In vitro virucidal activity of Echinaforce®, an Echinacea purpurea preparation, against coronaviruses, including common cold coronavirus 229E and SARS-CoV-2

Abstract

Background: Coronaviruses (CoVs) were long thought to only cause mild respiratory and gastrointestinal symptoms in humans but outbreaks of Middle Eastern Respiratory Syndrome (MERS)-CoV, Severe Acute Respiratory Syndrome (SARS)-CoV, and the recently identified SARS-CoV-2 have cemented their zoonotic potential and their capacity to cause serious morbidity and mortality, with case fatality rates ranging from 4 to 35%. Currently, no specific prophylaxis or treatment is available for CoV infections.Therefore we investigated the virucidal and antiviral potential of Echinacea purpurea (Echinaforce®) against human coronavirus (HCoV) 229E, highly pathogenic MERS- and SARS-CoVs, as well as the newly identified SARS-CoV-2, in vitro.Methods: To evaluate the antiviral potential of the extract we pre-treated virus particles and cells and evaluated remaining infectivity by limited dilution. Furthermore, we exposed cells to the extract after infection to further evaluate its potential as a prophylaxis and treatment against coronaviruses. We also determined the protective effect of Echinaforce® in re-constituted nasal epithelium.Results: In the current study, we found that HCoV-229E was irreversibly inactivated when exposed to Echinaforce® at 3.2mg/ml IC50. Pre-treatment of cell lines, however, did not inhibit infection with HCoV-229E and post-infection treatment had only a marginal effect on virus propagation at 50 mg/ml. However, we did observe a protective effect in an organotypic respiratory cell culture system by exposing pre-treated respiratory epithelium to droplets of HCoV-229E, imitating a natural infection. The observed virucidal activity of Echinaforce® was not restricted to common cold coronaviruses, as both SARS-CoV-1 and MERS-CoVs were inactivated at comparable concentrations. Finally, the causative agent of COVID-19, SARS-CoV-2 was also inactivated upon treatment with 50ug/ml Echinaforce®.Conclusions: These results show that Echinaforce® is virucidal against HCoV-229E, upon direct contact and in an organotypic cell culture model. Furthermore, MERS-CoV and both SARS-CoV-1 and SARS-CoV-2 were inactivated at similar concentrations of the extract. Therefore we hypothesize that Echinacea purpurea preparations, such as Echinaforce®, could be effective as prophylactic treatment for all CoVs due to their structural similarities.

Prophylaxis for COVID-19: a systematic review

“…This includes a focus on new candidates. Apart from the candidates identified in this review, other molecules cited in the published literature and in the media as possible prophylactic candidates include existing herbal extracts such as Echinacea [39,40], nicotine [41] and new molecules including PAC-MAN (prophylactic antiviral CRISPR in human) for viral inhibition [42] and DARPin as well as multitarget binding neutralizing proteins [43]. The underrepresentation of new molecules in ongoing RCTs is likely in part due to the relative novelty of this virus and the necessary time lag to develop new molecules before testing them in clinical trials.…”

Transcending Pandemics: Conceptualising the Centrality of Communication in Fostering Community Resilience

“…The coronaviruses are not new with seven already identified to be infectious to human. We are living and continuously adapting to coronaviruses HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU1, which causes the common cold (Signer et al, 2020). We have endured through two pandemics related to coronaviruses, with SARs-CoV identified in 2002 as the cause of severe acute respiratory syndrome (SARS) and MERS-CoV identified in 2012 as the cause of Middle East respiratory syndrome (MERS) (Paules et al, 2020).…”

Review of studies on SARS-CoV-2 infection inhibitors

“…In in vitro studies on cell lines it was observed that the antiviral effect of Echinacea extracts is limited only to the phases before the virus enters the host cell. The putative mechanism of action of the extracts is based on the interaction with the structural proteins of the viral glycoprotein S or the membrane protein M; therefore, the extracts may play a significant role in protection against infection as prophylactic agents [60].…”