Xiaoting Fu

Extraction and Identification of Phlorotannins from the Brown Alga, Sargassum fusiforme (Harvey) Setchell

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene), which are unique compounds from marine brown algae. In our present study, a procedure for extraction and enrichment of phlorotannins from S. fusiforme with highly antioxidant potentials was established. After comparison of different extraction methods, the optimal extraction conditions were established as follows. The freeze-dried seaweed powder was extracted with 30% ethanol-water solvent with a solid/liquid ratio of 1:5 at temperature of 25 °C for 30 min. After extraction, the phlorotannins were fractioned by different solvents, among which the ethyl acetate fraction exhibited both the highest total phlorotannin content (88.48 ± 0.30 mg PGE/100 mg extract) and the highest antioxidant activities. The extracts obtained from these locations were further purified and characterized using a modified UHPLC-QQQ-MS method. Compounds with 42 different molecular weights were detected and tentatively identified, among which the fuhalol-type phlorotannins were the dominant compounds, followed by phlorethols and fucophlorethols with diverse degree of polymerization. Eckol-type phlorotannins including some newly discovered carmalol derivatives were detected in Sargassum species for the first time. Our study not only described the complex phlorotannins composition in S. fusiforme, but also highlighted the challenges involved in structural elucidation of these compounds.

Factors affecting water resistance of alginate/gellan blend films on paper cups for hot drinks

Enhanced film water resistance of paper cups was achieved by physically blending sodium alginate (NaAlg) and gellan gum with crosslinking treatment. Pure and blended films were prepared and characterized via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and positron annihilation lifetime spectroscopy (PALS). Results demonstrated excellent compatibility between the two polysaccharides. Total mixed solution concentration, component ratio, glycerol content, Ca2+ concentration, crosslinking time, and dry temperature affected water resistance. Water permeability (WP) and swelling degree (SD) were tested. Optimal conditions were as follows: total mixed solution concentration, 2.4% (m/v); component ratio, 2:1; glycerol content, 0.5% (m/v); Ca2+ concentration, 5% (m/v); crosslinking time, 5min; and dry temperature, 50°C. WP and SD values were 78.1×10-8g/msPa and 66.3%, respectively. Properties of the films showed the synergistic effect between NaAlg and gellan, which can be used for water-resistant film coating on paper cups for hot drinks.

Characterization of Polysaccharides Extracted from a Cultivated Brown Alga Costaria costata During the Harvest Period

In this study, variations in composition and properties of polysaccharides isolated from brown algae Costaria costata were analyzed. The algae were collected from May to July of the harvest period. The carbohydrates alginate and fucoidan were extracted with selected solvents. 1H Nuclear magnetic resonance and rheology were used to investigate the monomer composition and rheological characteristics of alginate. Gas chromatography and Fourier transform-infrared spectroscopy were employed to investigate the compositional properties of purified fucoidan. The results indicated that the composition and properties of alginate and fucoidan varied during the life of this alga. The alginate from the alga harvested in May and June had a higher molecular weight, viscosity, and proportion of mannuronic acid, whereas that harvested in July had a lower molecular weight and viscosity but a higher proportion of guluronic acid. The alginate from C. costata had a higher molecular weight and a different mannuronic acid: guluronic acid ratios compared with other algae; thus, it could be used in the chemical, food, cosmetics, and pharmaceutical industries. Fucoidan content reached the maximum in June. Substantial changes in the molecular weight distribution, monosaccharide composition, and sulfate content occurred simultaneously. The fraction of fucose in the polysaccharides decreased significantly from June to July, whereas that of mannose increased. This alga can be harvested during different growth periods to obtain fucoidans and alginates with different compositions and, therefore, with different biological properties.

Development of a simple multi-residue determination method of 80 veterinary drugs in Oplegnathus punctatus by liquid chromatography coupled to quadrupole Orbitrap mass spectrometry

A simple, rapid and sensitive multi-residue analytical method was developed and validated for 80 veterinary drugs in Oplegnathus punctatus using ultrahigh performance liquid chromatography-Orbitrap high resolution mass spectrometry (LC-HRMS). The analytes belong to 12 different families include benzimidazoles, β-lactams, lincosamides, macrolides, nitromidazoles, quinolones, sulfonamides and trimethoprim, tetracyclines, triphenylmethane dyes, amphenicols, nonsteroidal estrogens and steroid hormones. The sample preparation was optimized base on QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure. A very simple and sufficient preparation procedure without salting-out and complex clean-up process was studied. It had been proved that water in the extract was helpful for extracting hydrophilic compounds and precipitating the lipids during the subsequent cleaning process. In addition, an appropriate percent of methanol was necessary to some analytes. Finally, a mixture of acetonitrile, methanol and water (3:1:1, v/v/v) which include 1% acetic acid and 10mM ethylenediaminetetraacetic acid disodium salt 2-hydrate was selected as the extraction solvent, and the clean-up step consisted of a low temperature procedure and two times of high-speed centrifugation to deproteinize and remove lipids. The detection and quantification of all compounds were performed by ultrahigh performance liquid chromatography coupled with electrospray ionization quadrupole Orbitrap high resolution mass spectrometry in positive and negative ion mode. This methodology was validated according to the Commission Decision 2002/657/EC and SANTE/11945/2015. The recoveries ranged from 60.74%-109.85% with relative standard deviations (RSDs)<20%. The limits of quantification (LOQs) were 0.25-25ug/kg, for the analytes which the MRL or MRPL had been established in fish tissue, the LOQs were all lower than their own legal tolerances. The values of decision limit (CCα) and detection capability (CCβ) were in the range of 1.91-1001.13ug/kg and 3.52-1002.26ug/kg, respectively. This validated method has been successfully applied on the determination of veterinary drugs in real commercial oplegnathus punctatus samples.

Enzymatic desulfation of the red seaweeds agar by Marinomonas arylsulfatase

Agar and sulfated galactans were isolated from the red seaweeds Gracilariopsis lemaneiformis and Gelidium amansii. A previously purified arylsulfatase from Marinomonas sp. FW-1 was used to remove sulfate groups in agar and sulfated galactans. After enzymatic desulfation, the sulfate content decreased to about 0.16% and gel strength increased about two folds. Moreover, there was no difference between the DNA electrophoresis spectrum on the gel of the arylsulfatase-treated agar and that of the commercial agarose. In order to reveal the desulfation ratio and site, chemical and structural identification of sulfated galactan were carried out. G. amansii sulfated galactan with 7.4% sulfated content was composed of galactose and 3,6-anhydro-l-galactose. Meanwhile, G. lemaneiformis sulfated galactan with 8.5% sulfated content was composed of galactose, 3,6-anhydro-l-galactose, 2-O-methyl-3,6-anhydro-l-galactose and xylose. Data from 13C NMR, FT-IR, GC-MS provided evidence of sulfate groups at C-4 and C-6 of d-galactose and C-6 of l-galactose both in GRAP and GEAP. Data from GC-MS revealed that desulfation was carried out by the arylsulfatase at the sulfate bonds at C-4 and C-6 of d-galactose and C-6 of l-galactose, with a desulfation ratio of 83.4% and 86.0% against GEAP and GRAP, respectively.

Optimized water vapor permeability of sodium alginate films using response surface methodology

The water vapor permeability (WVP) of films is important when developing pharmaceutical applications. Films are frequently used as coatings, and as such directly influence the quality of the medicine. The optimization of processing conditions for sodium alginate films was investigated using response surface methodology. Single-factor tests and Box-Behnken experimental design were employed. WVP was selected as the response variable, and the operating parameters for the single-factor tests were sodium alginate concentration, carboxymethyl cellulose (CMC) concentration and CaCl2 solution immersion time. The coefficient of determination (R2) was 0.97, indicating statistical significance. A minimal WVP of 0.389 8 g·mm/(m2·h·kPa) was achieved under the optimum conditions. These were found to be a sodium alginate concentration, CMC concentration and CaCl2 solution immersion time at 8.04%, 0.13%, and 12 min, respectively. This provides a reference for potential applications in manufacturing film-coated hard capsule shells.