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Screening of the antiviral and virucidal activities of ethanol extracts from plants endemic to the Republic of Korea revealed the inhibitory activity of a 70% ethanol extract of the whole plant of A. pseudoglehnii (APE) against influenza virus infection. Two chlorophyll derivatives, ethyl pheophorbides a and b, isolated as active components of APE, exerted virucidal effects with no evident cytotoxicity. These compounds were effective only under conditions of direct incubation with the virus, and exerted no effects on the influenza A virus (IAV) surface glycoproteins hemagglutinin (HA) and neuraminidase (NA). Interestingly, virucidal activities of ethyl pheophorbides a and b were observed against enveloped but not non-enveloped viruses, suggesting that these compounds act by affecting the integrity of the viral membrane and reducing infectivity. [ABSTRACT FROM AUTHOR]

We previously reported that the ethyl acetate (EtOAc) fraction of a 70% ethanol extract of Elaeocarpus sylvestris (ESE) inhibits varicella-zoster virus (VZV) and human cytomegalovirus (HCMV) replication in vitro. PGG (1,2,3,4,6-penta-O-galloyl-ß-D-glucose) is a major chemical constituent of the EtOAc fraction of ESE that inhibits VZV but not HCMV replication. In this study, we comprehensively screened the chemical compounds identified in the EtOAc fraction of ESE for potential antiviral properties. Among the examined compounds, quercetin and isoquercitrin displayed potent antiviral activities against both VZV and HCMV with no significant cytotoxic effects. Both compounds strongly suppressed the expression of VZV and HCMV immediate–early (IE) genes. Our collective results indicated that, in addition to PGG, quercetin and isoquercitrin are bioactive compounds in the EtOAc fraction of ESE that effectively inhibit human herpesvirus replication. [ABSTRACT FROM AUTHOR]