Antiviral activity of an extract from leaves of the tropical plant Acanthospermum hispidum

Antiviral activity of two Acanthospermum species against herpes simplex virus 1

ETHNOPHARMACOLOGICAL RELEVANCE

Acanthospermum species are used in traditional medicine for treating various pathologies, including bacterial and viral infections. In a screening study, we identified the activity of the ethanolic extracts of Acanthospermum australe and Acanthospermum hispidum against herpes simplex virus 1 (HSV-1).

AIM OF THE STUDY

In this work, we analyzed the phytochemical profile and antiviral activity of the chemical fractionation products of Acanthospermum australe and Acanthospermum hispidum. Additionally, we identified the effect of these fractions on different steps of the viral cycle.

MATERIALS AND METHODS

Acanthospermum samples were extracted with methanol and further partitioned with solvents of increasing polarities: hexane, chloroform, ethyl acetate, and butanol. Cytotoxicity and antiviral activity were analyzed for each fraction. The active fractions were tested to identify the virucidal effect and the inhibition of virus-cell binding. Further, the effect of these fractions on the replication and viral gene was quantitated by qPCR, and the expression of gD protein was evaluated by Western blot.

RESULTS

The chloroform and hexane fractions of Acanthospermum hispidum and Acanthospermum australe showed dose-dependent antiviral activity. The chloroform fraction inhibited the virus-cell binding and virus cycle in a post-entry mechanism by decreasing replication and the expression of early and late viral genes. The hexane fraction did not inhibit virus binding; however, it showed antiviral activity in post-entry events by inhibiting the immediate-early, early, and late genes. We identified in both species the presence of 3.6-dimetoxiapigenin, axillarin, and penduletin in the chloroform fraction and methyl-(Z,Z)-9,12-octadecadienoate and phytol in the hexane fraction.

CONCLUSIONS

Acanthospermum hispidum and Acanthospermum australe possess antiviral activity against HSV-1 and affect different steps of the viral cycle. These characteristics make them good candidates for developing phytotherapeutic products against HSV-1.

Ethnopharmacological investigations of the cardio-renal properties of a native species from the region of Pantanal, state of Mato Grosso do Sul, Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

Acanthospermum hispidum DC. is an important medicinal herb that belongs to family Asteraceae, popularly used as a diuretic and hypotensive in the region of Pantanal, state of Mato Grosso do Sul, Brazil. Despite the relevance of this species throughout the country, there are no detailed studies about its possible ethnobotanical indication.

AIM

To carry out a detailed ethnopharmacological investigation of the cardio-renal properties of A. hispidum.

MATERIALS AND METHODS

First, a detailed morpho-anatomical study with the purpose of characterizing and providing quality control parameters for the species was carried out. Then, purified aqueous extract (ESAH) was obtained and a detailed phytochemical investigation about its main secondary metabolites was performed. In addition, a thorough acute toxicological study was conducted to evaluate the actual toxic effects of this preparation. Finally, the possible diuretic and hypotensive effects of ESAH on male Wistar rats (30, 100, 300mg/kg; intraduodenally) were evaluated, and using pharmacological antagonists or inhibitors, the involvement of prostaglandin/cAMP and nitric oxide/cGMP pathway and potassium channels in ESAH-induced hypotension was investigated.

RESULTS

The analyses performed by liquid chromatography-mass spectrometry showed that the main secondary metabolites present in ESAH were phenolic compounds, such as caffeoylquinic acids (chlorogenic acid), dicaffeoylquinic acids and glycosylated flavonoids (quercetin glucoside and galactoside). ESAH did not induce any acute toxic effects and did not affect the urinary volume or renal excretion of electrolytes in Wistar rats. On the other hand, intraduodenal administration of ESAH induces a significant acute hypotensive effect. Previous treatment with N(G)-nitro-L-arginine methyl ester, methylene blue, or tetraethylammonium fully avoided the hypotensive effect of ESAH. All other parameters were not affected by treatment with ESAH.

CONCLUSION

Data obtained in this study allow us to suggest that ESAH obtained from A. hispidum presents an important acute hypotensive effect, which appears to be dependent on the nitric oxide/cGMP pathway. This study presents new evidences about the therapeutic potential of this species when acute hypotensive response is required.

Antiviral activity of an aqueous extract derived from Aloe arborescens Mill. against a broad panel of viruses causing infections of the upper respiratory tract

BACKGROUND

A number of antiviral therapies have evolved that may be effectively administered to treat respiratory viral diseases. But these therapies are very often of limited efficacy or have severe side effects. Therefore there is great interest in developing new efficacious and safe antiviral compounds e.g. based on the identification of compounds of herbal origin.

HYPOTHESIS

Since an aqueous extract of Aloe arborescens Mill. shows antiviral activity against viruses causing infections of the upper respiratory tract in vitro we hypothesised that a product containing it such as Biaron C(®) could have an antiviral activity too.

STUDY DESIGN

Antiviral activity of Bioaron C(®), an herbal medicinal product consisting of an aqueous extract of Aloe arborescens Mill., Vitamin C, and Aronia melanocarpa Elliot. succus, added as an excipient, was tested in vitro against a broad panel of viruses involved in upper respiratory tract infections.

METHODS

These studies included human adenovirus and several RNA viruses and were performed either with plaque reduction assays or with tests for the detection of a virus-caused cytopathic effect.

RESULTS

Our studies demonstrated an impressive activity of Bioaron C(®) against members of the orthomyxoviridae - influenza A and influenza B viruses. Replication of both analysed influenza A virus strains - H1N1 and H3N2 - as well as replication of two analysed influenza B viruses - strains Yamagatal and Beiying - was significantly reduced after addition of Bioaron C(®) to the infected cell cultures. In contrast antiviral activity of Bioaron C(®) against other RNA viruses showed a heterogeneous pattern. Bioaron C(®) inhibited the replication of human rhinovirus and coxsackievirus, both viruses belonging to the family of picornaviridae and both representing non-enveloped RNA viruses. In vitro infections with respiratory syncytial virus and parainfluenza virus, both belonging to the paramyxoviridae, were only poorly blocked by the test substance. No antiviral activity of Bioaron C(®) was detected against adenovirus - a non-enveloped DNA virus.

CONCLUSIONS

These results represent the first proof of a selective antiviral activity of Bioaron C(®) against influenza viruses and create basis for further analyses of type and molecular mechanisms of the antiviral activity of this herbal medicine.

Screening, isolation and optimization of anti-white spot syndrome virus drug derived from marine plants

OBJECTIVE

To screen, isolate and optimize anti-white spot syndrome virus (WSSV) drug derived from various marine floral ecosystems and to evaluate the efficacy of the same in host-pathogen interaction model.

METHODS

Thirty species of marine plants were subjected to Soxhlet extraction using water, ethanol, methanol and hexane as solvents. The 120 plant isolates thus obtained were screened for their in vivo anti-WSSV property in Litopenaeus vannamei. By means of chemical processes, the purified anti-WSSV plant isolate, MP07X was derived. The drug was optimized at various concentrations. Viral and immune genes were analysed using reverse transcriptase PCR to confirm the potency of the drug.

RESULTS

Nine plant isolates exhibited significant survivability in host. The drug MP07X thus formulated showing 85% survivability in host. The surviving shrimps were nested PCR negative at the end of the 15 d experimentation. The lowest concentration of MP07X required intramuscularly for virucidal property was 10 mg/mL. The oral dosage of 1 000 mg/kg body weight/day survived at the rate of 85%. Neither VP28 nor ie 1 was expressed in the test samples at 42nd hour and 84th hour post viral infection.

CONCLUSIONS

The drug MP07X derived from Rhizophora mucronata is a potent anti-WSSV drug.

Screening, isolation and optimization of anti-white spot syndrome virus drug derived from terrestrial plants

OBJECTIVE

To screen, isolate and optimize anti-white spot syndrome virus (WSSV) drug derived from various terrestrial plants and to evaluate the efficacy of the same in host-pathogen interaction model.

METHODS

Thirty plants were subjected to Soxhlet extraction using water, ethanol, methanol and hexane as solvents. The 120 plant isolates thus obtained were screened for their in vivo anti-WSSV property in Litopenaeus vannamei. The best anti-WSSV plant isolate, TP22C was isolated and further analyzed. The drug was optimized at various concentrations. Viral and immune genes were analysed using reverse transcriptase PCR to confirm the potency of the drug.

RESULTS

Seven plant isolates exhibited significant survivability in host. The drug TP22C thus formulated showed 86% survivability in host. The surviving shrimps were nested PCR negative at the end of the 15 d experimentation. The lowest concentration of TP22C required intramuscularly for virucidal property was 10 mg/mL. The oral dosage of 750 mg/kg body weight/day survived at the rate of 86%. Neither VP28 nor ie 1 was expressed in the test samples at 42nd hour and 84th hour post viral infection.

CONCLUSIONS

The drug TP22C derived from Momordica charantia is a potent anti-white spot syndrome virus drug.

Bioactivity of the Essential Oil of an Argentine Collection of Acanthospermum hispidum (Asteraceae)

The essential oil of an Argentine collection of the annual herb Acanthospermum hispidum DC. (Asteraceae), which contains the sesquiterpenoids β-caryophyllene (35.2%), α-bisabolol (11.4%), and germacrene D (11.1%) as major constituents, displayed molluscicidal effects on an adult population of Biomphalaria peregrina Orbigny (LD50 37.8 μg/mL) and produced alteration of the feeding and oviposition behavior of the polyphagous insect Spodoptera frugiperda Smith when incorporated in the larval diet at 250 μg/g. In addition, a selective antibacterial activity was observed against pathogenic strains of Staphylococcus aureus and Enterococcus faecalis (MICs 62.5 and 125 μg/mL), but was inactive at 125 μg/mL against three beneficial lactic acid bacteria. Synergistic interactions were further validated by FIC index determination of the combination of the antibiotics oxacillin and gentamicin and the essential oil on the four pathogenic strains evaluated.

Antiviral activity in vitro of two preparations of the herbal medicinal product Sinupret® against viruses causing respiratory infections

Sinupret(®), a herbal medicinal product made from Gentian root, Primula flower, Elder flower, Sorrel herb, and Verbena herb is frequently used in the treatment of acute and chronic rhinosinusitis and respiratory viral infections such as common cold. To date little is known about its potential antiviral activity. Therefore experiments have been performed to measure the antiviral activity of Sinupret(®) oral drops (hereinafter referred to as "oral drops") and Sinupret(®) dry extract (hereinafter referred to as "dry extract"), in vitro against a broad panel of both enveloped and non-enveloped human pathogenic RNA and DNA viruses known to cause infections of the upper respiratory tract: influenza A, Chile 1/83 (H1N1) virus (FluA), Porcine Influenza A/California/07/2009 (H1N1) virus (pFluA), parainfluenza type 3 virus (Para 3), respiratory syncytial virus, strain Long (RSV), human rhinovirus B subtype 14 (HRV 14), coxsackievirus subtype A9 (CA9), and adenovirus C subtype 5 (Adeno 5). Concentration-dependent antiviral activity (EC(50) between 13.8 and 124.8 μg/ml) of Sinupret(®) was observed against RNA as well as DNA viruses independent of a viral envelope. Remarkable antiviral activity was shown against Adeno 5, HRV 14 and RSV in which dry extract was significantly superior to oral drops. This could be ascertained with different assays as plaque-reduction assays in plaque forming units (PFU), the analyses of a cytopathogenic effect (CPE) and with enzyme immunoassays (ELISA) to determine the amount of newly synthesised virus. Our results demonstrate that Sinupret(®) shows a broad spectrum of antiviral activity in vitro against viruses commonly known to cause respiratory infections.

In vitro antiviral activity from Acanthospermum australe on herpesvirus and poliovirus

CONTEXT

The Asteraceae family has been of interest to researchers due to the presence of polyphenolic compounds, mainly flavonoids, which demonstrated antiviral activity.

OBJECTIVE

The hydroethanol extract of the aerial parts of Acanthospermum australe (Loefl.) Kuntze (Asteraceae) and its fractions, were evaluated in vitro for their potential cytotoxic and antiviral activity against bovine herpesvirus and human poliovirus.

MATERIALS AND METHODS

The sulforhodamine B colorimetric assay were used to evaluate the capacity of the hydroethanol extract and fractions to inhibit the lytic activity of herpes and poliovirus in infected cell cultures and their influence on the viability of uninfected cell cultures.

RESULTS AND DISCUSSION

A progressive increase in the antiviral effect against herpesvirus was observed in the course of the purification process of the extract. The hydroethanol extract had a 50% antiviral effective concentration (EC(50)) at 70 μg/mL and 36 μg/mL for herpes and poliovirus, respectively, and it exhibited no cytotoxicity. The fractions F3 (dichloromethane) and F4 (dichloromethane: ethyl acetate (1:1 v/v)) both showed EC(50) at 6.25 μg/mL against herpesvirus, and these fractions showed cytotoxic concentrations (CC(50)) at 12.7 and 11.7 μg/mL, respectively. These fractions had no effect against poliovirus in the concentrations tested. From the bioactive F3, a diterpene lactone (acanthoaustralide-1-O-acetate) was isolated at a concentration of 0.5% and from F4 two flavonoids (quercetin and chrysosplenol D) were isolated at concentrations of 0.14 and 0.24%, respectively.

CONCLUSION

The present study reports for the first time the antiviral activity of extracts and fractions from A. australe aerial parts.

Comparative Analysis of the Essential Oils from two Asteraceous Plants Found in Nigeria, Acanthospermum Hispidum and Tithonia Diversifolia

The essential oils from two members of the Asteraceae ( Acanthospermum hispidum DC. aerial parts, and leaves of Tithonia diversifolia (Hemsley) A. Gray), growing wild in Osun State, Nigeria, have been characterised by combined gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses. Twenty-nine components have been fully identified and grouped into monoterpene hydrocarbons (22.2%), oxygenated monoterpenes (4.6%), sesquiterpenes hydrocarbons (58.2%) and oxygenated sesquiterpenes (10.8%) in A. hispidum. The main constituents of the oil were β-caryophyllene (28.0%), α-pinene (15.9%) and bicyclogermacrene (11.0%) among the hydrocarbon compounds, and bisabolol (8.9%) and carvacrol methyl ether (4.1%) among the oxygenated components. Tithonia diversifolia essential oil comprised seventeen components and was characterised by a predominant content of monoterpene hydrocarbons (87.9%), cis-β-ocimene (43.7%), α-pinene (28.6%) and limonene (12.0%) being the main compounds. Sesquiterpenes represented ca. 10% oil, as sum of hydrocarbons and oxygenated components. A new chemotype is established for T. diversifolia, while the Nigerian A. hispidum is being reported for the first time as a new source of essential oil with some distinction in composition from those of other sources.

In vitro evaluation of the antiviral effects of the homeopathic preparation Gripp-Heel on selected respiratory viruses

Gripp-Heel is a homeopathic preparation frequently used in the treatment of respiratory viral infections such as various types of influenza and the common cold. The antiviral activity of Gripp-Heel was studied in vitro on human pathogenic enveloped and nonenveloped RNA and DNA viruses. Before the antiviral assays, in vitro cytotoxicity of Gripp-Heel was determined with cells used for the infection experiments (HeLa, HEp-2, MDCK, BGM) as well as with mitogen-stimulated peripheral blood mononuclear leukocytes. A concentration of 0.5 of the commercially available product slightly reduced cell viability and proliferative capacity, and experiments on antiviral activity were determined starting with a dilution of 0.2 of the commercially available product. The antiviral activity was determined against a broad panel of enveloped and nonenveloped DNA and RNA viruses with plaque reduction assay, cytopathogenic assays, virus titrations, analysis of the viral proteins in virus-specific enzyme immunoassays, and haemagglutination tests. Control substances were acyclovir (10 microg/mL), ribavirin (6 microg/mL), and amantadine hydrochloride (5 microg/mL), depending on the virus type. Gripp-Heel demonstrated dose-dependent in vitro activity (significant reductions of infectivity by 20% to 40%) against Human herpesvirus 1, Human adenovirus C serotype 5, Influenza A virus, Human respiratory syncytial virus, Human parainfluenza virus 3, Human rhinovirus B serotype 14, and Human coxsackievirus serotype A9. The mechanisms of this antiviral activity are still unclear, but type I interferon induction might be a possible explanation. Further research on this homeopathic preparation seems warranted.

Inhibitory effect of essential oils against herpes simplex virus type 2

Essential oils from anise, hyssop, thyme, ginger, camomile and sandalwood were screened for their inhibitory effect against herpes simplex virus type 2 (HSV-2) in vitro on RC-37 cells using a plaque reduction assay. Genital herpes is a chronic, persistent infection spreading efficiently and silently as sexually transmitted disease through the population. Antiviral agents currently applied for the treatment of herpesvirus infections include acyclovir and its derivatives. The inhibitory concentrations (IC50) were determined at 0.016%, 0.0075%, 0.007%, 0.004%, 0.003% and 0.0015% for anise oil, hyssop oil, thyme oil, ginger oil, camomile oil and sandalwood oil, respectively. A clearly dose-dependent virucidal activity against HSV-2 could be demonstrated for all essential oils tested. In order to determine the mode of the inhibitory effect, essential oils were added at different stages during the viral infection cycle. At maximum noncytotoxic concentrations of the essential oils, plaque formation was significantly reduced by more than 90% when HSV-2 was preincubated with hyssop oil, thyme oil or ginger oil. However, no inhibitory effect could be observed when the essential oils were added to the cells prior to infection with HSV-2 or after the adsorption period. These results indicate that essential oils affected HSV-2 mainly before adsorption probably by interacting with the viral envelope. Camomile oil exhibited a high selectivity index and seems to be a promising candidate for topical therapeutic application as virucidal agents for treatment of herpes genitalis.

Porcine γδ T cells: Possible roles on the innate and adaptive immune responses following virus infection

gammadelta T cells recognise different types of antigen in alternative ways to alphabeta T cells, and thus appear to play a complementary role in the immune response. However, unlike alphabeta T cells, the role or function of gammadelta T cells is still unclear. As pigs possess a high proportion of circulating gammadelta T cells, they are suitable large animal model to study gammadelta T cell functions. This as yet has not been fully exploited, leaving porcine gammadelta T cell biology and its role in immunity in its infancy. Foot-and-mouth disease (FMD) high potency "emergency" vaccines are able to induce early protection from challenge and it has been suggested that, in part, there is some involvement of innate immune responses. The antigen component of the vaccine is able to stimulate purified naive pig gammadelta T cells and induce the mRNA of various cytokines and chemokines. This observation suggests that gammadelta T cells probably contribute to the early phase of the immune responses to FMD vaccination, and perhaps infection. A subset of these circulating gammadelta T cells display a phenotype similar to professional antigen presenting cells and are able to take up and present soluble antigen to CD4(+) T cells in a direct cell-cell interaction via MHC class II. This direct interaction between gammadelta T cells and CD4(+) T cells is likely to have a significant influence on the out come of the adaptive immune response.

Natural Products as Antiviral Agents

Since the ancient times, natural products have served as a major source of drugs. About fifty percent of today's pharmaceutical drugs are derived from natural origin. Interest in natural products as a source of new drugs is growing due to many factors that will be discussed in this article. Viruses have been resistant to therapy or prophylaxis longer than any other form of life. Currently, there are only few drugs available for the cure of viral diseases including acyclovir which is modeled on a natural product parent. In order to combat viruses which have devastating effects on humans, animals, insects, crop plants, fungi and bacteria, many research efforts have been devoted for the discovery of new antiviral natural products. Recent analysis of the number and sources of antiviral agents reported mainly in the annual reports of medicinal chemistry from 1984 to 1995 indicated that seven out of ten synthetic agents approved by FDA between 1983-1994, are modeled on a natural product parent. It has been estimated that only 5-15% of the approximately 250,000 species of higher plants have been systematically investigated for the presence of bioactive compounds while the potential of the marine environment has barely been tapped. The aim of this review is to provide an overview on the central role of natural products in the discovery and development of new antiviral drugs by displaying 340 structures of plant, marine and microbial origin that show promising in vitro antiviral activity.