Aphanothece Sacrum Research Articles

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides.

Cyanobacteria are regarded as very eco-friendly microreactors for the production of various biomolecules such as polysaccharides by fixing not only carbon but also nitrogen in water. Cyanobacterial polysaccharides having various functional groups such as hydroxyls, carboxyls, sulfates, etc. have the ability to interact with metals or inorganics, to create bionanocomposites. Sacran, a supergiant cyanobacterial anionic polysaccharide extracted from the extracellular matrix of Aphanothece sacrum which is mass-cultivated in freshwater, is mainly used to create functional bionanocomposites. Gel-type bionanocomposites of sacran with various metal cations are formed and showed photoresponsive functions. Metal recovery is performed from the sacran bionanocomposite gels. Sacran chains are complexed with multi-wall carbon nanotubes (MWCNT) to give viscose dispersion from which MWCNT bionanocomposites can be collected by electrophoresis. The MWCNT/sacran dispersion retains the capability of adsorbing various metal ions to form hardened hydrogel beads. Finally, natural inorganic sepiolite can be used for sacran bionanocomposites which show an efficient neodymium ion adsorption ability. Thus, cyanobacterial polysaccharides are useful for preparing eco-friendly and functional bionanocomposites with various hard materials.

Anti-inflammatory Effect of Sacran on Atopic Dermatitis

Atopic dermatitis (AD) is a chronic skin disease characterized by inflammation, pruritus, and eczematous lesions. Recently, sacran, a new polysaccharide isolated from cyanobacterium Aphanothece sacrum (Sur.) OKADA discovered by Suringar in the 19th century, has received considerable attention as a novel biomaterial. Previously, it was reported that sacran exhibits potent anti-inflammatory effects for skin diseases produced by various stimulants with optimum effective concentrations at 0.01% (w/v) and 0.05% (w/v) in rats and mice. Importantly, we demonstrated clinically that almost all of the average scores for AD symptoms in patient treated with sacran solutions were improved. In AD model mice, sacran treatment markedly down-regulated inflammatory cytokine and chemokine mRNA levels compared with non-treated controls. Furthermore, sacran solution significantly suppressed inflammation response in RAW264.7 cells. In RBL-2H3 cells, the sacran solution significantly lowered degranulation. Taken together, our studies suggest sacran may have the potential to improve AD through functional recovery of skin barrier and anti-inflammatory effects.

Anti-allergic effects of novel sulfated polysaccharide sacran on mouse model of 2,4-Dinitro-1-fluorobenzene-induced atopic dermatitis

In this study, in order to investigate the potential of the novel polysaccharide sacran from Aphanothece Sacrum for development of atopic dermatitis (AD), we evaluated the potential of pretreatment with topical sacran to prevent the development of hapten (dinitrofluorobenzene: DNFB)-induced AD-like disease in mice. In the AD model mice, sacran markedly ameliorated AD symptoms such as scratching behavior and edema in ear. In addition, sacran significantly increased water content of the stratum corneum which regulates the skin barrier function. Furthermore, sacran significantly inhibited inflammatory cytokine and chemokine mRNA levels in the dermatitis skin as well as the IgE antibody level in serum. Sacran inhibited inflammatory cytokines mRNA production from Jurkat cells derived from human leukemia T cells after stimulation with phorbol 12-myristate 13-acetate/ionomycin. Meanwhile, sacran did not inhibit the proliferation of primary B cells stimulated with lipopolysaccharide. These results suggest that sacran has good anti-allergic effect on AD model mice, probably due to the amelioration of skin barrier function and suppression of immune responses.

Tough and Porous Hydrogels Prepared by Simple Lyophilization of LC Gels.

Porous hydrogels possessing mechanical toughness were prepared from sacran, a supergiant liquid crystalline (LC) polysaccharide produced from Aphanothece sacrum. First, layered hydrogels were prepared by thermal cross-linking of film cast over a sacran LC solution. Then, anisotropic pores were constructed using a freeze-drying technique on the water-swollen layered hydrogels. Scanning electron microscopic observation revealed that pores were observable only on the side faces of sponge materials parallel to the layered structure but never on the top or bottom faces. The pore size, porosity, and swelling behavior were controlled by the thermal-cross-linking temperature. To clarify the freezing effect, a freeze–thawing method was used for comparison. The freeze–thawed hydrogels also formed layers but no pores. The mechanical properties and network structures of hydrogels were also studied, clarifying that porous hydrogels, even those with a high quantity of pores, were tough owing to the pores orienting along the layer direction like tunnels.

Two new sacrolide-class oxylipins from the edible cyanobacterium Aphanothece sacrum

Two new sacrolide-class oxylipins from the edible cyanobacterium Aphanothece sacrum

Aphanothece sacrum (Sur.) Okada Prevents Cataractogenesis in Type 1 Diabetic Mice.

Aphanothece sacrum (Sur.) Okada is a species of cyanobacteria found in Japan. Although it has been used in local cuisine in Kyushu, Japan, for 250 y, little is known about its beneficial effect as food. The daily intake of health beneficial phytochemicals is believed to be useful for preventing lifestyle-related diseases, such as diabetic cataracts. In this study, the inhibitory effect of freeze-dried A. sacrum (Asa) on the formation of diabetic cataracts (DCs) was evaluated. Type 1 diabetes was induced in mice using streptozotocin (STZ). The mice were divided into two groups: one was fed a normal diet (DM-control group) and the other was fed a diet containing 1% Asa (DM-Asa group). During the study, changes in blood glucose levels and the amount of food and water consumed were measured. After 3 mo, the amount of Nε-(carboxymethyl)lysine (CML), an oxidative stress marker, in the lens was measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Although the blood glucose levels (p=0.91) and food consumption did not significantly change in any group, the oral administration of Asa tended to suppress CML accumulation (p=0.15) and significantly inhibited the progression of cataractogenesis in the diabetic lens compared with that reported for the normal diet (p=0.009). These results suggested that the daily intake of A. sacrum prevents the pathogenesis of cataracts, and indicated that may reduce the number of DC patients.

Anti-inflammatory Effects of Novel Polysaccharide Sacran Extracted from Cyanobacterium Aphanothece sacrum in Various Inflammatory Animal Models.

The goal of this study was to investigate the topical anti-inflammatory effects of the megamolecular polysaccharide sacran extracted from cyanobacterium Aphanothece sacrum using various inflammatory animal models. Sacran showed potent anti-inflammatory effects with optimum effective concentrations at 0.01 and 0.05% (w/v). Sacran markedly inhibited paw swelling and neutrophil infiltration in carrageenan-induced rat paw edema. Additionally, 6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone-3-propionyl-carboxylic acid (DMEQ)-labeled sacran had the ability to penetrate carrageenan-induced rat paw skin rather than normal skin. Also, sacran significantly suppressed kaolin-induced and dextran-induced rat paw edema throughout the duration of the study. Furthermore, sacran significantly suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema and mRNA expression levels of cyclooxygenase (COX)-2 as well as pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Safety of sacran solution was verified by negligible cytotoxicity in HaCaT cells. These results suggest that sacran may be useful as a therapeutic agent against inflammatory skin diseases with no life-threatening adverse effects.

Uniaxial Swelling in LC Hydrogels Formed by Two-Step Cross-Linking

Molecularly oriented hydrogels of sacran, which is a supergiant liquid crystalline polysaccharide extracted from Aphanothece sacrum biomaterials, showing ultrahigh anisotropy of swelling is successfully prepared by two-step chemical cross-linking. Divinyl sulfone (DVS) works as a chemical cross-linker of sacran chains in a dilute aqueous solution to form hydrogels, but some of the added DVS remains in the hydrogel without cross-linking. The remaining DVS cross-links further with the preformed networks of sacran chains in liquid crystalline state during slow drying to produce in-plane oriented xerogels. The xerogels show heterogeneous anisotropy in the successive swellings steps; the linear swelling ratio in the thickness direction is 10000–40000-fold higher than that in the width direction due to the molecular orientation of the sacran hydrogels. X-ray diffraction imaging of the hydrogels reveal not only the orientation of the xerogel films but also the unusual orientation of water molecules binding to sa...

Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum.

Macroscopic gelatinous colonies of freshwater cyanobacterium Aphanothece sacrum, a luxury ingredient for Japanese cuisine, were found to contain a new oxylipin-derived macrolide, sacrolide A (1), as an antimicrobial component. The configuration of two chiral centers in 1 was determined by a combination of chiral anisotropy analysis and conformational analysis of different ring-opened derivatives. Compound 1 inhibited the growth of some species of Gram-positive bacteria, yeast Saccharomyces cerevisiae and fungus Penicillium chrysogenum, and was also cytotoxic to 3Y1 rat fibroblasts. Concern about potential food intoxication caused by accidental massive ingestion of A. sacrum was dispelled by the absence of 1 in commercial products. A manual procedure for degrading 1 in raw colonies was also developed, enabling a convenient on-site detoxification at restaurants or for personal consumption.

超巨大多糖類サクランの構造物性とバイオミメチックな機能創出

Cyanobacteria, which live in the rivers and sea, produce and secrete polysaccharides with functional groups such as carboxylic acid, sulfates, phosphates and amines that are responsible for ionic adsorption. Aphanothece sacrum,whose extracellular polysaccharide creates a jelly-like material (gels) which protects the cells, is mass cultured in fresh water only in Japan, and is grown with adsorbing metal ions from groundwater. The fact motivated us in the biomimetics concept to develop a metal-recycle material of the extracellular polysaccharide, which was here extracted by a successful alkaline elution method. The extracted polysaccharide was a new product and then it was named as “sacran”. Sacran adsorbed various multivalent metals as expected and formed the gels whose structure was formed a fibrous nanostructural network containing water revealed by cryogenic-TEM images. Freeze-drying of sacran formed spongy materials capable of In3+ preferential adsorption to form hydrogels from the mixed solution of In3+ and Sn4+ with concentrations below 40 mM. Electrolytic refinement of indium was made using the ion-complex hydrogels at room temperature to obtain indium metal foil at a pure grade over 99.9%. Thus epochal energy-saving methods for indium refinement were established using spongy hydrogels of cyanobacterial polyanions.

Clay-bionanocomposites with sacran megamolecules for the selective uptake of neodymium

Sacran, an anionic megamolecular polysaccharide extracted from the cyanobacterium Aphanothece sacrum, is an interesting biopolymer for developing functional clay-based bionanocomposites due to its colloidal and metal complexing properties. This work introduces novel bionanocomposites based on the assembly of sacran to sepiolite, a fibrous hydrated magnesium silicate, reporting some of their special features. Sacran–sepiolite films show tensile moduli about twice that of neat sacran films, and improved resistance and integrity in aqueous solutions. These materials can act as adsorbents of lanthanide ions, profiting from the well-known adsorption properties of sepiolite and the ability of sacran to complex rare earth and heavy metal ions. Sacran–sepiolite materials show a clear preference for Nd3+ ions over Ce3+, Eu3+ and Gd3+, and the results confirm the influence of the conformation of sacran chains in crystalline domains on the adsorption properties. In fact, only those materials prepared from concentrated sacran solutions, with the polysaccharide chains arranged as liquid crystals, and involving around 27% (w/w) of sepiolite showed a remarkable synergistic effect on the retention of Nd3+ ions, being promising as biosorbents for the effective and selective recovery of neodymium from aqueous media.

Potential use of a megamolecular polysaccharide sacran as a hydrogel-based sustained release system.

A megamolecular polysaccharide sacran was newly extracted from cyanobacterium Aphanothece sacrum. Sacran has many preferable properties for transdermal application, e.g. a safe biomaterial, a high moisturizing effect, a formation of film and hydrogel. Additionally, it was recently discovered that sacran has an anti-inflammatory effect for atopic dermatitis model mice. In this study, in order to evaluate the feasibility of sacran-hydrogel as a novel sustained release system, we prepared a sacran-hydrogel containing 4-biphenyl acetic acid (BPAA, an acidic drug), prednisolone (PD, a neutral drug) or chlorpheniramine maleate (CPM, a basic drug), and performed the in vitro release studies. The sacran-hydrogel containing BPAA, PD or CPM provided a sustained release profile in accordance with a quasi-Fickian diffusion model. Furthermore, the release rate of drugs from sacran-hydrogels can be controlled by adjusting the concentration of aluminum chloride as a cross linker. These results suggest the potential use of sacran-hydrogel as a sustained release system for drugs.

Double‐metal complexation of heterogels containing cyanobacterial polysaccharides

AbstractCryogenic‐transmission electron microscopy of metal complexes with cyanobacterial polysaccharides, sacran, extracted from Aphanothece sacrum biomaterials reveals that Nd3+ complexes form networks composed of thick strings with a thickness ranging 10–20 nm while Fe2+ ones make dense entanglement of very thin strings. When Fe2+ and Nd3+ double complexation occurs, dense nanonetworks composed of thick strings with a thickness around 10 nm are formed. Next we prepared heterogels by crosslinking poly(vinyl alcohol) chains in the presence of sacran and investigated the effects of double complexation on metal sorption. The amount of Nd3+ sorbed into the heterogels in the 1 : 1 miscible solution of Fe2+ and Nd3+ is higher than that in the solution containing only Nd3+, suggesting that Fe2+ assists the Nd3+ sorption. In addition, it is found that the amount of sorbed Nd3+ is much higher than that of sorbed Fe2+ even in the acidic condition of pH 2. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Spongy Hydrogels of Cyanobacterial Polyanions Mediate Energy-Saving Electrolytic Metal-Refinement

The freeze-drying of anionic megamolecules extracted from gelatinous cyanobacteria, Aphanothece sacrum, formed spongy materials capable of metal adsorption to form hydrogels. Cryogenic-transmission electron microscopy demonstrated that thicker nanofibers were formed in sacran/In3+ complexes than in sacran/Sn4+. The preferential sorption of In3+ into the hydrogels occurred in the mixed solution of In3+ and Sn4+ with concentrations below 40 mM. Since In3+ was condensed in the sponges, electrolytic refinement of indium was made using the ion-complex hydrogels at room temperature to obtain indium metal foil at a pure grade over 99.9%. Furthermore, the sponges were recovered and used again, to successfully obtain highly pure indium metal, in even the second and third trials. Thus epochal energy-saving methods for indium refinement were established using spongy hydrogels of cyanobacterial polyanions.

Anti-inflammatory effects of sacran, a novel polysaccharide from Aphanothece sacrum, on 2,4,6-trinitrochlorobenzene–induced allergic dermatitis in vivo

BackgroundSacran is a newly discovered sulfated polysaccharide extracted from an algae, Aphanothece sacrum, grown in a river of the Kyushu region in Japan. ObjectiveTo evaluate sacran's inhibitory effect in 2,4,6-trinitrochlorobenzene (TNCB)–induced allergic dermatitis in NC/Nga mice. MethodsSacran was extracted by acid and alkaline treatment of A sacrum cyanobacterial biomaterials. To sensitize mice, 150 μL of 5% TNCB was applied epicutaneously on the abdomen of each mouse on day 1 and challenged with 15 μL of 1% TNCB applied on the ear skin of mice on day 8 and then every other day to induce skin lesions. Serum levels of inflammatory markers were measured and histopathologic examination of ear skin specimens performed. On the other hand, sacran's transepidermal water loss was evaluated in 11 volunteer women with dry skin. ResultsEpicutaneous application of sacran in mice has significantly inhibited the development of allergic dermatitis skin lesions and reduced the number of scratching behavior episodes (P < .01). In addition, sacran efficiently inhibited IgE (P < .001), tumor necrosis factor α (P = .02), interleukin 4, interleukin 5, and interferon γ (P < .01; vs buffer in the TNCB group) production and eosinophilic infiltration in the chemical allergen–exposed ear skin. In addition, sacran-treated body regions of human volunteers with dry skin significantly reduced transepidermal water loss levels compared with exogenous hyaluronic acid (P < .01), which is known to improve skin moisture and exert skin barrier repair activity. ConclusionsThis study suggests that sacran exerts anti-inflammatory effects by improving skin barrier function and reducing TH2 cytokine production.

Mapping of Protein-Protein Interaction Sites in the Plant-Type [2Fe-2S] Ferredoxin

Knowing the manner of protein-protein interactions is vital for understanding biological events. The plant-type [2Fe-2S] ferredoxin (Fd), a well-known small iron-sulfur protein with low redox potential, partitions electrons to a variety of Fd-dependent enzymes via specific protein-protein interactions. Here we have refined the crystal structure of a recombinant plant-type Fd I from the blue green alga Aphanothece sacrum (AsFd-I) at 1.46 Å resolution on the basis of the synchrotron radiation data. Incorporating the revised amino-acid sequence, our analysis corrects the 3D structure previously reported; we identified the short α-helix (67-71) near the active center, which is conserved in other plant-type [2Fe-2S] Fds. Although the 3D structures of the four molecules in the asymmetric unit are similar to each other, detailed comparison of the four structures revealed the segments whose conformations are variable. Structural comparison between the Fds from different sources showed that the distribution of the variable segments in AsFd-I is highly conserved in other Fds, suggesting the presence of intrinsically flexible regions in the plant-type [2Fe-2S] Fd. A few structures of the complexes with Fd-dependent enzymes clearly demonstrate that the protein-protein interactions are achieved through these variable regions in Fd. The results described here will provide a guide for interpreting the biochemical and mutational studies that aim at the manner of interactions with Fd-dependent enzymes.

Gelation Behavior by the Lanthanoid Adsorption of the Cyanobacterial Extracellular Polysaccharide

The self-organization behavior of an extracellular polysaccharide (sacran) extracted from the cyanobacterium Aphanothece sacrum in response to lanthanoid ion adsorption was investigated. Consequently, cryogenic TEM images revealed that sacran could be cross-linked by Nd(3+) trivalent ions and formed a fibrous nanostructural network containing water. Furthermore, sacran adsorbed trivalent metal ions at a 3:1 ratio, which was the theoretical ionic adsorption and showed more efficient adsorption than alginate based on electric conductivity titration. The critical gelation concentrations, Cg, where sacran formed tough gels upon metal ion binding were estimated. The Cg for trivalent metal ions was lower than that for divalent ions, and the Cg for lanthanoid ions was particularly low at 10(-3) to 10(-4) M, changing every four elemental numbers. The extracellular matrix of Aphanothece sacrum, sacran, may adsorb metal ions to create fibrous nanostructures that reinforce the jelly matrix.

Evaluation of an Edible Blue-Green Alga,Aphanothece sacrum, for Its Inhibitory Effect on Replication of Herpes Simplex Virus Type 2 and Influenza Virus Type A

A hot-water extract of Aphanothece sacrum, an edible aquacultured blue-green alga, was found to show a remarkable inhibitory effect on the replication of enveloped viruses including herpes simplex virus type 2 (HSV-2) and influenza virus type A (IFV-A, H1N1) in vitro. The main active components were suggested to be sulfated polysaccharides in non-dialyzable portion (ASWPH). ASWPH was found to inhibit the viral adsorption to the receptor of the host cells involved in the replication process of HSV-2 and IFV-A. In addition, while the penetration stage of HSV-2 was also significantly suppressed with ASWPH, no such effect was observed in the replication of IFV-A. These results suggest that ASWPH might be useful in the prevention of infectious diseases caused by HSV-2 as well as IFV-A.

Cyanobacterial Polysaccharide Gels with Efficient Rare-Earth-Metal Sorption

The cyanobacterial polysaccharide sacran, which contains carboxylate and sulfate groups, was extracted from Aphanothece sacrum , and the metal sorption behavior of sacran was investigated. Heterogels, where the sacran chains were trapped by polyvinyl alcohol networks, were prepared and immersed in NdCl3 solutions to shrink and cloud due to Nd binding. These heterogels had the ability to sorb excessive amounts of Nd ions, more than the stoichiometric ratio of 1:3 (sacran anion/Nd). Furthermore, the sacran-containing gels sorbed Nd ions under highly acidic conditions below pH 2 more efficiently than alginate-containing gels. We speculated that the strong Nd condensation effect of the sulfate groups in sacran under the acidic conditions may enhance the Nd sorption to the carboxylate groups.

Cyanobacterial Megamolecule Sacran Efficiently Forms LC Gels with Very Heavy Metal Ions

We extracted the megamolecular polysaccharide sacran, which contains carboxylate and sulfate groups, from the jellylike extracellular matrix (ECM) of the cyanobacterium Aphanothece sacrum, which has mineral adsorption bioactivity. We investigated the gelation properties of sacran binding with various heavy metal ions. The sacran chain adsorbed heavier metal ions such as indium, rare earth metals, and lead ions more efficiently to form gel beads. In addition, trivalent metal ions adsorbed onto the sacran chains more efficiently than did divalent ions. The investigation of the metal ion binding ratio on sacran chains demonstrated that sacran adsorbed gadolinium trivalent ions more efficiently than indium trivalent ions. Gel bead formation may be closely correlated to the liquid-crystalline organization of sacran.