Anti-viral properties and mode of action of standardized Echinacea purpurea extract against highly pathogenic avian Influenza virus (H5N1, H7N7) and swine-origin H1N1 (S-OIV)

Abstract

BackgroundInfluenza virus (IV) infections are a major threat to human welfare and animal health worldwide. Anti-viral therapy includes vaccines and a few anti-viral drugs. However vaccines are not always available in time, as demonstrated by the emergence of the new 2009 H1N1-type pandemic strain of swine origin (S-OIV) in April 2009, and the acquisition of resistance to neuraminidase inhibitors such as Tamiflu® (oseltamivir) is a potential problem. Therefore the prospects for the control of IV by existing anti-viral drugs are limited. As an alternative approach to the common anti-virals we studied in more detail a commercial standardized extract of the widely used herb Echinacea purpurea (Echinaforce®, EF) in order to elucidate the nature of its anti-IV activity.ResultsHuman H1N1-type IV, highly pathogenic avian IV (HPAIV) of the H5- and H7-types, as well as swine origin IV (S-OIV, H1N1), were all inactivated in cell culture assays by the EF preparation at concentrations ranging from the recommended dose for oral consumption to several orders of magnitude lower. Detailed studies with the H5N1 HPAIV strain indicated that direct contact between EF and virus was required, prior to infection, in order to obtain maximum inhibition in virus replication. Hemagglutination assays showed that the extract inhibited the receptor binding activity of the virus, suggesting that the extract interferes with the viral entry into cells. In sequential passage studies under treatment in cell culture with the H5N1 virus no EF-resistant variants emerged, in contrast to Tamiflu®, which produced resistant viruses upon passaging. Furthermore, the Tamiflu®-resistant virus was just as susceptible to EF as the wild type virus.ConclusionAs a result of these investigations, we believe that this standard Echinacea preparation, used at the recommended dose for oral consumption, could be a useful, readily available and affordable addition to existing control options for IV replication and dissemination.

Antiviral activity and possible mechanisms of action of pentagalloylglucose (PGG) against influenza A virus

“…Since many traditional medicinal plants have been reported to have strong antiviral activity [6,30,37], they offer a rich source for discovering novel antiviral compounds. In order to explore novel active compounds against IAV, we screened a number of natural compounds purified from different Chinese medicinal plants.…”

Potential of the Phytomedicine Echinacea in the Treatment of Pulmonary Infections and Bronchitis

“…Therefore, the actions of Echinaforce should be manifest during initial contact with the virus, that is, at the inception of infection, and also during transmission of virus from infected cells. Additional experiments showed that continuous passage of influenza A virus in cell cultures in the presence of EF did not result in the emergence of resistant strains, whereas in contrast, passing the virus through successive cultures in the presence of Tamiflu rapidly produced Tamiflu-resistance (Pleschka et al, 2009). Furthermore, Tamiflu-resistant virus remained fully susceptible to EF.…”

“…Recent detailed studies with the standardized preparation Echinaforce  (EF, comprising ethanol extracts of E. purpurea, 95% aerial parts plus 5% roots) revealed that this preparation was very active as a virucidal agent against several viruses with membranes, as indicated in Table 1. In addition to HSV-1 and respiratory syncytial virus, all tested human and avian strains of influenza A virus, as well as influenza B virus, were susceptible (Sharma et al, 2009a;Pleschka et al, 2009). In addition, rhinoviruses were also equally susceptible at the relatively high concentrations of EF recommended for oral consumption (Table 1).…”

Antiviral activity of the oseltamivir and Melissa officinalis L. essential oil against avian influenza A virus (H9N2)

“…Antiviral activity of some medicinal plants against influenza viruses such as green tea, pomegranate, licorice root, milk thistle, Echinacea purpurea, have been reported previously due to the safety and development of resistance by influenza viruses [9,25,30,32]. In the present study, for the first time the researchers demonstrated that lemon balm essential oil ingredients inhibit AVI (H9N2) proliferation and mechanism action of MOEO against AIV was evaluated at different steps of influenza virus replication cycle.…”