BioVale QUERCETINA

Documentation

URINARY SYSTEM BENEFITS

IMMUNE SYSTEM BENEFITS

Preventing the flu with the cranberry Oximacro® – Important discovery of the Biologists of the University of Turin | University of Turin

(PDF) Antiviral properties of cranberry (Vaccinium macrocarpon Aiton) against Herpes simplex and Influenza (H1N1)

ANTIVIRAL ACTIVITY AGAINST INFLUENZA (H1N1)

Type A and type B influenza viruses (IAV, IBV) are major pathogens widespread in human populations and are responsible for seasonal epidemics and pandemics. Annual influenza epidemics cause 3-5 million cases of serious diseases worldwide and up to half a million deaths among high-risk groups, with an even greater impact in developing countries. Defense against influenza virus infections (IV) still poses several challenges. The current antiviral arsenal against influenza viruses is indeed limited; therefore, the development of new effective anti-influenza strategies against antigenically different viruses is an urgent priority. Oximacro® inhibits the replication of influenza A and B viruses (IAV, IBV) in vitro due to its high content of proanthocyanidins type A dimers and trimesters (PAC-A).

Oximacro® and its PAC-A inhibit IAV and IBV replication

Oximacro® inhibits the replication of IAV and IBV in MDCK cells in a concentration-dependent manner. IC50 values are 4.5 ± 0.2 μg/ml for IAV and 4.5 ± 0.5 μg/ml for IBV, respectively. The 50% cytotoxic concentration (CC50) is 141 ± 0.8 μg/ml, indicating that the antiviral activity of Oximacro® did not result from non-specific cytotoxicity. The selectivity index for IAV and IBV (CC50/IC50) is therefore 31.1 and 31.3 respectively.

Also against the influenza virus ONLY Oximacro® PAC-A have antiviral action

To identify the chemical fraction of Oximacro® responsible for its inhibitory activity, antiviral quantifications with purified fractions obtained by fractionation of Oximacro® were performed (see above). The analysis of the anti-IV activity of the fractions identified fractions 3 and 4 as having inhibitory activity against IAV and IBV, thus indicating that the components responsible for the antiviral activity of Oximacro® are only and exclusively PAC-A.

Oximacro® acts in the early stages of the influenza virus reproduction cycle

To understand the mechanism of action of Oximacro®, MDCK cells have been infected with IAV or IBV in the presence of different concentrations of Oximacro® for 2 hours at 4°C, so as to allow the attack of IV particles, but not their entry into the target cells. Oximacro® inhibited the attack of IAV and IBV in a concentration-dependent manner (Figure A). Subsequently, to investigate the inhibitory activity of Oximacro® on IV INLET, monolayers of MDCK were infected with IV at 4°C for 2 hours to allow viral attack but not entry. Different concentrations of Oximacro® were then added and the infected cultures were incubated at 37°C for 2 hours to allow adsorbed IV particles to enter. Oximacro® prevented the entry of IAV and IBV in a concentration-dependent manner (Figure B). These results show that Oximacro® is capable of interfering with both viral adhesion and virus entry into cells, suggesting its suitability as an early action inhibitor of influenza virus replication.

Oximacro® interferes with influenza virus hemagglutinin

Influenza virus hemagglutininin (HA) is responsible for both adhesion and entry of the virus by mediating both initial interaction with cellular receptors containing sialic acid and fusion between endosomal membranes and the viral envelope. Oximacro® is able to interact with HA in a concentration- and time-dependent manner and interactions between Oximacro® and HA can impede its viral adhesion and virus entry functions by underlying the overall antiviral activity of Oximacro®. To further identify the mechanism of interaction between HA and Oximacro® PAC-A, in silico docking simulations were performed. Using the crystalline structure of HA (A / Puerto Rico / 8/1934, PDB ID: 1RU7) of the tested influenza virus strain, docking analysis revealed that Oximacro® PAC-A dimers first bind to the inner grooves of the HA structure (Figure A, left panel), and then to the surface of the HA structure (Figure A, right panel). The best bonding pose is shown in Figure B, where HA residues (PHE 299, TRP 234 and ASN 210) forming hydrogen bonds with Oximacro® PAC-A dimers are highlighted.

Overall, the described mechanism of action of Oximacro® against the influenza virus supports its potential application as a support for influenza infections.

Please refer to the document for a full description of the methods and results:

LUGANINI, A., TERLIZZI, M.E., CATUCCI, G., GILARDI, G., MAFFEI, M.E., GRIBAUDO, G. (2018)
The cranberry extract Oximacro® exerts in vitro virucidal activity against influenza virus by interfering with hemagglutinin. 
Frontiers in Microbiology, 9: 1826