Additive Effects of Water-Soluble Propolis (Greit 120) and Human Interferon Alfa (HuIFN-αN3) against Influenza Viruses in Vitro

Influenza virus affects the respiratory tract in humans causing a range of distinct manifestations including fever, nasal secretions, cough, headaches, muscle pain and pneumonia, which could become violent and severe. It was found that influenza A viruses remain resistant to amantadine and rimantadin with high level of oseltamvir resistance. Therefore, there is a need for constant improvement of drugs active against resistant influenza viruses. Propolis has anti-influenza activity both in vitro and in vivo. Human leukocyte interferon (HuIFN-αN3) is a multi- subtype protein that displays an antiviral activity against influenza virus. In this study we elucidated the anti-influenza activity of the mixes of water-soluble propolis (WSP) (Greit 120) and HuIFN-αN3 at different ratios. Greit 120 polyphenols, total phenol acids and bioflavonoid were characterized by HPLC-UV-ESI- MS504971 and HuIFN-αN3 by reverse-phase high- performance liquid chromatography (RP-HPLC). Influenza A and B viruses were separately added to the LLC-MK2 cells treated with WSP (Greit 120) and HuIFN-αN3 alone or in proportions 1:1, 1:2 and 2:1. Plates were incubated and cytopathic effect was determined. The best results (ID50) were obtained with the mix of 10% WSP and HuIFN-αN3 in proportion 1:2, showing ID50 at 12 ± 0.2 μg/mL and 19 ± 0.6 μg/mL for influenza A and B viruses, respectively. When comparing anti- influenza activity of WSP (Greit 120)/HuIFN-αN3 with that of ribavirin, it was found that 1:2 was the optimal ratio for WSP (Greit 120)/HuIFN-αN3 (0.5 and 0.6 for influenza A and B, respectively). This new formulation of WSP (Greit 120) and HuIFN-αN3, showing better anti-Influenza activity, will definitely improve its application in flu infections.