In Vitro Evaluation of Synergistic Inhibitory Effects of Neuraminidase Inhibitors and Methylglyoxal Against Influenza Virus Infection

Background and AimsInfluenza virus infections are serious public health concerns worldwide that cause considerable mortality and morbidity. Moreover, the emergence of resistance to anti-influenza viral agents underscores the need to develop new anti-influenza viral agents and novel treatment strategies. Recently, we identified anti-influenza viral activity of manuka honey. Therefore, we hypothesized that methylglyoxal (MGO), a key component of manuka honey, may impart anti-influenza viral activity. The aim of this study was to evaluate the anti-influenza viral activity of MGO and its potential in combination treatments with neuraminidase (NA) inhibitors.MethodsMDCK cells were used to evaluate anti-influenza viral activity. To evaluate the mechanism of MGO, plaque inhibition assays were performed. The synergistic effects of MGO and viral NA inhibitors were tested.ResultsMGO inhibited influenza virus A/WSN/33 replication 50% inhibitory concentration = 240 ± 190 μM; 50% cytotoxic concentration = 1.4 ± 0.4 mM; selective index (SI) = 5.8, which is related to its virucidal effects. Moreover, we found that MGO showed promising activity against various influenza strains. A synergistic effect was observed by a marked increase in SI of NA inhibitors at ∼1/100th of their single usage. A synergistic effect of MGO and oseltamivir was also observed against oseltamivir-resistant virus.ConclusionsOur results showed that MGO has potent inhibitory activity against influenza viruses and also enhanced the effect of NA inhibitors. Thus, the co-administration of MGO and NA inhibitors should be considered for treatment of influenza virus infections.