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Sustainable production based on renewable biomass and efficient bioprocesses are important elements in the growing blue bioeconomy. The traditional Laminaria hyperborea alginate production disposes approximately 80 % of the raw material, ignoring large amounts of potential high-value products from the alga. Particularly, the leaf fraction of the seaweed is often disregarded. This study aimed to characterize high value products from the alginate production side-stream – focusing on the leaf biomass and particularly targeting the phenolic content. After extraction and solvent optimization, 60 % methanol was used for the extraction. The extract was further purified with PuriFlash and semi-preparative chromatography and increasing phenolic selectivity and purity was observed with TPC and qNMR, as well as antioxidant activity (ORAC). In the purified fractions, the LR LC-MS analyses displayed several masses, where 96 % (n = 1376) were of lower molecular weights (< 800 Da). Fifteen high value compounds were further identified using HR LC-MS (MS/MS) and/or NMR. This also included non-phenolics such as fucoxanthin, aliphatic acids and mannitol. Nonetheless, most compounds were identified as the targeted phenolics, consisting of lower molecular weight phenolic acids (salicylic acid, veratric acid, 5-caboxyvanillic acid, sinapic acid, 5-sulfosalicylic acid, vanillic acid 4-sulfate, and dihydrocaffeic acid 3-sulfate) and phlorotannins (trimer, tetramer, hexamer, and a sulfated dimer). None of the identified phenolics have previously been reported in L. hyperborea. In general, a high occurrence of sulfated phenolic compounds was observed and a sulfated diphlorethol/difucol was characterized for the first time. The isolation and characterization of high value components in the leaf biomass of L. hyperborea strongly supports the development of a total utilization of commercial alginate production. The characterization also adds information on the phenolic content of seaweeds at a molecular level, valuable to research on seaweed biosynthesis and development, chemical ecology, and ocean monitoring. publishedVersion

Three alginates with fundamentally different block structures, poly-M, poly-G, and poly-MG, have been investigated upon ionic crosslinking with chitosan oligosaccharides (CHOS), using circular dichroism (CD), rheology, and computer simulations, supporting the previously proposed gelling principle of poly-M forming zipper-like junction zones with chitosan (match in charge distance along the two polyelectrolytes) and revealing a unique high gel strength poly-MG chitosan gelling system. CD spectroscopy revealed an increased chiroptical activity exclusively for the poly-M chitosan gelling system, indicative of induced conformational changes and higher ordered structures. Rheological measurement revealed gel strengths (G′ < 900 Pa) for poly-MG (1%) CHOS (0.3%) hydrogels, magnitudes of order greater than displayed by its poly-M analogue. Furthermore, the ionically crosslinked poly-MG chitosan hydrogel increased in gel strength upon the addition of salt (G′ < 1600 at 50 mM NaCl), suggesting a stabilization of the junction zones through hydrophobic interactions and/or a phase separation. Molecular dynamics simulations have been used to further investigate these findings, comparing interaction energies, charge distances and chain alignments. These alginates are displaying high gel strengths, are known to be fully biocompatible and have revealed a broad range of tolerance to salt concentrations present in biological systems, proving high relevance for biomedical applications.

The structure of fucoidan isolated from

Fucoidans are polysaccharides and constituents of cell walls of brown algae such as Laminaria hyperborea (LH). They exhibit promising effects regarding age-related macular degeneration (AMD). However, the safety of this compound needs to be assured. The focus of this study lies on influences of an LH fucoidan on the retinal pigment epithelium (RPE). The high-molecular weight LH fucoidan Fuc1 was applied to primary porcine RPE cells, and a tetrazolium (MTT) cell viability assay was conducted. Further tests included a scratch assay to measure wound healing, Western blotting to measure expression of retinal pigment epithelium-specific 65 kDa protein (RPE65), as well as immunofluorescence to measure uptake of opsonized fluorescence beads into RPE cells. Lipopolysaccharide was used to proinflammatorily activate the RPE, and interleukin 6 (IL-6) and interleukin 8 (IL-8) secretion was measured. RPE/choroid cultures were used to assess vascular endothelial growth factor (VEGF) secretion. Real-time polymerase chain reaction (real-time PCR) was performed to detect the gene expression of 91 different genes in a specific porcine RPE gene array. Fuc1 slightly reduced wound healing, but did not influence cell viability, phagocytosis or RPE65 expression. Fuc1 lowered IL-6, IL-8 and VEGF secretion. Furthermore, Fuc1 did not change tested RPE genes. In conclusion, Fuc1 does not impair RPE cellular functions and shows antiangiogenic and anti-inflammatory activities, which indicates its safety and strengthens its suitability concerning ocular diseases.

The structure of fucoidan isolated from Laminaria hyperborea was elucidated and chemically tailored in order to obtain a clear structure–function relationship on bioactive properties with a minimal amount of variations among the tested molecules. Analysis revealed a sugar composition of 97.8% fucose and 2.2% galactose. Analysis of the glycosidic linkages showed (1→3)-α-l-fuco-pyranose (31.9%) to be the dominant residue, followed by 1→2-linked (13.2%) and 1→4-linked (7.7%) fuco-pyranose as well as a high degree of branching (22.4%). Inductively coupled plasma mass spectrometry (ICP-MS) revealed a sulfate content of 53.8% (degree of sulfation (DS) = 1.7). Raman spectroscopy determined SO4 located axial at 4C and equatorial at 2C as well as an absence of acetylation. SEC-MALS analysis determined a high molecular weight (Mw = 469 kDa), suggesting a highly flexible main chain with short side chains. Both chemical shifts of the fucoidan, proton, and carbon were assigned by NMR and revealed a highly heterogeneou...

Background: Sulfated fucans show interesting effects in the treatment of ocular diseases (e.g., age-related macular degeneration), depending on their chemical structure. Here, we compared three purified sulfated fucans from Laminaria hyperborea (LH) regarding cell viability, oxidative stress protection, and vascular endothelial growth factor (VEGF) secretion in ocular cells. Methods: High-molecular-weight sulfated fucan (Mw = 1548.6 kDa, Fuc1) was extracted with warm water and purified through ultrafiltration. Lower-molecular-weight samples (Mw = 499 kDa, Fuc2, 26.9 kDa, Fuc3) were obtained by mild acid hydrolysis of ultrapurified sulfated fucan and analyzed (SEC-MALS (Size-exclusion chromatography-Multi-Angle Light Scattering), ICP-MS, and GC). Concentrations between 1 and 100 &micro, g/mL were tested. Cell viability was measured after 24 h (uveal melanoma cell line (OMM-1), retinal pigment epithelium (RPE) cell line ARPE-19, primary RPE cells) via MTT/MTS (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide/3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Oxidative stress protection was determined after 24 h (OMM-1, ARPE-19). VEGF secretion was analyzed via ELISA after three days (ARPE-19, RPE). Results: Fuc2 and Fuc3 were antiproliferative for OMM-1, but not for ARPE. Fuc1 protected OMM-1. VEGF secretion was lowered with all fucans except Fuc3 in ARPE-19 and RPE. The results suggest a correlation between molecular weight and biological activity, with efficiency increasing with size. Conclusion: The LH sulfated fucan Fuc1 showed promising results regarding VEGF inhibition and protection, encouraging further medical research.

In research activities toward new electrolyte materials for energy devices, the new tetracyanidoborates [Li(C8H16O4)2][B(CN)4] (1), [Na(C8H16O4)2][B(CN)4] (2), [Li(C10H20O5)][B(CN)4] (3), and [Na(C10H20O5)][B(CN)4] (4), which contain lithium and sodium metal cations coordinated by macrocyclic polyether molecules, were synthesized and characterized. Their structures were determined by single-crystal X-ray diffraction measurements. Compounds 1 and 2 form orthorhombic crystals built up from isolated ion pairs. The alkaline metal cation is coordinated by eight oxygen atoms of two 12-crown-4 (12Cr4) crown ether molecules. Compounds 3 and 4 crystallize in the monoclinic crystal system and are constructed from salt chains that extend in one direction. The Na compound has double rows of approximately face-to-face oriented complex cations, which are bridged by two CN groups of each tetracyanidoborate anion. The Li compound contains single strands. In both cases, each anion has two coordinated and two uncoordinated CN groups. The different bonding situations in all four compounds are characterized by IR, Raman, and NMR spectroscopy. Electrochemical spectroscopy was performed to obtain the overall specific conductivity of 1 and 3. Furthermore, differential scanning calorimetry (DSC) measurements revealed melting points below 200 °C and decomposition temperatures above 230 °C.

Alginates are polysaccharides that are widely used in relation to their ability to form gels. Recently we reported that alginates may also form gels with chitosan oligomers as crosslinkers (Khong, Aarstad, Skjåk-Bræk, Draget, & Vårum, 2013). The purpose of the present study was to characterize alginate gels crosslinked with calcium and chitosan oligomers. Using two different alginates of similar molecular weights but different chemical composition, i.e. guluronic acid content of 46 and 68%, we found that both alginates could form homogeneous gels with calcium and chitosan oligomers separately and without syneresis. Systematic combinations of calcium and chitosan oligomers as crosslinkers were tested, showing that up to 50% of the calcium could be substituted with chitosan oligomers without reduction in gel strength or increased syneresis for the alginate with the lowest guluronic acid content. Furthermore, the kinetics of the combined gels were different from pure calcium alginate gels. This is a submitted manuscript of an article published by Elsevier Ltd in Carbohydrate Polymers, 12 September 2016.