Respiratory viral infections continue to pose significant challenges, particularly for more susceptible and immunocompromised individuals. Nutraceutical strategies have been proposed as promising strategies to mitigate their impact and improve public health. In the present study, we developed a mixture of two hydroalcoholic extracts from the aerial parts of Echinacea purpurea (L.) Moench (ECP) and the cones of Humulus lupulus L. (HOP) that can be harnessed in the prevention and treatment of viral respiratory diseases. The ECP/HOP mixture (named ECHOPvir) was characterized for the antioxidant and cytoprotective properties in airway cells. Moreover, the immunomodulating properties of the mixture in murine macrophages against antioxidant and inflammatory stimuli and its antiviral efficacy against the PR8/H1N1 influenza virus were assayed. The modulation of the Nrf2 was also investigated as a mechanistic hypothesis. The ECP/HOP mixture showed a promising multitarget bioactivity profile, with combined cytoprotective, antioxidant, immunomodulating and antiviral activities, likely due to the peculiar phytocomplexes of both ECP and HOP, and often potentiated the effect of the single extracts. The Nrf2 activation seemed to trigger these cytoprotective properties and suggest a possible usefulness in counteracting the damage caused by different stressors, including viral infection. Further studies may strengthen the interest in this product and underpin its future nutraceutical applications.
Keywords: Nrf2; antioxidant; echinacea; herbal extracts; hop cones; host defences; immune system; influenza virus; respiratory infections; viruses.