title: In vitro evaluation of synergistic inhibitory effects of neuraminidase inhibitors and methylglyoxal against influenza virus infection.
abstract: OBJECTIVE
  Influenza 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.
  
  
  METHODS
  MDCK 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.
  
  
  RESULTS
  MGO 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 ∼1/100(th) of their single usage. A synergistic effect of MGO and oseltamivir was also observed against oseltamivir-resistant virus.
  
  
  CONCLUSIONS
  Our 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.
authors.affiliation: Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Siriwan
authors.initials: S
authors.lastname: Charyasriwong
authors.affiliation: Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Ratika
authors.initials: R
authors.lastname: Rahmasari
authors.affiliation: Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Matsunaga
authors.affiliation: Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan; Central Research Center, AVSS Corporation, Nagasaki, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Haruyama
authors.affiliation: Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan; Central Research Center, AVSS Corporation, Nagasaki, Japan. Electronic address: nobnob@nagasaki-u.ac.jp.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D004285:Dogs; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects; D053125:Influenza A Virus, H5N2 Subtype / Q000187:drug effects; D009980:Influenza A virus / Q000187:drug effects*; D020128:Inhibitory Concentration 50; D061985:Madin Darby Canine Kidney Cells; D009439:Neuraminidase / Q000037:antagonists & inhibitors*; D009976:Orthomyxoviridae Infections / Q000188:drug therapy / Q000821:virology; D053139:Oseltamivir / Q000494:pharmacology*; D011765:Pyruvaldehyde / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D053139:Oseltamivir; D011765:Pyruvaldehyde; D009439:Neuraminidase
keywords: Anti-influenza viral drug; Influenza virus; Manuka honey; Methylglyoxal; Neuraminidase inhibitors; Synergistic effect