Anti-influenza viral effects of honey in vitro: potent high activity of manuka honey.

Influenza viruses are a serious threat to human health and cause thousands of deaths annually. Thus, there is an urgent requirement for the development of novel anti-influenza virus drugs. Therefore, the aim of this study was to evaluate the anti-influenza viral activity of honey from various sources. Antiviral activities of honey samples were evaluated using MDCK cells. To elucidate the possible mechanism of action of honey, plaque inhibition assays were used. Synergistic effects of honey with known anti-influenza virus drugs such as zanamivir or oseltamivir were tested. Manuka honey efficiently inhibited influenza virus replication (IC50 = 3.6 ± 1.2 mg/mL; CC50 = 82.3 ± 2.2 mg/mL; selective index = 22.9), which is related to its virucidal effects. In the presence of 3.13 mg/mL manuka honey, the IC50 of zanamivir or oseltamivir was reduced to nearly 1/1000th of their single use. Our results showed that honey, in general, and particularly manuka honey, has potent inhibitory activity against the influenza virus, demonstrating a potential medicinal value.