Furthermore anti viral herbal extracts frequently exhibit multiple bioactivities, and this could enable their use at relatively low doses free copy of the active compounds, possibly acting in synergy, while at the same time providing a relatively safe drug with few side effects. Needless to say, acquisition of resistance to herbal compounds is also a potential problem. consequently this would need to be evaluated, although if multiple bioac tive compounds were involved, this would substantially reduce the risk of resistant viruses emerging. We recently reported the anti viral properties of a stand ardized preparation of Echinacea purpurea, which has become a very popular herbal remedy for the symptoms of colds and flu.

In addition to pos sessing potent virucidal activity against Inhibitors,Modulators,Libraries several membrane containing viruses, Inhibitors,Modulators,Libraries including H3N2 type IV, at the recom mended dose for oral consumption, the preparation also effectively reversed virus induced pro inflammatory responses in cultured epithelial cells. Some Echina cea derived preparations also possess selective anti bacte rial and immune modulation activities that might also contribute to their beneficial properties. However, our studies also indicated that anti viral and cytokine inhibitory properties vary widely among different Echina cea species and components. thus it is important to carry out research on Echinacea preparations that have been standardized and chemically Inhibitors,Modulators,Libraries characterized.

The objective of the present study was to investigate the anti IV activity in more detail, Inhibitors,Modulators,Libraries and to elucidate possible mechanisms of action on a variety of IV strains, with emphasis on a human isolate of the H5N1 type HPAIV, and to evaluate the potential for emer gence of resistant strains, in comparison with oseltamivir. Results Echinaforce and Virus Concentration Inhibitors,Modulators,Libraries We reported previously that at concentrations up to 1. 6 mgml the EF extract showed no apparent cytotoxic effects, according to trypan blue staining, MTT assays, or microscopic examina tion, data not shown]. However at concentrations of 1. 6 ?gml 99% inactivation of H3N2 type IV was achieved. The degree of inactivation depended on the virus dose, as might be expected. MIC100 values increased from 0. 32 ?gml for 102 PFUml virus, up to 7. 5 ?gml for 105 PFUml. In order to exclude the possibility that the virucidal effect might be subtype specific or related only to human IV, we analyzed the effect of EF in non toxic concentrations on a human isolate of a H5N1 type HPAIV.

Virus yield reduction assays were carried out with KAN 1, which had been pre incubated with various concentrations more of EF, from 0. 1 to 50 ?gml. At the highest concen tration the yield was reduced by more than 3 log10. Fur thermore we tested the inhibitory effect of EF on human H1N1 type and a H7 type HPAIV and obtained comparable results, indicating that EF affects not only human IV but also both types of HPAIV.