the position of chloroplasts. Molecular data also indicated that Ulva and Enteromorpha are not separated as respective monophyletic groups within a large monophyletic clade and congeneric as shown by previous molecular studies using the ITS sequences alone. This strongly suggests that these genera are congeneric and Enteromorpha should be reduced to the synonym of Ulva .
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Molecular phylogenetic analyses of the Japanese Ulva and Enteromorpha (Ulvales, Ulvophyceae), with special reference to the free‐floating Ulva
Phycological Research, 2003Co-Authors: Satoshi Shimada, Shinichi Nabata, Masafumi Iima, Masanori Hiraoka, Michio MasudaAbstract:SUMMARY In order to elucidate the species composition of freefloating Ulva that cause green tide in several bays in Japan, and to clarify the generic status of Ulva and Enteromorpha (Ulvales, Ulvophyceae), the nuclear encoded internal transcribed spacer (ITS) region including the 5.8S gene and the plastid encoded large subunit of ribulose-1, 5-bisphosphate carboxylase/ oxgenase ( rbc L) gene sequences for 15 species were determined. Both ITS and rbc L analyses indicate that free-floating Ulva samples are divided into four different lineages that correspond to Ulva lactuca Linnaeus, U. pertusa Kjellman, U. armoricana Dion et al . and U. fasciata Delile. These four species are distinguished by cell morphology including the arrangement of cells, the shape and size of cells and the position of chloroplasts. Molecular data also indicated that Ulva and Enteromorpha are not separated as respective monophyletic groups within a large monophyletic clade and congeneric as shown by previous molecular studies using the ITS sequences alone. This strongly suggests that these genera are congeneric and Enteromorpha should be reduced to the synonym of Ulva .
Zhien Li - One of the best experts on this subject based on the ideXlab platform.
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antioxidant activity of different sulfate content derivatives of polysaccharide extracted from Ulva pertusa chlorophyta in vitro
International Journal of Biological Macromolecules, 2005Co-Authors: Huimin Qi, Quanbin Zhang, Tingting Zhao, Rong Chen, Hong Zhang, Xizhen Niu, Zhien LiAbstract:Polysaccharide extracted from Ulva pertusa (Chlorophyta) is a group of sulfated heteropolysaccharide; for simplicity, the sulfated polysaccharide is referred to as Ulvan in this paper. In this study, different sulfate content Ulvans were prepared with sulfur trioxide/N,N-diinethylformamide (SO3-DMF) in formamide, and their antioxidant activities were investigated including scavenging activity of superoxide and hydroxyl radicals, reducing Power and metal chelating ability. As expected, we obtained several satisfying results, as follows: firstly, high sulfate content Ulvans had more effective scavenging activity on hydroxyl radical than natural Ulvan. Secondly, comparing with natural Ulvan, high sulfate content Ulvans exhibited stronger reducing power. Thirdly, HU4 (sulfate content, 30.8%) and HU5 (sulfate content, 32.8%) showed more pronounce chelating ability on ferrous ion at high concentration than other samples. (c) 2005 Elsevier B.V. All rights reserved.
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antioxidant activity of different molecular weight sulfated polysaccharides from Ulva pertusa kjellm chlorophyta
Journal of Applied Phycology, 2005Co-Authors: Huimin Qi, Quanbin Zhang, Tingting Zhao, Zhien Li, Zengqin Zhao, Ronge XingAbstract:Polysaccharides extracted from Ulva pertusa Kjellm (Chlorophyta) are a group of sulfated heteropolysaccharides, the Ulvans. In this study, different molecular weight Ulvans were prepared by H2O2 degradation and their antioxidant activities investigated including superoxide and hydroxyl radical scavenging activity, reducing power and metal chelating ability. The molecular weights of natural and degraded Ulvans were 151.7, 64.5, 58.0, and 28.2 kDa, respectively, as determined by high performance gel permeation chromatography. Among the four samples, U3 (the lowest molecular weight sample) showed significant inhibitory effects on superoxide and hydroxyl radicals with IC50 values of 22.1 μ g mL−1 and 2.8 mg mL−1; its reducing power and metal chelating ability were also the strongest among the four samples. All the other samples also demonstrated strong activity against superoxide radicals. The results indicated that molecular weight had a significant effect on the antioxidant activity of Ulvan with low molecular weight Ulvan having stronger antioxidant activity.
Huimin Qi - One of the best experts on this subject based on the ideXlab platform.
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antioxidant activity of different sulfate content derivatives of polysaccharide extracted from Ulva pertusa chlorophyta in vitro
International Journal of Biological Macromolecules, 2005Co-Authors: Huimin Qi, Quanbin Zhang, Tingting Zhao, Rong Chen, Hong Zhang, Xizhen Niu, Zhien LiAbstract:Polysaccharide extracted from Ulva pertusa (Chlorophyta) is a group of sulfated heteropolysaccharide; for simplicity, the sulfated polysaccharide is referred to as Ulvan in this paper. In this study, different sulfate content Ulvans were prepared with sulfur trioxide/N,N-diinethylformamide (SO3-DMF) in formamide, and their antioxidant activities were investigated including scavenging activity of superoxide and hydroxyl radicals, reducing Power and metal chelating ability. As expected, we obtained several satisfying results, as follows: firstly, high sulfate content Ulvans had more effective scavenging activity on hydroxyl radical than natural Ulvan. Secondly, comparing with natural Ulvan, high sulfate content Ulvans exhibited stronger reducing power. Thirdly, HU4 (sulfate content, 30.8%) and HU5 (sulfate content, 32.8%) showed more pronounce chelating ability on ferrous ion at high concentration than other samples. (c) 2005 Elsevier B.V. All rights reserved.
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antioxidant activity of different molecular weight sulfated polysaccharides from Ulva pertusa kjellm chlorophyta
Journal of Applied Phycology, 2005Co-Authors: Huimin Qi, Quanbin Zhang, Tingting Zhao, Zhien Li, Zengqin Zhao, Ronge XingAbstract:Polysaccharides extracted from Ulva pertusa Kjellm (Chlorophyta) are a group of sulfated heteropolysaccharides, the Ulvans. In this study, different molecular weight Ulvans were prepared by H2O2 degradation and their antioxidant activities investigated including superoxide and hydroxyl radical scavenging activity, reducing power and metal chelating ability. The molecular weights of natural and degraded Ulvans were 151.7, 64.5, 58.0, and 28.2 kDa, respectively, as determined by high performance gel permeation chromatography. Among the four samples, U3 (the lowest molecular weight sample) showed significant inhibitory effects on superoxide and hydroxyl radicals with IC50 values of 22.1 μ g mL−1 and 2.8 mg mL−1; its reducing power and metal chelating ability were also the strongest among the four samples. All the other samples also demonstrated strong activity against superoxide radicals. The results indicated that molecular weight had a significant effect on the antioxidant activity of Ulvan with low molecular weight Ulvan having stronger antioxidant activity.
