Comparative Analysis of the Functional Properties of Films Based on Carrageenans,Chitosan, and Their Polyelectrolyte Complexes

The influence of the structural features of carrageenan on the functional properties of the films was studied. The carrageenans and chitosan films, as well as three-layer films containing a polyelectrolyte complex (PEC) of the two, were prepared. The X-ray diffractograms of carrageenan films reflected its amorphous structure, whereas chitosan and three-layer films were characterized by strong reflection in the regions of 20° and 15° angles, respectively. The SEM of the cross-sectional morphology showed dense packing of the chitosan film, as well as the layer-by-layer structure of different densities for the PEC. Among the tested samples, κ/β-carrageenan and chitosan films showed the highest tensile strength and maximum elongation. Films containing the drug substance echinochrome were obtained. Mucoadhesive properties were assessed as the ability of the films to swell on the mucous tissue and their erosion after contact with the mucosa. All studied films exhibited mucoadhesive properties. All studied films exhibited mucoadhesive properties which depended on the carrageenans structure. Multilayer films are stronger than single-layer carrageenan films due to PEC formation. The resulting puncture strength of the obtained films was comparable to that of commercial samples described in the literature.     

Inhibition of SARS-CoV-2 Virus Entry by the Crude Polysaccharides of Seaweeds and Abalone Viscera In Vitro

Much attention is being devoted to the potential of marine sulfated polysaccharides as antiviral agents in preventing COVID-19. In this study, sulfated fucoidan and crude polysaccharides, extracted from six seaweed species (Undaria pinnatifida sporophyll, Laminaria japonica, Hizikia fusiforme, Sargassum horneri, Codium fragile, Porphyra tenera) and Haliotis discus hannai (abalone viscera), were screened for their inhibitory activity against SARS-CoV-2 virus entry. Most of them showed significant antiviral activities at an IC50 of 12~289 μg/mL against SARS-CoV-2 pseudovirus in HEK293/ACE2, except for P. tenera (IC50 > 1000 μg/mL). The crude polysaccharide of S. horneri showed the strongest antiviral activity, with an IC50 of 12 μg/mL, to prevent COVID-19 entry, and abalone viscera and H. fusiforme could also inhibit SARS-CoV-2 infection with an IC50 of 33 μg/mL and 47 μg/mL, respectively. The common properties of these crude polysaccharides, which have strong antiviral activity, are high molecular weight (>800 kDa), high total carbohydrate (62.7~99.1%), high fucose content (37.3~66.2%), and highly branched polysaccharides. These results indicated that the crude polysaccharides from seaweeds and abalone viscera can effectively inhibit SARS-CoV-2 entry.     

Efficacy of Posidonia oceanica Extract against Inflammatory Pain: In Vivo Studies in Mice

Posidonia oceanica (L.) Delile is traditionally used for its beneficial properties. Recently, promising antioxidant and anti-inflammatory biological properties emerged through studying the in vitro activity of the ethanolic leaves extract (POE). The present study aims to investigate the anti-inflammatory and analgesic role of POE in mice. Inflammatory pain was modeled in CD-1 mice by the intraplantar injection of carrageenan, interleukin IL-1β and formalin. Pain threshold was measured by von Frey and paw pressure tests. Nociceptive pain was studied by the hot-plate test. POE (10–100 mg kg⁻¹) was administered per os. The paw soft tissue of carrageenan-treated animals was analyzed to measure anti-inflammatory and antioxidant effects. POE exerted a dose-dependent, acute anti-inflammatory effect able to counteract carrageenan-induced pain and paw oedema. Similar anti-hyperalgesic and anti-allodynic results were obtained when inflammation was induced by IL-1β. In the formalin test, the pre-treatment with POE significantly reduced the nocifensive behavior. Moreover, POE was able to evoke an analgesic effect in naïve animals. Ex vivo, POE reduced the myeloperoxidase activity as well as TNF-α and IL-1β levels; further antioxidant properties were highlighted as a reduction in NO concentration. POE is the candidate for a new valid strategy against inflammation and pain.     

Ultrasound-Assisted Water Extraction of Mastocarpus stellatus Carrageenan with Adequate Mechanical and Antiproliferative Properties

Ultrasound-assisted water extraction was optimized to recover gelling biopolymers and antioxidant compounds from Mastocarpus stellatus. A set of experiments following a Box–Behnken design was proposed to study the influence of extraction time, solid liquid ratio, and ultrasound amplitude on the yield, sulfate content, and thermo-rheological properties (viscoelasticity and gelling temperature) of the carrageenan fraction, as well as the composition (protein and phenolic content) and antiradical capacity of the soluble extracts. Operating at 80 °C and 80 kHz, the models predicted a compromise optimum extraction conditions at ~35 min, solid liquid ratio of ~2 g/100 g, and ultrasound amplitude of ~79%. Under these conditions, 40.3% carrageenan yield was attained and this product presented 46% sulfate and good mechanical properties, a viscoelastic modulus of 741.4 Pa, with the lowest gelling temperatures of 39.4 °C. The carrageenans also exhibited promising antiproliferative properties on selected human cancer cellular lines, A-549, A-2780, HeLa 229, and HT-29 with EC₅₀ under 51.9 μg/mL. The dried soluble extract contained 20.4 mg protein/g, 11.3 mg gallic acid eq/g, and the antiradical potency was equivalent to 59 mg Trolox/g.     

Extraction of Fatty Acids and Phenolics from Mastocarpus stellatus Using Pressurized Green Solvents

Polyunsaturated fatty acids are well known for their protective properties in relation to different skin diseases. Although seaweeds possess a low lipid fraction, they could act as an alternative renewable source of polyunsaturated fatty acids whenever other valuable seaweed components are also valorized. In this study, a biorefinery process using Mastocarpus stellatus as a model seaweed was proposed. The process started with the supercritical carbon dioxide extraction of the lipid and phenolic fractions. The influence of pressure during extraction with pure supercritical CO₂ was studied while operating at a selected temperature and solvent flow rate. Kinetic data obtained during the ethanol-modified supercritical CO₂ extraction were fitted to the spline model. Sequential processing was proposed with (i) pure CO₂ to obtain a product with 30% PUFA content and ω-3:ω-6 ratio 1:1, (ii) ethanol-modified CO₂ to extract phenolics, and (iii) microwave-assisted subcritical water extraction operating under previously optimized conditions for the extraction of phenolics, carrageenan and protein fractions. The composition of the supercritical extracts showed potential for use in both dietary and topical applications in skin care products. The remaining solids are suitable for the extraction of other valuable fractions.     

Flexibilide Obtained from Cultured Soft Coral Has Anti-Neuroinflammatory and Analgesic Effects through the Upregulation of Spinal Transforming Growth Factor-β1 in Neuropathic Rats

Chronic neuroinflammation plays an important role in the development and maintenance of neuropathic pain. The compound flexibilide, which can be obtained from cultured soft coral, possesses anti-inflammatory and analgesic effects in the rat carrageenan peripheral inflammation model. In the present study, we investigated the antinociceptive properties of flexibilide in the rat chronic constriction injury (CCI) model of neuropathic pain. First, we found that a single intrathecal (i.t.) administration of flexibilide significantly attenuated CCI-induced thermal hyperalgesia at 14 days after surgery. Second, i.t. administration of 10-μg flexibilide twice daily was able to prevent the development of thermal hyperalgesia and weight-bearing deficits in CCI rats. Third, i.t. flexibilide significantly inhibited CCI-induced activation of microglia and astrocytes, as well as the upregulated proinflammatory enzyme, inducible nitric oxide synthase, in the ipsilateral spinal dorsal horn. Furthermore, flexibilide attenuated the CCI-induced downregulation of spinal transforming growth factor-β1 (TGF-β1) at 14 days after surgery. Finally, i.t. SB431542, a selective inhibitor of TGF-β type I receptor, blocked the analgesic effects of flexibilide in CCI rats. Our results suggest that flexibilide may serve as a therapeutic agent for neuropathic pain. In addition, spinal TGF-β1 may be involved in the anti-neuroinflammatory and analgesic effects of flexibilide.     

Griffithsin and Carrageenan Combination Results in Antiviral Synergy against SARS-CoV-1 and 2 in a Pseudoviral Model

Over 182 million confirmed cases of COVID-19 and more than 4 million deaths have been reported to date around the world. It is essential to identify broad-spectrum antiviral agents that may prevent or treat infections by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but also by other coronaviruses that may jump the species barrier in the future. We evaluated the antiviral selectivity of griffithsin and sulfated and non-sulfated polysaccharides against SARS-CoV-1 and SARS-CoV-2 using a cytotoxicity assay and a cell-based pseudoviral model. The half-maximal cytotoxic concentration (CC₅₀) and half-maximal effective concentration (EC₅₀) were determined for each compound, using a dose-response-inhibition analysis on GraphPad Prism v9.0.2 software (San Diego, CA, USA). The therapeutic index (TI = CC₅₀/EC₅₀) was calculated for each compound. The potential synergistic, additive, or antagonistic effect of different compound combinations was determined by CalcuSyn v1 software (Biosoft, Cambridge, UK), which estimated the combination index (CI) values. Iota and lambda carrageenan showed the most potent antiviral activity (EC₅₀ between 3.2 and 7.5 µg/mL). Carrageenan and griffithsin combinations exhibited synergistic activity (EC₅₀ between 0.2 and 3.8 µg/mL; combination index <1), including against recent SARS-CoV-2 mutations. The griffithsin and carrageenan combination is a promising candidate to prevent or treat infections by SARS-CoV-1 and SARS-CoV-2.     

Preparation and Characterization of κ-Carrageenan Modified with Maleic Anhydride and Its Application in Films

In this work, the physicochemical properties of maleic anhydride (MAH)-modified κ-carrageenan (κCar) (MC) were characterized and compared with those of native κ-carrageenan (NC). The Fourier transform infrared spectrum of MC exhibited that κCar was successfully modified. Thermogravimetric analysis indicated that the thermal stability of MC was decreased. When the degree of substitution was 0.032, MC exhibited a low gel strength (759 g/cm²), gelling temperature (33.3 °C), and dehydration rate (60.3%). Given the excellent film-forming ability of κCar, MC films were then prepared and were found to have better mechanical and barrier properties (UV and water) than NC films. With regard to optical properties, MC films could completely absorb UV light in the range of 200–236 nm. The water contact angle of MC films was higher than that of NC films. Moreover, the elongation at break increased from 26.9% to 163%. These physicochemical property changes imply that MC can be employed in polysaccharide-based films.     

Interactions of Globular and Ribbon [γ4E]GID with α4β2 Neuronal Nicotinic Acetylcholine Receptor

The α4β2 nAChR is implicated in a range of diseases and disorders including nicotine addiction, epilepsy and Parkinson’s and Alzheimer’s diseases. Designing α4β2 nAChR selective inhibitors could help define the role of the α4β2 nAChR in such disease states. In this study, we aimed to modify globular and ribbon α-conotoxin GID to selectively target the α4β2 nAChR through competitive inhibition of the α4(+)β2(−) or α4(+)α4(−) interfaces. The binding modes of the globular α-conotoxin [γ4E]GID with rat α3β2, α4β2 and α7 nAChRs were deduced using computational methods and were validated using published experimental data. The binding mode of globular [γ4E]GID at α4β2 nAChR can explain the experimental mutagenesis data, suggesting that it could be used to design GID variants. The predicted mutational energy results showed that globular [γ4E]GID is optimal for binding to α4β2 nAChR and its activity could not likely be further improved through amino-acid substitutions. The binding mode of ribbon GID with the (α4)₃(β2)₂ nAChR was deduced using the information from the cryo-electron structure of (α4)₃(β2)₂ nAChR and the binding mode of ribbon AuIB. The program FoldX predicted the mutational energies of ribbon [γ4E]GID at the α4(+)α4(−) interface, and several ribbon[γ4E]GID mutants were suggested to have desirable properties to inhibit (α4)₃(β2)₂ nAChR.     

Antarctic Thraustochytrids as Sources of Carotenoids and High-Value Fatty Acids

Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and carotenoids are needed as human dietary supplements and are essential components in commercial feeds for the production of aquacultured seafood. Microorganisms such as thraustochytrids are potential natural sources of these compounds. This research reports on the lipid and carotenoid production capacity of thraustochytrids that were isolated from coastal waters of Antarctica. Of the 22 isolates, 21 produced lipids containing EPA+DHA, and the amount of these fatty acids exceeded 20% of the total fatty acids in 12 isolates. Ten isolates were shown to produce carotenoids (27.4–63.9 μg/g dry biomass). The isolate RT2316-16, identified as Thraustochytrium sp., was the best producer of biomass (7.2 g/L in five days) rich in carotenoids (63.9 μg/g) and, therefore, became the focus of this investigation. The main carotenoids in RT2316-16 were β-carotene and canthaxanthin. The content of EPA+DHA in the total lipids (34 ± 3% w/w in dry biomass) depended on the stage of growth of RT2316-16. Lipid and carotenoid content of the biomass and its concentration could be enhanced by modifying the composition of the culture medium. The estimated genome size of RT2316-16 was 44 Mb. Of the 5656 genes predicted from the genome, 4559 were annotated. These included genes of most of the enzymes in the elongation and desaturation pathway of synthesis of ω-3 polyunsaturated fatty acids. Carotenoid precursors in RT2316-16 were synthesized through the mevalonate pathway. A β-carotene synthase gene, with a different domain organization compared to the gene in other thraustochytrids, explained the carotenoid profile of RT2316-16.     

The Nemertine Toxin Anabaseine and Its Derivative DMXBA (GTS-21): Chemical and Pharmacological Properties

Nemertines are a phylum of carnivorous marine worms that possess a variety of alkaloidal, peptidic or proteinaceous toxins that serve as chemical defenses against potential predators. The hoplonemertines additionally envenomate their prey with a mixture of proboscis alkaloids delivered with the help of a calcareous stylet that punctures the skin of the victim. Anabaseine, the first of these alkaloids to be identified, stimulates a wide variety of animal nicotinic acetylcholine receptors (AChRs), especially the neuromuscular [e.g., α1₂β1γδ (embryogenic) or α1₂β1γɛ (adult)] and α7 AChRs that are inhibited by the snake peptide α-bungarotoxin. A synthetic derivative, 3-(2,4-Dimethoxybenzylidene)-Anabaseine (DMXBA; also called GTS-21), improves memory in experimental animals and humans and is currently in clinical trials to determine whether it can ameliorate cognitive problems associated with schizophrenia. Here we summarize present knowledge concerning the chemistry and mechanisms of action of these two substances (anabaseine and DMXBA) on AChRs, especially those found in the mammalian brain.     

Neuritogenic and Neuroprotective Effects of Polar Steroids from the Far East Starfishes Patiria pectinifera and Distolasterias nipon

The neuritogenic and neuroprotective activities of six starfish polar steroids, asterosaponin Р₁, (25S)-5α-cholestane-3β,4β,6α,7α,8,15α,16β,26-octaol, and (25S)-5α-cholestane-3β,6α,7α,8,15α,16β,26-heptaol (1–3) from the starfish Patiria pectinifera and distolasterosides D₁–D₃ (4–6) from the starfish Distolasterias nipon were analyzed using the mouse neuroblastoma (NB) C-1300 cell line and an organotypic rat hippocampal slice culture (OHSC). All of these compounds enhanced neurite outgrowth in NB cells. Dose-dependent responses to compounds 1–3 were observed within the concentration range of 10–100 nM, and dose-dependent responses to glycosides 4–6 were observed at concentrations of 1–50 nM. All the tested substances exhibited notable synergistic effects with trace amounts of nerve growth factor (NGF, 1 ng/mL) or brain-derived neurotrophic factor (BDNF, 0.1 ng/mL). Using NB cells and OHSCs, it was shown for the first time that starfish steroids 1–6 act as neuroprotectors against oxygen-glucose deprivation (OGD) by increasing the number of surviving cells. Altogether, these results suggest that neurotrophin-like neuritogenic and neuroprotective activities are most likely common properties of starfish polyhydroxysteroids and the related glycosides, although the magnitude of the effect depended on the particular compound structure.     

Nigrodiquinone A,a Hydroanthraquinone Dimer Containing a Rare C-9–C-7′ Linkage from a Zoanthid-Derived Nigrospora sp. Fungus

One new hydroanthraquinone dimer with a rare C-9–C-7′ linkage, nigrodiquinone A (1), and four known anthraquinone monomers 2–5, were isolated from a fungus Nigrospora sp. obtained from the zoanthid Palythoa haddoni collected in the South China Sea. The structure of 1 was established through extensive NMR spectroscopy, and the absolute configuration was elucidated by comparing computed electronic circular dichroism (ECD) and optical rotations (OR) with experimental results. All the compounds were evaluated for antiviral activity, and 1 was also evaluated for antibacterial activity. Compound 4 displayed mild antiviral activity against coxsackie virus (Cox-B3) with the IC₅₀ value of 93.7 μM, and 5 showed an IC₅₀ value of 74.0 μM against respiratory syncytial virus (RSV).     

Linagliptin Protects Human SH-SY5Y Neuroblastoma Cells against Amyloid-β Cytotoxicity via the Activation of Wnt1 and Suppression of IL-6 Release

Background:Alzheimer’s disease is one of the neurodegenerative disorders typified by the aggregate of Aβ and phosphorylated tau protein. Oxidative stress and neuroinflammation, because of Aβ peptides, are strongly involved in the pathophysiology of AD. Linagliptin shows neuroprotective properties against AD pathological processes through alleviation of neural inflammation and AMPK activation. Methods:We assessed the benefits of linagliptin pretreatment (at 10, 20, and 50 nM concentrations), against Aβ1-42 toxicity (20 μM) in SH-SY5Y cells. The concentrations of secreted cytokines, such as TNF-α, IL-6, and IL-1β, and signaling proteins, including pCREB, Wnt1, and PKCε, were quantified by ELISA. Results:We observed that Aβ led to cellular inflammation, which was assessed by measuring inflammatory cytokines (TNF-α, IL-1β, and IL-6). Moreover, Aβ1-42 treatment impaired pCREB, PKCε, and Wnt1 signaling in human SH-SY5Y neuroblastoma cells. Addition of Linagliptin significantly reduced IL-6 levels in the lysates of cells, treated with Aβ1-42. Furthermore, linagliptin prevented the downregulation of Wnt1 in Aβ1-42-treated cells exposed. Conclusion: The current findings reveal that linagliptin alleviates Aβ1-42-induced inflammation in SH-SY5Y cells, probably through the suppression of IL-6 release, and some of its benefits are mediated through the activation of the Wnt1 signaling pathway. Key Words: Alzheimer disease, Interleukin-6, Linagliptin, Wnt1 protein     

A Possible Mechanism of Action of the Chemopreventive Effects of Sarcotriol on Skin Tumor Development in CD-1 Mice

Sarcophine derivatives have been suggested to be chemopreventive in nature. One of its derivatives, Sarcotriol (ST), was investigated to study the skin cancer chemopreventive effects in female CD-1 mice. Three groups (control, promotion, initiation) of 30 female CD-1 mice each were taken. Carcinogenesis was initiated with 7, 12- dimethylbenz (a) anthracene (DMBA) and promoted with 12-O-tetradecanoylphorbol-13- acetate (TPA). One hour before treating with DMBA (200 nmol/100 μl acetone), control and promotion groups were treated with acetone (100 μl) and initiation group with ST (30μg/100μl of acetone). Beginning one week after initiation with DMBA, control and initiation groups were treated with acetone and promotion group with ST (30μg/100μl of acetone), one hour before treating with TPA (5 nmol/100 μl acetone). This was carried out twice a week for the next 20 weeks. The effects of ST on ³H-thymidine incorporation in epidermal DNA, the possible role of apoptotic proteins and COX-2 involved in the prevention of skin tumor development of CD-1 mice were investigated. Tumor incidence and multiplicity was found to be 100%, 73%, 100% and 8.2, 4.8, 9.7 in control, promotion and initiation groups respectively. ST treatment resulted in a significant (P < 0.05) inhibition in the incorporation of ³H-thymidine in epidermal DNA. The promotion group showed higher levels of caspase-3, -8 and –9 compared to the control. COX-2 expression was significantly lower (P < 0.05) in the promotion group as compared to the control. No significant difference in caspase-3, -8, -9 and COX-2 levels were observed in the initiation group compared to control. Together, this study confirms the chemopreventive effects of ST, and for the first time identifies the stage of carcinogenesis at which ST exerts its chemopreventive effect, and elucidates the mechanism possibly by inducing apoptosis and decreasing the COX-2 levels, contributing to its overall cancer chemopreventive effects in the mouse skin cancer model.     

Anti-Dengue Virus Constituents from Formosan Zoanthid Palythoa mutuki

A new marine ecdysteroid with an α-hydroxy group attaching at C-4 instead of attaching at C-2 and C-3, named palythone A (1), together with eight known compounds (2–9) were obtained from the ethanolic extract of the Formosan zoanthid Palythoa mutuki. The structures of those compounds were mainly determined by NMR spectroscopic data analyses. The absolute configuration of 1 was further confirmed by comparing experimental and calculated circular dichroism (CD) spectra. Anti-dengue virus 2 activity and cytotoxicity of five isolated compounds were evaluated using virus infectious system and [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assays, respectively. As a result, peridinin (9) exhibited strong antiviral activity (IC₅₀ = 4.50 ± 0.46 μg/mL), which is better than that of the positive control, 2′CMC. It is the first carotene-like substance possessing anti-dengue virus activity. In addition, the structural diversity and bioactivity of the isolates were compared by using a ChemGPS–NP computational analysis. The ChemGPS–NP data suggested natural products with anti-dengue virus activity locate closely in the chemical space.     

The Glycolytic Enzymes Activity in the Midgut of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) adult and their Seasonal Changes

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is an important pest of maize. The diet of the D. virgifera imago is rich in starch and other polysaccharides present in cereals such as maize. Therefore, knowledge about enzymes involved in digestion of such specific food of this pest seems to be important. The paper shows, for the first time, the activities of main glycolytic enzymes in the midgut of D. virgifera imago: endoglycosidases (α-amylase, cellulase, chitinase, licheninase, laminarinase); exoglycosidases (α- and β-glucosidases, α- and β-galactosidases) and disaccharidases (maltase, isomaltase, sucrase, trehalase, lactase, and cellobiase). Activities of α-amylase, α-glucosidase, and maltase were the highest among assayed endoglycosidases, exoglycosidases, and disaccharidases, respectively. This indicates that in the midgut of D. virgifera imago α-amylase, α-glucosidase and maltase are important enzymes in starch hydrolysis and products of its digestion. These results lead to conclusion that inhibition of most active glycolytic enzymes of D. virgifera imago may be another promising method for chemical control of this pest of maize.     

Residues Responsible for the Selectivity of α-Conotoxins for Ac-AChBP or nAChRs

Nicotinic acetylcholine receptors (nAChRs) are targets for developing new drugs to treat severe pain, nicotine addiction, Alzheimer disease, epilepsy, etc. α-Conotoxins are biologically and chemically diverse. With 12–19 residues and two disulfides, they can be specifically selected for different nAChRs. Acetylcholine-binding proteins from Aplysia californica (Ac-AChBP) are homologous to the ligand-binding domains of nAChRs and pharmacologically similar. X-ray structures of the α-conotoxin in complex with Ac-AChBP in addition to computer modeling have helped to determine the binding site of the important residues of α-conotoxin and its affinity for nAChR subtypes. Here, we present the various α-conotoxin residues that are selective for Ac-AChBP or nAChRs by comparing the structures of α-conotoxins in complex with Ac-AChBP and by modeling α-conotoxins in complex with nAChRs. The knowledge of these binding sites will assist in the discovery and design of more potent and selective α-conotoxins as drug leads.     

Fucoidans as Potential Inhibitors of HIV-1

The antiviral activity of different structure fucoidans (α-l-fucans and galactofucans) was studied using two model viral systems based on a lentiviral vectors and a replication competent Moloney murine leukemia virus (Mo-MuLV). It was found that investigated fucoidans have no cytotoxic effects on Jurkat and SC-1cell at the concentration range of 0.001–100 µg/mL. Fucoidans with different efficiency suppressed transduction of Jurkat cell line by pseudo-HIV-1 particles carrying the envelope protein of HIV-1 and infection of SC-1 cells by Mo-MuLV. According to our data, all natural fucoidans can be considered as potential anti-HIV agents regardless of their carbohydrate backbone and degree of sulfating, since their activity is shown at low concentrations (0.001–0.05 µg/mL). High molecular weight fucoidans isolated from Saccharina cichorioides (1.3-α-l-fucan), and S. japonica (galactofucan) were the most effective inhibitors.     

Fish Synucleins: An Update

Synucleins (syns) are a family of proteins involved in several human neurodegenerative diseases and tumors. Since the first syn discovery in the brain of the electric ray Torpedo californica, members of the same family have been identified in all vertebrates and comparative studies have indicated that syn proteins are evolutionary conserved. No counterparts of syns were found in invertebrates suggesting that they are vertebrate-specific proteins. Molecular studies showed that the number of syn members varies among vertebrates. Three genes encode for α-, β- and γ-syn in mammals and birds. However, a variable number of syn genes and encoded proteins is expressed or predicted in fish depending on the species. Among biologically verified sequences, four syn genes were identified in fugu, encoding for α, β and two γ (γ1 and γ2) isoforms, whereas only three genes are expressed in zebrafish, which lacks α-syn gene. The list of “non verified” sequences is much longer and is often found in sequence databases. In this review we provide an overview of published papers and known syn sequences in agnathans and fish that are likely to impact future studies in this field. Indeed, fish models may play a key role in elucidating some of the molecular mechanisms involved in physiological and pathological functions of syn proteins.