What do red onion, capers and radicchio have in common? All of us know that they are vegetables, of course, but few may know that they all contain abundant amounts quercetin.
Quercetin, as we will see, has remarkable antioxidant, anti-inflammatory and anti-allergic properties and is virtually free of harmful side effects for humans.
It can be relatively easily adapted to develop an even more powerful synthetic molecule, thanks to its small size and the specific functional groups present in its chemical structure.
It has another non-negligible advantage: since it cannot be patented, anyone can use it as a starting point for new research.
What is it?
Quercetin is a flavonoid produced by the metabolism of some plants (horse chestnut, hawthorn, chamomile), but is also found in vegetables and fruits. It is used in the treatment of metabolic and inflammatory disorders and the main activity attributed to it is the antioxidant. Helps to reduce the formation of free radicals and pro-inflammatory substances. It is attributed vasoactive properties as it will increase the resistance of the capillaries.
Several studies show that quercetin has the following properties:
- reduction of endometrial tissue formation
- of cardiovascular protection
- anti-atherosclerotic agent by inhibiting LDL oxidation and consequent arterial endothelial damage
- antiviral (we’ll talk about that in relation to Covid-19 soon).
Quercetin is absorbed in the intestines and its metabolites are distributed from the liver to the various tissues of the body; in plasma it is bound to albumin. The availability of quercetin taken orally is uncertain; it appears to be better assimilated by the gut when taken with fats such as medium chain triglycerides. For this reason, it is important that any quercetin supplements contain lipid substances and that they are taken on a full stomach. Equally important, as well as obvious, is the consumption of vegetables and fruits. Finally, in addition to the above plants, it should be remembered that quercetin is found in cocoa, green tea and citrus fruits.
The antiviral property
And we come to the encouraging studies on the possible use of quercetin as an adjunct in the treatment of Covid-19.
In September 2020, the CNR published a press release to announce the discovery of an international study in which the Institute for Nanotechnology of the national research body participated: “Quercetin, a molecule of natural origin, acts as a specific inhibitor for the virus responsible for Covid-19, showing a destabilizing effect on 3CLpro, one of the fundamental proteins for the replication of the virus…”.
The result is the outcome of the research work carried out by Bruno Rizzuti from the Nanotechnology Institute of the National Research Council (Cnr-Nanotec) of Cosenza together with a group of researchers from Madrid and Zaragoza and was published in the prestigious journal International Journal of Biological Macromolecules.
Let’s move to Spain and listen to the doctor Olga Abianfrom the University of Zaragoza and first author of the publication: “In a first phase of work, the sensitivity of this protein to various temperature and pH conditions was studied with various experimental techniques: an important result because many groups are working on 3CLpro as a possible pharmacological target, based on the fact that it is highly conserved in all types of coronaviruses“.
Furthermore: “The most interesting part of this work is the experimental screening carried out on 150 compounds, through which quercetin was identified as an active molecule on 3 Clpro “, concluded Adrian Velazquez-Campoy of the University of Zaragoza, who led the research team and was already working on the search for protein inhibitors for the original SARS virus that caused the 2003 outbreak. “Quercetin reduces the enzymatic activity of 3 Clpro thanks to its destabilizing effect on the protein…“.
As they say in these cases “If they are roses they will bloom”.