Analysis of virucidal activity of standardized Propolis extracts against enveloped (i.e. coronaviruses) and non-enveloped RNA viruses

The purpose of this study was to determine the virucidal activity of Propolis M.E.D. (Multi Dinamic Extraction) ® preparation against different RNA viruses. The virucidal effects of this Propolis preparation were evaluated on enveloped viruses [namely, vesicular stomatitis virus (VSV), feline coronavirus (FCoV)-II and human coronaviruses (HCoV-229E and HCoV-OC43)] and a naked virus [namely, encephalomyocarditis virus, (EMCV)]. To examine virucidal activity of the Propolis M.E.D.® preparation prepared by B Natural S.r.l. (Milan, Italy), each virus was exposed at this propolis extract at different times of contact (5’ – 15’ – 30’). Results indicated that Propolis MED extract inhibited VSV titer just after 5’ time of contact with virus (viral titer reduction >99.9%). Furthermore, Propolis extract does not inhibit the infectivity of EMCV but exhibits significant virucidal activity against HCov-OC43, HcOV-229E, and FCoV-II. Specifically, the exposure to Propolis MED extract caused a reduction of FCoVII infectivity of 90% and >99.9% after 5’ and 15’ of exposure respectively. Moreover, Propolis Med extract has a potent virucidal activity against hCoV-OC43 and hCoV-229E (viral titer reduction >99.9% after 30’ time exposure). These results indicated that the Propolis MED extract exhibits a strong and a rapid virucidal activity against enveloped RNA viruses, including different types of coronaviruses.