Mehdi Tabarsa
Tarbiat Modares University, Department of Seafood Processing, Faculty Member
- Structural Analyses of Polysaccharides (GC-MS & NMR Spectroscopy), Biological Activity Screening (Immunomodulatory and Anti-cancer), Extraction and Purification of Bio-active Sulfated Polysaccharides, Functional Foods Research, Gene expression, Structural Analysis, and 10 morePersian Gulf, Seaweed, Immunomodulation, Extraction and Purification of Bio-active Sulfated Poylsaccharides, Anti-cancer, Amino Acid Profile, Sulfated polysaccharide, Brown Seaweed, Padina pavonica, and Mineral contentedit
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The effect of extraction methods using water, acid, Alcalase and Cellulase was studied on structure-bioactivity relationship of alginates from Colpomenia peregrina. Enzyme-assisted extractions produced alginates with the lowest protein (<... more
The effect of extraction methods using water, acid, Alcalase and Cellulase was studied on structure-bioactivity relationship of alginates from Colpomenia peregrina. Enzyme-assisted extractions produced alginates with the lowest protein (< 0.7%) and polyphenol (<5 mg GA/ g sample) contaminations. The molecular weight (Mw) of alginate extracted after acid treatment was 386.4 × 103 g/mol. The minimum Mw of 247.9 × 103 g/mol was determined for alginates extracted after Cellulase treatment. The specific volume of gyration (SVg) increased to > 0.57 cm3/g in enzymatically treated alginates. Alginate isolated after Cellulase treatment was nontoxic and stimulated RAW264.7 macrophage cells to release nitric oxide and inflammatory cytokines such as TNF-α, IL-1, IL-6, IL-10 and IL-12. The DPPH radical scavenging activity and reducing power were shown to be the highest for enzyme-treated. This study demonstrates the lab scale feasibility of extraction of alginate with the highest immunomodulatory and antioxidant properties.
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Chemical composition, rheological properties and antioxidant activities of Althaea officinalis flower gum were studied as a new source of thickening agent for application in food systems. The isolated gum comprised mainly carbohydrates... more
Chemical composition, rheological properties and antioxidant activities of Althaea officinalis flower gum were studied as a new source of thickening agent for application in food systems. The isolated gum comprised mainly carbohydrates (52.6 ± 0.8%), uronic acids (37.5 ± 0.5%), and proteins (7.1 ± 0.1%). Rhamnose (57.7%) was the major sugar; the polysaccharide backbone was chiefly composed of 1,2-linked rhamnose. The average molar mass of the polysaccharide was 33.3 Â 10 6 g/mol. Rheological behavior was determined as a function of concentration (0.5e5.0% w/v) and temperature (5.0e50 C). Polysaccharide solution steady-shear flow behavior was pseudoplastic and well-described with the Carreau model (R 2 ¼ 0.99). The degree of pseudoplasticity (N) of the solutions increased with increased concentration and decreased with increased temperature. Frequency sweeps indicated weak gel behavior at higher concentrations or lower temperatures. Moderate DPPH radical scavenging activity and ferric reducing power was observed for the extracted polysaccharide.
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The relationship between molecular structure and bioactivity was evaluated for alginates obtained under different extraction methods (water, acid, alcalase and cellulase) from Sargassum angustifolium. The use of enzymes considerably... more
The relationship between molecular structure and bioactivity was evaluated for alginates obtained under different extraction methods (water, acid, alcalase and cellulase) from Sargassum angustifolium. The use of enzymes considerably reduced protein (from 14.58% to <0.4%) and polyphenol (from 16.0% to <1.7 mg GA/g sample) contaminations of alginates compared to those of water and acid. The FT-IR spectrum revealed that extraction method did not affect the structure of the recovered alginates. The highest molecular weight (M w) (557.1 × 10 3 g/mol) was found in acid treated alginate while the M w of cellulase assistant alginate (356.2 × 10 3 g/mol) was the minimum. The SV g values varied from 2.79–5.17 cm 3 /g revealing the loosed conformational structures of alcalase and cellulase assistant alginates. Alcalase assistant alginate stimulated RAW264.7 cells to release nitric oxide and inflammatory cytokines TNF-, IL-1, IL-6, IL-10 and IL-12. Enzyme treated alginates showed maximum DPPH radical scavenging activity and reducing power. Therefore, the present results showed the determinant effect of pretreatment during the extraction process of alginate and the beneficial influence of enzymatic process when biological functions of alginates are of high interest in the industry.
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Response surface methodology was employed to optimize the ultrasound-assisted extraction of crude poly-saccharides from the cell wall of Ulva intestinalis. The impacts of four independent variables including extraction temperature (X 1... more
Response surface methodology was employed to optimize the ultrasound-assisted extraction of crude poly-saccharides from the cell wall of Ulva intestinalis. The impacts of four independent variables including extraction temperature (X 1 50–90 °C), extraction time (X 2 20– 40 min), the ratio of water to raw material (X 3 50–70), and pH (X 4 7–9) were investigated through Box–Behnken experimental design. The experimental data were adequately fitted into a second-order polynomial model, and optimized conditions were as follows: extraction temperature 66 °C, extraction time 40 min, water to raw material ratio 50, and pH 7.0. Fourier transform infrared (FT-IR) results revealed the presence of sulfate esters indicated by the peaks at 850 and 1256 cm −1 derived from the bending vibration of C–O–S and stretching vibration of S–O of sulfate. The experimental yield achieved under these conditions was 8.30 %, which was well in close agreement with the value (8.36 %) predicted by the response surface methodology (RSM) model. The extracted polysaccharides exhibited appreciable 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging and reducing power as well as macrophage-stimulating capacity indicating their potential value for health and food industry.
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The effects of sulfate and protein contents as well as molecular weights of the sulfated-glycoproteins (NF2) from Codium fragile on the immunomodulation were systematically investigated. The obtained NF2 derivatives displayed various... more
The effects of sulfate and protein contents as well as molecular weights of the sulfated-glycoproteins (NF2) from Codium fragile on the immunomodulation were systematically investigated. The obtained NF2 derivatives displayed various amounts of proteins (2.3–8.7%) and sulfates (4.3–8.1%) as well as different molecular weights (47.3–128.0 × 103 g/mol). NF2 was not able to stimulate RAW264.7 cells to release NO without its protein moiety, which was essential to activate NF-κB pathway through the degradation and phosphorylation of IκB- and the subsequent translocation of p65/p50 complex in the cell nucleus. In addition, the proteins in NF2 were required to trigger MAPK pathway for the phosphorylation of ERK1/2, p38, and JNK1/2 as well as the nuclear translocation of c-JUN and c-FOS. However, the protein moiety itself could not activate RAW264.7 cells, thus the complex formation of the polysaccharide and protein moieties in NF2 was pivotal to stimulate macrophage cells.
Water-soluble anionic macromolecules isolated from Codium fragile and fractionated using ion-exchange chromatography were investigated to determine their molecular characteristics and immunostimulating activity. The crude molecules and... more
Water-soluble anionic macromolecules isolated from Codium fragile and fractionated using ion-exchange chromatography were investigated to determine their molecular characteristics and immunostimulating activity. The crude molecules and fractions (F1, F2, and F3) consisted mostly of carbohydrates (44.1–80.5%), sulfates (3.2–22.2%) and proteins (3.0–15.7%) with small amounts of uronic acids (1.1–4.2%), and included different levels of mannose (91.3–18.7%), glucose (62.7–8.6%) and galactose (37.5–59.5%). These molecules contained one or two subfractions with molecular weights (Mw) ranging from 148 103 to 4,879 103 g/mol. The crude, F1 and F2 stimulated RAW264.7 cells to produce considerable amounts of pro-inflammatory mediator nitric oxide (NO) and cytokines. The treatment of sample molecules facilitated the degradation of Iκ-B and phosphorylation of MAPK in RAW264.7 cells, suggesting that they might stimulate RAW264.7 cells through the activation of NF-κB and MAPK pathway. Proteins in fraction F2 were essential to possess its bioactivity and its main backbone was composed of mixed linkages of (1→3)-α and β-D-mannan.
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Sulfated polysaccharides were extracted from Ulva pertusa and fractionated to obtain the most immunostimulating fraction (F2). The glycosidic linkages of the polysaccharides in the fraction F2 were determined using GC-MS and 2D-NMR... more
Sulfated polysaccharides were extracted from Ulva pertusa and fractionated to obtain the most immunostimulating fraction (F2). The glycosidic linkages of the polysaccharides in the fraction F2 were determined using GC-MS and 2D-NMR spectroscopy after chemical modifications, including reduction and desulfation under various conditions. Methanol was used as a sulfate acceptor for the removal of sulfates from the polysaccharides. When the desulfation was carried out at 120 oC, the sulfates were removed up to 90.1% from the F2 fraction without considerable backbone degradation. The GC-MS analysis as well as NMR spectra revealed that the backbone of the polysaccharides was mainly composed of -(1→4)-L-rhamnopyranosyl, -(1→4)-D-glucuronosyl, -(1→2)-L-rhamnopyranosyl and -(1→4)-D-xylopyranosyl residues with branches at O-2 position of rhamnose. The sulfate groups were mostly found on glucuronic acid at O-3 position.
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The nutritional compositions of two edible red and green seaweeds (Gracilaria salicornia and Ulva lactuca, respectively) were determined. In general, these species demonstrated low lipid contents ranging between 0.99 and 2.00 g/ 100 g dry... more
The nutritional compositions of two edible red and green seaweeds (Gracilaria salicornia and Ulva lactuca, respectively) were determined. In general, these species demonstrated low lipid contents ranging between 0.99 and 2.00 g/ 100 g dry weight (d. w.) and proved to be an enhanced source of minerals especially in G. salicornia with 38.91 g/ 100 g d. w. The crude protein values varied between 9.58-10.69 g/ 100 g d. w.. Amounts for total amino acids were 889.78 ± 22.64 mg/(g protein d. w.) in G. salicornia and 543.3 ± 15.14 mg/(g protein d. w.) in U. lactuca. The most abundant fatty acids were C12:0, C16:0, C20:4 ω6, C22:5 ω3 and in addition C18:1 in G. salicornia. Both of these seaweeds were balanced sources of ω3 and ω6 acids respectively, with a ratio ω6/ω3 that varied between 1.2-1.17. Unsaturated fatty acids were higher in these two seaweeds than saturated fatty acids. Among the investigated seaweeds, high levels of K (2414.02-11380.06 mg/ 100 g d. w.) were observed and amounts of Ca, Na and Fe were higher than those reported for land plants. Thus, G. salicornia and U. lactuca may be utilized as value-added products.
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This study was conducted to create a nutritional database on brown seaweeds, and to popularize their consumption and utilization in Iran. The fatty acid contents, amino acids profiles and certain mineral elements composition of some brown... more
This study was conducted to create a nutritional database on brown seaweeds, and to popularize their consumption and utilization in Iran. The fatty acid contents, amino acids profiles and certain mineral elements composition of some brown seaweeds Padina pavonica (L.) Thivy in Taylor, Dictyota dichotoma (Huds.) Lamour., Colpomenia sinuosa (Roth) Derb. et Sol. were determined. Total lipid content ranged from 1.46 ± 0.38 to 2.94 ± 0.94 g/ 100 g dry weight and the most abundant fatty acids were C16:0, C18:1, C20:4 ω6 and C20:5 ω3. The unsaturated fatty acids predominated in all species and had balanced sources of ω3 and ω6 acids. Highest total PUFA levels were found in C. sinuosa. The protein content of D. dichotoma was 17.73 ± 0.29 g/ 100 g d. w., significantly higher than the other seaweeds examined. Among amino acids essential in relation to human nutrition, Methionine (in D. dichotoma and P. pavonica) and lysine (in C. sinuosa) were found in high concentrations. The crude fibre content varied between 9.5 ± 11.6 g/ 100 g d. w. in all species. Chemical analysis indicated that ash content was between 27.02 ± 0.6 to 39.28 ± 0.7 g/ 100 g d. w. and that these seaweeds contained higher amounts of both macro minerals (7308 – 9160 mg/100g d. w.; Na, K, Ca) and trace elements (263 – 1594 mg/100 g d. w.; Fe, Ni, Mn, Cu, Co) than have been reported for edible land plants. C. sinuosa had the highest amount of Ca, Fe and a considerable content of Na was found in P. pavonica.
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Four Proteoglycans were sequentially extracted from Hypsizygus marmoreus using 0.1 M NaOH (alkali-soluble proteoglycans [F1] and alkali-insoluble proteoglycans [F3]) and 0.1 M HCl (acid-soluble proteoglycans [F2] and acid-insoluble... more
Four Proteoglycans were sequentially extracted from Hypsizygus marmoreus using 0.1 M NaOH (alkali-soluble proteoglycans [F1] and alkali-insoluble proteoglycans [F3]) and 0.1 M HCl (acid-soluble proteoglycans [F2] and acid-insoluble proteoglycans [F4]), and their structures and immunomodulatory activities were investigated. The proteoglycans were found to contain carbohydrates (19.8-82.4%) with various amounts of proteins (7.7-67.3%), and glucose was the major monosaccharide unit present, with trace amounts of galactose. The molecular weights (Mw) and the radius of gyration (Rg) of these proteoglycans showed ranges of 16104-19,545104 g/mol and 35-148 nm, respectively, showing significant variations in their molecular conformations. The backbones of F1 and F2 were mainly connected through -(13), (14) and -(16)-glycosidic linkages with some branches. The F1 and F2 proteoglycans significantly stimulated Raw264.7 cells to release nitric oxide (NO), prostaglandin E2 (PGE2) and various cytokines, such as IL-1β, TNF-α and IL-6 by inducing their mRNA expressions.
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Sulfated polysaccharides isolated from Ulva pertusa and fractionated using anion-exchange chromatography were investigated to determine their molecular characteristics and bioactivities. The crude and fractionated polysaccharides (F1, F2... more
Sulfated polysaccharides isolated from Ulva pertusa and fractionated using anion-exchange chromatography were investigated to determine their molecular characteristics and bioactivities. The crude and fractionated polysaccharides (F1, F2 and F3) were mainly composed of carbohydrates (59.9 to 65.9%), sulfates (11.6 to 15.3%) and uronic acid (7.30 to 16.4%) with small amounts of proteins (1.40 to 4.80%). Rhamnose (62.5 to 80.7%) was the major monosaccharide unit of these polysaccharides with different levels of glucose (13.5 to 27.4%) and xylose (2.74 to 11.5%). The polysaccharides contained one or two major subfractions with average molecular mass (Mw) ranging from 51.1103 to 1690103g/mol. The relatively low in vitro anticancer activity of the polysaccharides (22.3 to 42.4%) suggested that they had little cytotoxicity against the cancer cell line (AGS). On the other hand, the polysaccharides significantly stimulated RAW 264.7 cells, inducing considerable amounts of nitric oxide and various cytokines production, which suggested that they could be strong immunostimulators.
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The effects of constant light (24L: 00D), no light (00L: 24D) and two light:dark periods (18L:06D;12L:12D) on the growth, stress and haematological variables were assessed in juvenile great sturgeon, Huso huso. During the 8-week... more
The effects of constant light (24L: 00D), no light (00L: 24D) and two light:dark periods (18L:06D;12L:12D) on the growth, stress and haematological variables were assessed in juvenile great sturgeon, Huso huso. During the 8-week experimental period, juveniles (22.5 ± 0.6 g) were kept under a150 lx light intensity in fiberglass tanks (0.8m2, 500 L). Differences in growth were insignificant during the experiment, but lactate levels were higher in the 00L: 24D and 24L: 00D photoperiods compared with 12L: 12D and 18L:06D photoperiods. Cortisol levels did not show differences among the various photoperiods. At the end of the experimental period, ¢sh reared under a 12L:12D photoperiod had higher haemoglobin values and erythrocyte numbers than in the other photoperiods, while no differences were found between groups with regard to haematocrit values or leucocyte numbers. The highest survival rate (89%) was observed in the 12L: 12D period in which the levels of lactate and cortisol as stress indicators were minimal. The results indicate that various photoperiods cause different stress levels in juvenile great sturgeon and have no significant effects on growth, at least in short time periods.