Antiviral effect of an essential oil combination derived from three aromatic plants (Coridothymus capitatus (L.) Rchb. f., Origanum dictamnus L. and Salvia fruticosa Mill.) against viruses causing infections of the upper respiratory tract

An essential oil combination based on three aromatic plants (Coridothymus capitatus L., Origanum dictamnus L and Salvia fruticosa Mill), in extra-virgin olive oil, herein denoted as CAPeo - Cretan Aromatic Plant essential oil) has been shown to reduce the duration and severity of symptoms of patients with upper respiratory tract viral infections. In this study the authors tested whether the combinatorial CAPeo exhibited a direct antiviral activity against a wide range of respiratory viruses in vitro. The study revealed a remarkable antiviral activity of the essential oil combination against influenza A/H1N1 virus strains, influenza B and human rhinovirus 14 (HRV14) whereas no viral inhibition was found for influenza A/H3N2, Respiratory Syncytial Virus (RSV) and Adenovirus 5. Both in influenza A/H1N1 and HRV14, replication cycle and progeny virus production were significantly decreased after the treatment with CAPeo. Pre-treatment with the plant essential oil combination demonstrated that CAPeo exerts its antiviral activity after A/H1N1 or HRV14 entry in host cells, whereas it confers a preventive reactivity against RSV. Furthermore, CAPeo resulted in a defective trafficking of influenza A Nucleoprotein (NP), suggesting NP as a valid target of this extract. It was concluded that the essential oil combination possessed antiviral activity and had the potential to be used as an herbal agent against influenza viruses and rhinovirus.