Effects of chlorophyllin on replication of poliovirus and bovine herpesvirus in vitro.

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 (IC(50)) against BoHV-1 and PV-1 infection were 8.6 and 19.8 microg 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 microg 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.

Antiviral activity of aqueous and ethanol extracts and of an isolated polysaccharide from Agaricus brasiliensis against poliovirus type 1.

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.