A fascinating new study published in the Archives of Medical Research titled, “Anti-influenza Viral Effects of Honey In Vitro: Potent High Activity of Manuka Honey,” reveals that honey may actually provide a natural drug alternative to anti-flu drugs, but without the notorious side effects associated with this drug class which includes Tamiflu (oseltamivir).
The study tested a commonly researched H1N1 influenza strain known as A/WSN/3, infecting MadineDarby canine kidney (MDCK) cells with the virus, and then exposing them to various forms of honey, including manuka (L. scoparium), soba (F. esculentum; buckwheat), kanro (honeydew), acacia (R. pseudoacacia), and renge (A. sinicus).
The anti-influenza virus effects of the honey samples were evaluated by growing MDCK cells in 48-well plates and infecting them with influenza virus in the presence of 2-fold serially diluted honey samples. Two days after infection, the cells were fixed and stained in order to ascertain the degree to which they prevented the cytopathic effect (i.e., the degree to which influenza virus infection caused the cells to die and detach from the plate) of influenza virus.
The results of the study were represented pictorially in the figure below:
All tested honey samples suppressed viral infectivity in a dose-dependent manner, indicating their anti-viral activity, with manuka honey exhibiting the greatest potency.
The study also tested whether manuka honey is able to directly inhibit influenza virus growth through what is known as the plaque inhibition assay, as determined through the following 4 methods:
- Pretreatment of cells: Adding manuka to the cells for 1 h and subsequently washed out before viral infection.
- Pretreatment of virus: Mixing manuka with influenza virus suspension for 1 h before viral infection
- Treatment during infection: Adding manuka during virus adsorption for 1 h and subsequently washed out
- Treatment after infection: Adding manuka to the agarose gels
The most potent effect was exhibited with pretreatment of the virus itself, indicating manuka has potent virus-killing properties. Moderate reductions in plaque numbers were observed on treatment of cells with the honey during and after infection. The only method that did not demonstrate a growth inhibition was the pretreatment of cells.
Synergistic Effect of Honey with Conventional Anti-Viral Drugs
The study also looked at manuka honey’s synergistic properties in combination with conventional anti-viral drugs in the neuraminidase inhibitor class known as Relenza (zanamivir) and Tamiflu (oseltamivir). The researchers commented:
“A combined use of synergistically active antiviral compounds that have different mechanisms of action may provide advantages over single-agent treatments.”
The plaque inhibition assay protocal was reproduced, but this time the drugs were added to the honey mixture, with the result that manuka significantly increased the anti-viral effectiveness of both drug compounds.