Interest in the antiviral activity of natural flavonoids has increased in the last decade due to the frequency of viral infections, particularly influenza infections, which affect several million people each year. Many flavonoids, in fact, show antiviral activity and could offer a promising option for the prevention and treatment of viral infections.
These substances are present in many foods of plant origin and can contribute to the homeostasis of the intestinal microbiota that, in turn, regulates the immune system. The molecular mechanisms underlying the effects of flavonoids are mainly related to the inhibition of the activity of viral enzymes: neuraminidase, Dna/Rna polymerase and protease. Therefore, a cocktail of flavonoids, selected for their efficacy in inhibiting different viral enzymes, could contribute to a more effective immune response, offering a complementary therapeutic option.
They are molecules present in many plant species. In our cells they play an important antioxidant action. This is a wide range of molecules subdivided for convenience in different subclasses that include flavones, flavanols, flavins, isoflavones and anthocyanins.
Studies conducted so far have shown that each molecule acts on multiple fronts of the viral infectious process, with a pleiotropic effect. The attention, over the years, has focused on derivatives of apigenin, quercetin, epigallocatechin gallate, naringenin: each of them acts either on viral replication, or on the assembly of the virion once penetrated into the cells. For this reason, the synergistic action is the most effective.
In particular, the derivatives of apigenin, a flavone that, with the addition of sugars, can give rise to other molecules such as vitexin, vitexin xyloside, vitexin rhamnoside: a real pool of antioxidants that defend us from physiological oxidative processes.
Each virus has its own peculiarities, and it is good to always evaluate which flavonoids are more active than others in the specific case. The best solution is always a cocktail, or calibrated mixtures that exploit the synergistic action of individual molecules. Often, in fact, the poor bioavailability of flavonoids can be overcome by a mixture that contains substances “permissive”, which facilitate the entry of other specific action on the virus. The same applies to the mix with antiviral drugs, whose action we have seen to be implemented by flavonoids.
The best vehicles to reach the target cells have proved to be liposomes and phytosomes, which facilitate the transport through the lipophilic cell membrane, with a single trick: to concentrate inside the vesicles the best cocktail of substances able to act on several fronts to block the virus, preventing it from infecting new cells.
The help of flavonoids is certainly important not to stress the immune system and give it time to intervene with specific antibodies, especially when it encounters unknown antigens, as in the case, for example, of Sars-coV-2. They can be the first line of defense until the immune system gets organized. Flavonoid-rich preventive therapy is seen as essential where diet is not sufficient.
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