The antiviral potency of Fagus sylvatica 4OMe-glucuronoxylan sulfates.

Herpes simplex virus belongs to Herpesviridae family and causes infection of humans from ancient times. 4OMe-glucuronoxylans as the renewable biopolymers can be promising glycomaterials for various applications in pharmacy. Control enzymatic degradation of the native 4OMe-glucuronoxylan (GX1) followed by targeted sulfation procedure afforded a range of 4OMe-glucuronoxylan sulfates differed in the degree of sulfation (10-16%) and molecular mass (21,000-5000g/mol; GXS1>GXS2>GXS3>GXS4). Antiviral activity tests on GXS1-4 against herpes simplex virus (HSV) types 1 and 2 revealed the positive effect of all compounds against strains of herpes virus. Of them, the compounds GXS1 and GXS4 were shown to be the most active for both HSV serotypes. The antiviral activity of GXS1 and GXS4 was similar to those of heparin or dextran sulfate, used as reference compounds. It was found that GXS1 and GXS4 were active as well against Polio and dengue viruses, however, on a smaller scale. The mode of antiviral action of 4OMe-glucuronoxylan sulfates is due to inhibition of the virus binding to the cell receptors.

The antiviral activity of sulfated polysaccharides against dengue virus is dependent on virus serotype and host cell.

Two homogeneous sulfated polysaccharides obtained from the red seaweeds Gymnogongrus griffithsiae and Cryptonemia crenulata, the kappa/iota/nu carrageenan G3d and the dl-galactan hybrid C2S-3, were assayed for their antiviral properties against the four serotypes of dengue virus (DENV) in different host cell types. Both seaweed derivatives were selective inhibitors of DENV-2 multiplication in Vero cells with inhibitory concentration 50% (IC50) values around 1 microg/ml and selectivity indices > 1000. The compounds had a lower antiviral effect against DENV-3 (IC50 values in the range 13.9-14.2 microg/ml), an even lower effect against DENV-4 (IC50 values in the range 29.3 to > 50 microg/ml) and were totally inactive against DENV-1. With respect to the host cell, the polysulfates were inhibitors of DENV-2 and DENV-3 in the human hepatoma HepG2 and foreskin PH cells, with similar antiviral effectiveness as in Vero cells, but were totally inactive in mosquito C6/36 HT cells. Mechanistic studies demonstrated that G3d and C2S-3 were active DENV-2 inhibitors only when added together with the virus or early after infection, and both initial processes of virus adsorption and internalization are the main targets of these compounds. Therefore, the variations in antiviral activity of the polysaccharides depending on the viral serotype and the host cell may be ascribed to differences in the virus-cell interaction leading to virus entry.

Antiviral activity of a sulphated polysaccharide from the red seaweed Nothogenia fastigiata.

The antiviral activity of polysaccharide fractions obtained from water extracts of the red seaweed Nothogenia fastigiata was investigated. Fraction F6, corresponding to a sulphated xylomannan, was found to inhibit efficiently the replication of herpes simplex virus type 1 (HSV-1). Furthermore, F6 selectively inhibited the replication of several other enveloped viruses including herpes simplex virus type 2, human cytomegalovirus (HCMV), respiratory syncytial virus, influenza A and B virus, Junin and Tacaribe virus and simian immunodeficiency virus. F6 was only weakly active against human immunodeficiency virus type 1 and 2. The mode of action of F6 against HSV-1 and HCMV could be ascribed to an inhibitory effect on virus adsorption.

Coupling of foot-and-mouth disease virus to sheep red blood cells using tannic acid for immunological assays.

A technique for coupling foot-and-mouth disease virus (FMDV) to tanned sheep red blood cells (SRBC) is reported. Different parameters influencing the procedure were studied. Subtypes C2, C3, O1 and A24 were used as antigens, and guinea pig hyperimmune sera obtained were tested for specific antibody in passive hemagglutination (PH), passive hemagglutination inhibition (PHI) and passive immune hemolysis (PIL) assays. Fresh and SRBC stored in Alsever's solution showed similar behavior when used as indicator cells. Optimal sensitization of erythrocytes was achieved using tannic acid 1:20,000 and 20 micrograms of purified virus/ml at pH 7.6. Specificity of the reaction was confirmed by PH and PHI in homologous and heterologous systems. The coupled antigen-antibody complex was sensitive to complement mediated lysis in a PIL test.

Novel DL-galactan hybrids from the red seaweed Gymnogongrus torulosus are potent inhibitors of herpes simplex virus and dengue virus.

A novel series of DL-galactan hybrids extracted from the red seaweed Gymnogongrus torulosus, was evaluated for its in vitro antiviral properties against herpes simplex virus type 2 (HSV-2) and dengue virus 2 (DEN-2). These compounds were very active against both viruses with inhibitory concentration 50% (IC50) values in the range 0.6-16 microg/ml for HSV-2 and 0.19-1.7 microg/ml for DEN-2, respectively, as determined in a virus plaque reduction assay in Vero cells. The DL-galactans lacked of cytotoxic effects, on stationary as well as on actively dividing cells, and anticoagulant properties. Some of the compounds showed a variable level of direct inactivating effect on both virions, with virucidal concentration 50% values exceeding the IC50s obtained by plaque reduction assay. Full inhibitory activity was achieved when the galactans were present during virus adsorption period, suggesting that the mode of action of these compounds is an interference in the binding of the surface envelope glycoprotein with the cell receptor.

Evaluation of the antiviral activity of natural sulfated polyhydroxysteroids and their synthetic derivatives and analogs.

Disodium 3beta,21-dihydroxypregn-5-en-20-one disulfate (2), sodium 3beta,21-dihydroxypregn-5-en-20-one 3-sulfate (3), sodium 3beta,21-dihydroxypregn-5-en-20-one 21-sulfate (4), and disodium 3beta,6alpha-dihydroxy-5alpha-pregnan-20-one disulfate (6) have been synthesized and completely characterized for the first time from readily available materials. Sulfation was performed using triethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. Selective sulfation of 3beta,21-dihydroxypregn-5-en-20-one rendered sodium 3beta,21-dihydroxypregn-5-en-20-one 3-sulfate (3) as the major compound. The synthetic sulfated steroids as well as natural disulfated polyhydroxysteroids (7-9) isolated by us from the antarctic ophiuroid Astrotoma agassizii and the synthetic derivatives disodium 2beta,3alpha,21-trihydroxy-(20R)-cholesta-5,24-diene 3-acetate, 2,21-disulfate (7a) and 2beta,3alpha,21-trihydroxy-(20R)-cholesta-5,24-diene (7b) were comparatively evaluated for their inhibitory effect on the replication of one DNA (HSV-2) and two RNA (PV-3, JV) viruses. In general, steroids with sulfate groups at C-21 and C-2 or C-3 were the most effective in their inhibitory action against HSV-2 and also proved to be active against PV-3 and JV.

The system of sulfated alpha-(1-->3)-linked D-mannans from the red seaweed Nothogenia fastigiata: structures, antiherpetic and anticoagulant properties.

Structural analysis of two xylomannans extracted from Nothogenia fastigiata was carried out. The results are consistent with the general pattern previously reported for other xylo-mannans of the same system, alpha-(1-->3)-linked D-mannans 2- and 6-sulfated and having single stubs of beta-(1-->2)-linked D-xylose, but one of the new samples contains a significant amount of 2,6-disulfated units. Both xylomannans studied are obtained as complexes with a beta-D-(1-->3)-, alpha-L-(1-->4)-galactan and a beta-D-(1-->3)-, beta-D-(1-->4)-'mixed linkage' xylan co-existing in the seaweed, a fact that limits the accuracy of the data determined. The structures of the galactan and the xylan are similar to those previously informed for this seaweed. The antiviral activity against four different herpes simplex viral strains and the anticoagulant properties of all the xylo-mannans of the system are reported.

Antiherpetic and anticoagulant properties of carrageenans from the red seaweed Gigartina skottsbergii and their cyclized derivatives: correlation between structure and biological activity.

The antiviral activity against herpes simplex virus types 1 and 2 of kappa/l-, partially cyclized mu/v-, and lambda-carrageenans isolated from the red seaweed Gigartina skottsbergii and their cyclized derivatives was analyzed. lambda-Carrageenans and the partially cyclized mu/v-carrageenan were the most potent inhibitors of herpes viruses (including acyclovir-resistant variants and clinical isolates), with IC50 values lower than 1 microgram ml-1 against both serotypes and selectivity indices higher than 10(3). kappa/l-Carrageenans were slightly less effective than the other two types with IC50 values in the range 1.6-4.1 micrograms ml-1. Antiherpetic activity was directly correlated to the amount of alpha-D-galactose 2,6-disulfate residues in the natural carrageenans. The cyclization of the alpha-D-galactose 6-sulfate and 2,6-disulfate units into 3,6-anhydro-alpha-D-galactose and 3,6-anhydro-alpha-D-galactose 2-sulfate residues in these polysaccharides, in general, lowers the antiherpetic activity of the derivatives with respect to the natural carrageenans. Some carrageenans showed a very reduced anticoagulant activity only at concentrations that were considerably higher than the IC50, whereas others were totally devoid of anticoagulant properties. Among natural carrageenans, the mu/v-type IC3 shows the best relationship between antiviral efficacy and lack of anticoagulant action, resulting a very promising compound.

Trichuris chilensis: physicochemical and immunological characterization of the different antigenic components.

The protein pattern of Trichuris chilensis obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was analyzed. Complex protein band patterns covering a wide range of molecular weights were obtained. The molecular weights of the major proteins present in different tissue homogenates were estimated. Antisera raised in rabbits against homogenates of T. chilensis and sera from naturally infected Ctenomys australis were used in Western blotting, immunoelectrophoresis and passive hemagglutination to compare the antigenicity of the adult male, adult female, eggs, oocytes, stichosome and cuticle of this parasite. Specific antibodies to parasite antigens were also detected in faecal preparations and caecum mucosal extracts of C. australis naturally infected with T. chilensis.

[Determination of the antiviral activity of a naturally occurring sulfated xylomannan under various experimental conditions]. / Determinación de la actividad antiviral de un xilomanano sulfatado de origen natural en distintas condiciones experimentales.

The effects of different experimental conditions on the antiviral activity of the sulphated xylomannan F6, isolated from the red seaweed Nothogenia fastigiata, against the replication of herpes simplex virus type 1 and 2 (HSV-1 and HSV-2) were studied. The compound was equally effective against several strains of HSV-1 (F, KOS, B-2006 and Field) and HSV-2 (G) in different cell lines (Vero, HEp-2 and BHK-21). Furthermore, the antiviral activity of F6 was independent of the method employed to determine the 50% inhibitory concentration (IC50) (virus yield or plaque reduction tests). The value of the IC50 against HSV-1 was not significantly affected by the initial virus concentration since a variation in the multiplicity of infection from 0.0001 to 0.1 UFP/cell only increased twofold the IC50 from 0.61 to 1.35 micrograms/ml, respectively. The potent inhibitory effect of F6 against high doses of HSV-1 represents a significant advantage for this sulphated polysaccharide with respect to other compounds only active against low viral inocula.

[Comparison of various methods for the measurement of the humoral immune response in mice vaccinated with aphthous fever virus]. / Comparación de distintos métodos para la medición de la respuesta inmune humoral de ratones vacunados con el virus de la fiebre aftosa.

Kinetics of the humoral immune primary response and seven-day secondary response of adult CF1 mice to FMDV O1 Campos adjuvanted in aluminium hydroxide-saponin (AHS) or in oil emulsion (OE) were evaluated by means of ELISA and passive hemagglutination (PH). Analysis of the response to AHS vaccine showed that ELISA measured maximal titres of primary response at 23 days post-vaccination (dpv), and at day 17 of secondary response, while PH detected maximal titres for primary as well as secondary response around day 60 pv. Mice immunized with OE vaccine studied by ELISA presented a plateau of primary response around 40 dpv, while secondary response was maximal around 80 dpv. The same sera tested by PH showed the highest titres for primary response on day 50 pv and secondary response was maximal on day 40 pv. A criterion for the evaluation of vaccination efficiency in the murine model is proposed based on the methods employed in the determination of antibody level.

Antiviral activity of a carrageenan from Gigartina skottsbergii against intraperitoneal murine herpes simplex virus infection.

The partially cyclized mu/nu-carrageenan 1C3, isolated from the red seaweed Gigartina skottsbergii, was previously shown to be a potent inhibitor of the in vitro replication of Herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). Here the protective effect of 1C3 in a murine model of intraperitoneal ( i. p.) HSV-1 infection was evaluated. OF1 mice were i. p. infected with 5 x 10 (5) PFU of HSV-1 KOS strain, and the effects of different treatments with 1C3 were studied. When 30 mg/kg of body weight of 1C3 was administered by the i. p. route immediately after HSV-1 infection, 87.5 % survival of the animals was achieved (p < 0.005), associated with a delay in the mean day of death in 1C3-treated non-surviving mice. Animal survival was not improved when multiple doses of 1C3 were also given in the period 1 - 48 h post-infection, and no protection was afforded when treatment was started after 24 h of infection. When virus and compound were injected by different routes, i. p. and intravenous ( i. v.), respectively, a still significant protection was achieved (40 % survival, p < 0.05). No toxicity of 1C3 for the animals was recorded. The pharmacokinetic properties were analyzed after injection of 1C3 into the tail vein by monitoring of [ (3)H]-1C3 in plasma and organs and by a bioassay of the anti-HSV-1 activity remaining in serum after non-radioactive 1C3 inoculation. A very rapid disappearance of the compound from the blood was observed since only 5.9 - 0.9 % of the radioactivity of the initially administered [ (3)H]-1C3 appeared in the plasma between 5-300 minutes after administration. A transient peak of radioactivity was detected in the kidney 15 minutes after inoculation. The bioassay confirms the presence of the compound circulating in a biologically active form up to 1 hour after injection.

[Immunological studies in 2 species of Ceratophrys (Anura Leptodactylidae): C. ornata (Bell, 1843) and C. cranwelli (Barrio, 1979)]. / Estudios inmunológicos en dos especies afines de Ceratophrys (Anura Leptodactylidae): C. ornata (Bell, 1843) y C. cranwelli (Barrio, 1979).

Two related species of the genus Ceratophrys (C. ornata and C. cranwelli) were studied by immunological techniques in order to find non-morphological characters which would allow to classify them more precisely. Bidimensional immunodiffusion of serum proteins showed extensive crossreactivity between both species, thus revealing their close relatíonship. However, by immunoelectrophoretic techniques, differences between their serum fractions were detected. The antisera raised in rabbits against the serum proteins showed different potency in reacting with the sera of each species. Sharper precipitation bands were obtained with the homologous serum. Two lipoproteic fractions, in the serum of both species, were also characterized.

Inhibitory action of an algal derived xylomannan on glycoprotein C - mediated biological properties of Herpes simplex virus.

A purified sulfated xylomannan, named F6, obtained from the red seaweed Nothogenia fastigiata, proved to be a potent inhibitor of HSV-1 in vitro without affecting cell viability. In a virus yield reduction assay, the inhibitory concentration 50% (IC(50)) was 0.66 µg/ml. The mode of action of F6 was ascribed to an inhibitory effect on virus adsorption. The glycoprotein C (gC) of HSV-1 is involved in virus binding to the cell surface heparan sulfate. Furthermore, it mediates other biological activities such as induction of hemagglutination and binding to the third component of complement C(3)b. The compound F6 was effective in inhibiting hemagglutination induced by HSV-1 and also causes a reduction of 50% in rosette formation between sheep red blood cells coupled to C(3)b and cells infected with HSV-1, when added to the reaction mixture in a final concentration of 0.39 and 0.90 µg/ml, respectively. These experiments demonstrate that F6 not only inhibits the adsorption of HSV-l to susceptible cells but also interferes with other biological properties of the virus in which gC is involved, supporting the hypothesis of an interaction between F6 and the viral glycoprotein.

Synthesis of C-5'-nor-dideoxycarbanucleosides structurally related to neplanocin C.

Purine carbanucleosides built on a 6-oxabicyclo[3.1.0]hexane template were synthesized from readily available 2-cyclopentenone employing a Mitsunobu reaction to incorporate the base onto the carbocyclic ring. Both adenosine and guanosine analogues exhibited moderate antiviral activity.

Antiviral sulfated steroids from the ophiuroid Ophioplocus januarii.

One new and three known sulfated steroidal polyols have been isolated from the ophiuroid Ophioplocus januarii, collected at San Antonio Oeste, Río Negro, Argentina. The four compounds possess 4 alpha,11 beta-dihydroxy-3 alpha,21-disulfoxy substituents and the A/B cis ring junction but differ in the side chain. The new compound has been characterized as (22E)-5 beta-24-norcholest-22-ene-3 alpha,4 alpha,11 beta,21-tetrol 3,21-disulfate (4). The structures of the four compounds were determined from spectral data and comparison with those of related steroidal polyols. The four compounds were tested for their inhibitory effect on the replication of one DNA and three RNA viruses. Compounds 2 and 4 were active against respiratory syncytial and polio viruses, and compound 3 inhibited Junin virus, responsible for Argentine hemorrhagic fever.

Inhibitory effect of sulfated galactans from the marine alga Bostrychia montagnei on herpes simplex virus replication in vitro.

Sulfated polysaccharides exhibit many biological properties such as antiviral and anticoagulant activities. Herein, we report the antiviral activity of sulfated galactans extracted from the red sea-weed Bostrychia montagnei against herpes simplex virus types 1 (strain F and the thymidine kinase-deficient strains Field and B2006) and 2 (strain G). Two crude extracts obtained with cold and hot water as well as some fractions obtained by anion exchange chromatography, inhibited significantly the replication of the different strains of herpesviruses as determined by plaque reduction assays. The inhibitory effect of the compounds studied here took place only when they were added during the adsorption period. They were found to be highly selective antiviral substances, causing no impairment of Vero cell viability. Furthermore, they had no direct inactivating effect on virions by incubation in a virucidal assay. The antiviral activity could be correlated with the molecular weight and sulfate content of the polysaccharides. Although sulfated polysaccharides are generally endowed with anticoagulant properties, the results of the activated partial thromboplastin time and the thrombine time assays indicated that the natural sulfated polysaccharides from Bostrychia montagnei have very low anticoagulant activity, confirming that there is no relation between the antiviral and anticoagulant properties.

Two new cytotoxic and virucidal trisulfated triterpene glycosides from the Antarctic sea cucumber Staurocucumis liouvillei.

Two new trisulfated triterpene glycosides, liouvillosides A (1) and B (2), have been isolated from the Antarctic sea cucumber Staurocucumis liouvillei. Their structures have been elucidated by spectroscopic analysis (NMR and FABMS) and chemical transformations. Liouvillosides A (1) and B (2) are two new examples of a small number of trisulfated triterpene glycosides from sea cucumbers belonging to the family Cucumariidae. Both glycosides were found to be virucidal against herpes simplex virus type 1 (HSV-1) at concentrations below 10 microg/mL.

Determinación de la actividad antiviral de un xilomanano sulfatado de origen natural en distintas condiciones experimentales / Determination of the antiviral activity of a natural sulphated xylomannan under different experimental conditions

Se analizó la influencia de distintas condiciones experimentales sobre la determinación de la actividad antiviral del xilomanano sulfatado F6, aislado del alga roja patagónica Nothogenia fastigiata, sobre la multiplicación de los virus herpes simplex tipos 1 y 2 (HSV-1 y HSV-2). En las condiciones ensayadas, la concentración inhibitoria 50 por ciento (CI50) de F6 resultó independiente de la multiplicidad de infección (en el rango 0,1-0,0001 UFP/célula), del tipo de ensayo antiviral empleado (inhibición del rendimiento viral o reducción en la formación de placas), de la cepa de virus (F, KOS, B2006, Field) y de la línea celular (Vero, HEp-2, BHK-21). La independencia del efecto inhibitorio de F6 respecto de la multiplicidad de infección representa una ventaja para este polisacárido respecto de otros compuestos antivirales que sólo son activos frente a muy bajas dosis de virus

Comparación de distintos métodos para la medición de la respuesta inmune humoral de ratones vacunados con el virus de la fiebre aftosa / [Comparison of various methods for the measurement of the humoral immune response in mice vaccinated with aphthous fever virus]

Kinetics of the humoral immune primary response and seven-day secondary response of adult CF1 mice to FMDV O1 Campos adjuvanted in aluminium hydroxide-saponin (AHS) or in oil emulsion (OE) were evaluated by means of ELISA and passive hemagglutination (PH). Analysis of the response to AHS vaccine showed that ELISA measured maximal titres of primary response at 23 days post-vaccination (dpv), and at day 17 of secondary response, while PH detected maximal titres for primary as well as secondary response around day 60 pv. Mice immunized with OE vaccine studied by ELISA presented a plateau of primary response around 40 dpv, while secondary response was maximal around 80 dpv. The same sera tested by PH showed the highest titres for primary response on day 50 pv and secondary response was maximal on day 40 pv. A criterion for the evaluation of vaccination efficiency in the murine model is proposed based on the methods employed in the determination of antibody level.