Antiviral Activities of Marine Pseudomonas Polysaccharides and Their Oversulfated Derivatives

A marine Pseudomonas species WAK-1 strain simultaneously produces extracellular glycosaminoglycan and sulfated polysaccharide. Among the antiviral activities tested for these polysaccharides, the latter showed anti-HSV-1 activity in RPMI 8226 cells (50% effective concentration is 1.4 μg/ml). Oversulfated derivatives of these polysaccharides prepared by dicyclohexylcarbodiimide-mediated reaction for both polysaccharides showed antiviral activities against influenza virus type A (for glycosaminoglycan, 50% effective concentration is 11.0 μg/ml; for another, 2.9 μg/ml). Glycosaminoglycan, sulfated polysaccharide, and their chemically synthesized oversulfated derivatives did not show antiviral activities against influenza virus type B and human immunodeficiency virus type 1. No cytotoxicity of these products was noted against host cells at the 50% cytotoxic concentration of 100 μg/ml, except that naturally occurring sulfated polysaccharide had 50% cytotoxicity against MT-4 cells at 8–21 μg/ml. Received May 1, 1998; accepted July 24, 1998.     

In Vitro Anti-influenza Virus Activities of Sulfated Polysaccharide Fractions from Gracilaria lemaneiformis

In this paper, in vitro anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were investigated. Cytotoxicities and antiviral activities of Gracilaria lemaneiformis polysaccharides (PGL), Gracilaria lemaneiformis polysaccharide fraction-1 (GL-1), Gracilaria lemaneiformis polysaccharide fraction-2 (GL-2) and Gracilaria lemaneiformis polysaccharide fraction-3 (GL-3) were studied by the Methyl thiazolyl tetrazolium (MTT) method, and the inhibitory effect against Human influenza virus H1-364 induced cytopathic effect (CPE) on MDCK cells were observed by the CPE method. In addition, the antiviral mechanism of PGL was explored by Plaque forming unit (PFU), MTT and CPE methods. The results showed: i) Cytotoxicities were not significantly revealed, and H1-364 induced CPE was also reduced treated with sulfated polysaccharide fractions from Gracilaria lemaneiformis; ii) Antiviral activities were associated with the mass percentage content of sulfate groups in polysaccharide fractions, which was about 13%, in polysaccharides (PGL and GL-2) both of which exhibited higher antiviral activity; iii) A potential antiviral mechanism to explain these observations is that viral adsorption and replication on host cells were inhibited by sulfated polysaccharides from Gracilaria lemaneiformis. In conclusion, Anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were revealed, and the antiviral activities were associated with content of sulfate groups in polysaccharide fractions.     

In vitro anti-influenza virus activities of sulfated polysaccharide fractions from <Emphasis Type="Italic">Gracilaria lemaneiformis</Emphasis>

In this paper, in vitro anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were investigated. Cytotoxicities and antiviral activities of Gracilaria lemaneiformis polysaccharides (PGL), Gracilaria lemaneiformis polysaccharide fraction-1 (GL-1), Gracilaria lemaneiformis polysaccharide fraction-2 (GL-2) and Gracilaria lemaneiformis polysaccharide fraction-3 (GL-3) were studied by the Methyl thiazolyl tetrazolium (MTT) method, and the inhibitory effect against Human influenza virus H1-364 induced cytopathic effect (CPE) on MDCK cells were observed by the CPE method. In addition, the antiviral mechanism of PGL was explored by Plaque forming unit (PFU), MTT and CPE methods. The results showed: i) Cytotoxicities were not significantly revealed, and H1-364 induced CPE was also reduced treated with sulfated polysaccharide fractions from Gracilaria lemaneiformis; ii) Antiviral activities were associated with the mass percentage content of sulfate groups in polysaccharide fractions, which was about 13%, in polysaccharides (PGL and GL-2) both of which exhibited higher antiviral activity; iii) A potential antiviral mechanism to explain these observations is that viral adsorption and replication on host cells were inhibited by sulfated polysaccharides from Gracilaria lemaneiformis. In conclusion, Anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were revealed, and the antiviral activities were associated with content of sulfate groups in polysaccharide fractions.     

Antiviral activity of aqueous extracts and polysaccharide fractions from mycelium and fruit bodies of higher fungi

Sixty preparations of basidiomycetes (Ganoderma, Lentinus, Pleurotus, Laetiporus, Polyporus, Inonotus, Flammulina, Grifola, Trametes) were investigated with respect to their toxicity for Vero cells and antiviral activity. The antiviral activity was estimated with the use of the West Nile virus and type 2 Herpes simplex. It was shown that 11 preparations of Ganoderma, Lentinus and Pleurotus completely inhibited the infective activity in doses not lower than 1000 TCD50 (the West Nile virus) and 100 PPU (type 2 Herpes simplex). The antiviral activity of the preparations was likely due to the content of polysaccharides or their derivatives in the composition. It increased with increasing of the quantity of the total polysaccharide fraction or its concentration.     

Structures and anti-HSV-2 activities of neutral polysaccharides from an edible plant, Basella rubra L

Four neutral polysaccharides (BRN-1, BRN-2, BRN-3 and BRN-4) were isolated from the hot water extract of the aerial part of Basella rubra L. They were found to consist of a large amount of d-galactose (81.0-92.4%) and small amounts of l-arabinose (5.4-7.8%), d-glucose (2.2-11.0%) and mannose (∼2.9%). Linkage analysis revealed that all these neutral polysaccharides might be arabinogalactan type I polysaccharides in different molecular weight and chain length. Among them, only BRN-3 showed antiviral activity against herpes simplex virus type 2 (HSV-2) with 50% inhibitory concentration of 55 μg/mL without showing the cytotoxicity up to 2300 μg/mL. Furthermore, the main antiviral target of BRN-3 was shown to be the inhibition of virus adsorption to host cells. This is the first report on the neutral polysaccharide with anti-HSV-2 activity obtained from B. rubra L.     

Antiviral compounds in extracts of Korean seaweeds: Evidence for multiple activities

Extracts of 13 Korean seaweeds, previously shown to contain antiviral activity, were investigated in more detail in order to learn the nature of the antiviral compounds and their mechanisms of action. One extract, from Codium fragile, was active against all three test viruses (herpes simplex, HSV; Sindbis, SINV; polio), whereas the others were more selective. Thus four species, Enteromorpha linza, Colpomenia bullosa, Scytosiphon lomentaria, and Undaria pinnatifida, were active against HSV and SINV, but not poliovirus. The other eight were active against either HSV or SINV. In all cases there was evidence for photosensitizers, since the antiviral activities required or were enhanced substantially by light. In general UVA (long wave ultraviolet) was much more effective than visible light in promoting activity, although the extract of Sargassum sagamianum could be activated equally by either. In experiments to determine the site of action of these antiviral extracts, the predominant activity was virucidal (i.e. direct inactivation of virus particles), rather than inhibition of virus replication, although Sargassum sagamianum also could protect cells against subsequent virus infection. These results imply that different antiviral compounds are present among the extracts, and furthermore the activities cannot be explained in terms of common ingredients such as polysaccharides or tannins. We suggest that seaweeds may be a source of potentially useful and interesting antiviral compounds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Revelation of Antiviral Activities by Artificial Sulfation of a Glycosaminoglycan from a Marine Pseudomonas

Sulfated derivatives of a glycosaminoglycan containing l-glutamic acid produced by a marine Pseudomonas species, No. 42 strain, were prepared by the method of dicyclohexyl-carbodiimide-mediated reaction. Both low and high degrees of sulfation of the polysaccharides (products A1 and A2, respectively) were investigated for their antiviral activities against influenza virus type A (FluV-A) and B (FluV-B) in MDCK cells. Both preparations showed antiviral activity against FluV-A at the 50% antiviral effective concentration of 17.3 and 5.2 μg/ml, respectively, whereas they had no antiviral activity against FluV-B. No cytotoxicity of either product was noted against MDCK cells at the 50% cytotoxic concentration of 100 μg/ml. Received April 4, 1998; accepted July 24, 1998.     

Structural analysis and antiviral activity of a sulfated galactan from the red seaweed Schizymenia binderi (Gigartinales, Rhodophyta)

Aqueous extraction of gametophytic Schizymenia binderi afforded a polysaccharide composed of galactose and sulfate groups in a molar ratio of 1.0:0.89 together with uronic acids (6.8 wt%) and minor amounts of other neutral sugars. Alkali-treatment of the polysaccharide afforded a polysaccharide devoid of 3,6-anhydrogalactose. 13C NMR spectroscopy of the desulfated alkali-treated polysaccharide showed a backbone structure of alternating 3-linked beta-D-galactopyranosyl and 4-linked alpha-galactopyranosyl units that are predominantly of the D-configuration and partly of the L-configuration. Methylation, ethylation and NMR spectroscopic studies of the alkali-treated polysaccharide indicated that the sulfate groups are located mainly at positions O-2 of 3-linked beta-D-galactopyranosyl residue and at position O-3 of 4-linked-alpha-galactopyranosyl residues, the latter is partially glycosylated at position O-2. The sulfated galactan from S. binderi exhibited highly selective antiviral activity against Herpes simplex virus types 1 and 2, with selectivity indices (ratio cytotoxicity/antiviral activity) >1000 for all assayed virus strains. This compound was shown to interfere with the initial adsorption of viruses to cells.     

Antiviral activity in urine is attributable to ammonium salts

Urine exhibits antiviral activity in tissue culture against a number of viruses. We have characterized that antiviral activity in comparison with a number of antiviral substances which are known to be present in body fluids. We show here that the antiviral activity in urine cannot be due to the presence of contact-blocking virus inhibitor (CVI), or interferon. The findings support the conclusion that most of the antiviral activity in urine is qualitatively and quantitavely attributable to its content of ammonium salts.     

Characterization of the Antiviral Activity for Influenza Viruses M1 Zinc Finger Peptides

We sought to investigate the cellular uptake and antiviral activity for the M1 zinc finger peptides derived from influenza A and influenza B viruses in vitro. No cellular uptake was detected by fluorescent microscopy for the synthetic zinc finger peptides. When flanked to a cell permeable peptide Tp10, the zinc finger recombinant proteins were efficiently internalized by MDCK cells. However, no antiviral activity was detected against homologous or heterologous virus infections for the synthetic peptides or the Tp10-flanked recombinant proteins, regardless treated with or without Zn²⁺. Nevertheless, MDCK cell constitutively expressing the M1 zinc finger peptides in cell nuclei potently inhibited replication of homologous, but not heterologous influenza viruses. Adenoviral vector delivered M1 zinc finger peptides also exhibited potent antiviral activity against homologous viruses challenge. Transduction at 100 PFU dose of recombinant adenovirus efficiently protected 99% of the cells from 100 TCID₅₀ of different virus infections for both peptides. These results brought new insight to the antiviral researches against influenza virus infections.     

Comparing Acute Effects of a Nano-TiO2 Pigment on Cosmopolitan Freshwater Phototrophic Microbes Using High-Throughput Screening

Production of titanium-dioxide nanomaterials (nano-TiO₂) is increasing, leading to potential risks associated with unintended release of these materials into aquatic ecosystems. We investigated the acute effects of nano-TiO₂ on metabolic activity and viability of algae and cyanobacteria using high-throughput screening. The responses of three diatoms (Surirella angusta, Cocconeis placentula, Achnanthidium lanceolatum), one green alga (Scenedesmus quadricauda), and three cyanobacteria (Microcystis aeruginosa, Gloeocapsa sp., Synechococcus cedrorum) to short-term exposure (15 to 60 min) to a common nano-TiO₂ pigment (PW6; average crystallite size 81.5 nm) with simulated solar illumination were assessed. Five concentrations of nano-TiO₂ (0.5, 2.5, 5, 10, and 25 mg L^-1) were tested and a fluorescent reporter (fluorescein diacetate) was used to assess metabolic activity. Algae were sensitive to nano-TiO₂, with all showing decreased metabolic activity after 30-min exposure to the lowest tested concentration. Microscopic observation of algae revealed increased abundance of dead cells with nano-TiO₂ exposure. Cyanobacteria were less sensitive to nano-TiO₂ than algae, with Gloeocapsa showing no significant decrease in activity with nano-TiO₂ exposure and Synechococcus showing an increase in activity. These results suggest that nanomaterial contamination has the potential to alter the distribution of phototrophic microbial taxa within freshwater ecosystems. The higher resistance of cyanobacteria could have significant implications as cyanobacteria represent a less nutritious food source for higher trophic levels and some cyanobacteria can produce toxins and contribute to harmful algal blooms.     

Antiviral efficacy of Limonium densiflorum against HSV-1 and influenza viruses

Viral infections remain a major threat to humans and animals and there is a crucial need for new antiviral agents especially with the development of resistant viruses. Several Limonium genus members (Plumbaginacea) have been widely used in traditional medicine for the treatment of infections. In this study, we investigated the antiviral activities of different fractions after successive extraction (hexane, dichloromethane, ethanol and methanol) of the halophyte Limonium densiflorum against H1N1 influenza and HSV-1 herpes viruses. In addition, TLC phytochemicals of the shoot extracts were analyzed. All extracts were tested for their cytotoxicity using a fluorometric resazurin assay. The antiviral activity of extracts was tested using four modes of action: virucidal test, pretreatment of cells with samples before infection, attachment assay and plaque reduction test. A good antiviral activity was found with ethanol and methanol extracts. They were most potent in HSV-1 inhibition than H1N1 influenza virus. The most potent inhibition was observed with ethanol extract, and it exhibited high levels of virucidal activity against HSV-1 (IC₅₀ = 6 μg/mL). It inhibits the replication of the virus by 75% when added after penetration of the virus, and by 100% when added during the viral attachment. It protects MDCK cells against influenza virus by abolishing virus to entry into the host cell (IC₅₀ = 55 μg/mL). After attachment of influenza virus, the ethanol extract displayed an appreciable inhibition of virus replication (IC₅₀ = 193 μg/mL). Methanol extract showed a moderate antiviral capacity against both viruses. While dichloromethane has excellent antiherpes potential, results were inappropriate because it was toxic to Vero cells, hexane extract has no effect. TLC analysis of these extracts showed that flavonoids and saponins were the major classes of natural products found in the shoot extracts that may be responsible for these antiviral activities.     

ANTIVIRAL ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified the order Chroococcales as commonly producing antiviral agents.     

SAR analysis of a series of acylthiourea derivatives possessing broad-spectrum antiviral activity

A series of acylthiourea derivatives were designed, synthesized, and evaluated for broad-spectrum antiviral activity with selected viruses from Poxviridae (vaccinia virus) and two different genera of the family Bunyaviridae (Rift Valley fever and La Crosse viruses). A compound selected from a library screen, compound 1, displayed submicromolar antiviral activity against both vaccinia virus (EC(50)=0.25 μM) and La Crosse virus (EC(50)=0.27 μM) in cytopathic effect (CPE) assays. SAR analysis was performed to further improve antiviral potency and to optimize drug-like properties of the initial hits. During our analysis, we identified 26, which was found to be nearly fourfold more potent than 1 against both vaccinia and La Crosse viruses. Selected compounds were further tested to more fully characterize the spectrum of antiviral activity. Many of these possessed single digit micromolar and sub-micromolar antiviral activity against a diverse array of targets, including influenza virus (Orthomyxoviridae), Tacaribe virus (Arenaviridae), and dengue virus (Flaviviridae).     

Comparative characteristics of physico-chemical and regulating properties of aspartate kinases from three species of cyanobacteria

Aspartokinases have been isolated from the cell-free extracts of Plectonema boryanum, Anabaena variabilis and Synechococcus cedrorum. Their physico-chemical characteristics and peculiarities of retroregulation by amino acids were studied. It has been shown that in P. boryanum cells aspartokinase reaction is catalyzed by only one enzyme, which is similar to the previously described bacterial origin enzymes. Three izoenzymes, which differ in their main properties and amino acids-effectors, have been founded in the cells of A. variabilis. One enzyme with aspartokinase activity, which differs from other cyanobacteria enzymes in some physico-chemical features has been founded in the cells of S. cedrorum.     

Viperin抑制黄病毒属感染作用机制研究进展

Viperin是近年来发现的具有重要免疫活性的宿主蛋白之一,其在细胞内的表达在病毒感染或干扰素诱导后明显上升,显示出广泛的抗病毒活性。已证实它可以影响许多囊膜病毒在宿主细胞中的组装和释放,但在不同的病毒中所表现的具体抗病毒活性不同。黄病毒属病毒为单股正链具囊膜的RNA病毒,该种属病毒具有相似的结构特征。Viperin蛋白可以抑制多数黄病毒在细胞中的复制。就Viperin抗几种黄病毒属病毒作用机制进行综述,为相关研究提供参考。     

Anti-herpetic activity of a sulfated xylomannan from Scinaia hatei

Many viruses display affinity for cell surface heparan sulfate proteoglycans with biological relevance in virus entry. This raises the possibility of the application of sulfated polysaccharides in antiviral therapy. In this study we have analyzed polysaccharide fractions isolated from Scinaia hatei. The crude water extract (ShWE) as well as one fraction (F1) obtained by size exclusion chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC50) values ranging from 0.5 to 4.6 microg/ml were much lower than the cytotoxic concentration 50% (CC50) values (1000 microg/ml). These fractions had very low anticoagulant activity. Furthermore, they had a weak inactivating effect on virions in a virucidal assay at concentrations in the range of 60-100 microg/ml. Chemical, chromatographic and spectroscopic methods showed that the major polysaccharide, which had 0.4 sulfate group per monomer unit and an apparent molecular mass of 160 kDa, contained a backbone of alpha-(1-->3)-linked D-mannopyranosyl residues substituted at C-6, C-4 and C-2 with single stub of beta-d-xylopyranosyl residues. Sulfate groups, when present, are located at C-4 of alpha-(1-->3)-linked D-mannopyranosyl units, and appeared to be very important for the anti-herpetic activity of this polymer.     

Antiviral activity of south Brazilian medicinal plant extracts.

Brazilian plants are potential sources of useful edible and medicinal plants. Hydromethanolic extracts prepared from 54 medicinal plants used in folk medicine to treat infections were screened for antiviral properties against five different viruses (HSV-1, HSV-2, poliovirus type 2, adenovirus type 2 and VSV). Fifty-two percent of the plant extracts exhibited antiviral against one or more tested viruses. More specifically, 42.6% showed activity against HSV-1 (herpes simplex virus type 1), 42.6% against HSV-2 (herpes simplex virus type 2), 26% against poliovirus and 24% against VSV (vesicular stomatitis virus). None of the extracts was active against adenovirus. Trixis praestans (Vell.) Cabr. and Cunila spicata Benth. extracts were further characterized for antiviral activity.     

ANTIVIRAL SUBSTANCES FROM CALIFORNIA MARINE ALGAE1

Extracts of 28 species of marine macroscopic algae collected from various coastal habitats of northern California were examined for antiviral activity against a broad spectrum of mammalian viruses. Ten members of Rhodophyta contained substance(s) which caused greater than a 2 log reduction in the infectivity of herpes simplex virus types 1 and 2. In addition, anti-Coxsackie B_s virus activity was detected in extracts of Constantinea simplex Setchell. The physical and chemical properties of the substance in extracts of Farlowia mollis (Harvey and Bailey) Farlow and Setchell and C. simplex indicated the active agent was a structural polysaccharide.