Aims: Agaricus brasiliensis (previously named Agaricus blazei ss. Heinem), also known as the sun mushroom is native of Southeast Brazil, and is widely consumed, mainly in the form of tea, due to its nutritional and pharmacological properties. In this study, we tested aqueous (AqE) and ethanol (EtOHE) extracts and an isolated polysaccharide (PLS) from the fruiting body of A. brasiliensis, for antiviral activity against poliovirus type 1 in HEp‐2 cells. Methods and Results: The evaluation of the time of addition by plaque assay showed that when AqE, PLS and EtOHE were added, just after the virus inoculation (time 0 h), there was a concentration‐dependent reduction in the number of plaques up to 50%, 67% and 88%, respectively, with a selectivity index (SI) of 5·4, 9·9 and 12·3, respectively. Conclusions: The test substances showed antiviral activity and were more effective when added during the poliovirus infection. As they had little effect on reducing viral adsorption and did not show any virucidal effect, we suggest that they act at the initial stage of the replication of poliovirus. Significance and Impact of the Study: These results corroborate that basidiomycetes can be a rich source of potential antiviral compounds.
The aqueous extract of Agaricus blazei Murill ss. Heinem, a basidiomycete native from Brazil, frequently used by popular medicine, mainly in the form of tea, was assessed to its antiviral action against herpes simplex type 1 (HSV-1) and bovine herpes type 1 (BoHV-1) in HEp-2 cell culture. Viral replication inhibition was evaluated by plaque assay and immunofluorescence test. The extract demonstrated virucide action for both viruses, being more effective against HSV-1, inhibiting its infectivity in 78.4 and 73.9% at the concentrations of 50 and 100 µg/mL, respectively moreover, reduction in 47% the number of fluorescent cells was observed for both concentrations. The extract also showed discrete therapeutic activity. These results suggest that A. blazei extract acts mainly in the viral particle, however, the effect during virus replication can not be ruled out.
Aims: Chlorophyllin (CHLN), a synthetic derivative of chlorophyll, was assayed in the replication of poliovirus (PV‐1) and bovine herpesvirus (BoHV‐1) in HEp‐2 cell cultures. Methods and Results: Virucidal activity of CHLN was evaluated and the time‐of‐addition assay was performed as follows: before the infection (−1 and −2 h), at the time of the infection (0 h) and after the infection (1 and 2 h). Plaque reduction assay (PRA) showed that CHLN inhibited BoHV‐1 and PV‐1 infection and the 50% inhibitory concentrations (IC50) against BoHV‐1 and PV‐1 infection were 8·6 and 19·8 μg ml−1, respectively. The time‐of‐addition study demonstrated that the CHLN was effective inhibiting viral replication in 51% and 66·5% for PV‐1 and BoHV‐1, respectively, at the highest concentration of 20·0 μg ml−1, when added during the infection. The directed effect of CHLN on viral strains demonstrated an inhibition of 62% and 66·4% for PV‐1 and BoHV‐1, respectively, by PRA. Conclusions: These results demonstrated that CHLN could be used as an antiviral suggesting directed activity on virus particles and on virus‐receptor sites to BoHV. For poliovirus, CHLN also demonstrated virucide activity, moreover, showed to inhibit early steps of the replication cycle. Significance and Impact of the Study: CHLN demonstrated promising selectivity index for both virus strains; therefore, it can be used for the development of an antiviral agent.
ResumoA clorofilina (CHLN), derivado sintético da clorofila com atividade antimutagênica, foi analisada quanto a sua atividade antiviral para o poliovírus em culturas de células HEp-2. A droga foi avaliada quanto às atividades virucida, profilática e terapêutica na multiplicação do poliovirus em culturas de células HEp-2, nas concentrações de 0,5 e 2,5 µg/mL. A inibição do título viral e a reação de imunofluorescência foram utilizadas para avaliação. A CHLN inibiu a multiplicação do poliovírus nos três protocolos de tratamento, porém foi mais efetiva no tratamento virucida inibindo em 95,7% a multiplicação viral na concentração de 2,5 µg/mL. A CHLN reduziu o número de células infectadas com fluorescência específica, nos tratamentos virucida, e terapêutico, 8h e 10h pós-infecção, nas duas concentrações (0,5 e 2,5 µg/mL) . Sugere-se que a CHLN tem uma ação direta na partícula viral ou provavelmente age nos estágios iniciais da multiplicação do poliovirus. Palavras-chave: Clorofilina. Poliovírus. Antiviral. Cultura de células. AbstractChlorophyllin (CHLN), a semisynthetic derivative of chlorophyll with antimutagenic properties, was assayed for its antiviral effect on the replication of poliovirus in cell culture. The drug was tested for the virucide, prophylactic and therapeutic activities on the replication of the poliovirus in HEp-2 cells cultures, at concentrations of 0.5 and 2.5 µg/mL. Virus titration and an indirect immunofluorescence test were used for the evaluation. The CHLN inhibited poliovirus replication in all treatment protocols; however, it was more effective on virucide treatment, with a 95.7% reduction in viral multiplication at concentration of 2.5 µg/mL. CHLN reduced the number of specifically fluorescent infected cells in both virucide and therapeutic treatments, 8h and 10h post-infection, at both concentrations (0.5 and 2.5 µg/ mL). It is suggested that CHLN either has a direct action on the virus particles or acts on the initial stage of the poliovirus replication.
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