QUERCETIN

QUERCETIN

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the ongoing global pandemic known as COVID-19. Based on the potential antiviral role of quercetin, and on its described anti-blood clotting, anti-inflammatory and antioxidant properties, we hypothesize that subjects with mild COVID-19 treated with Quercetin Phytosome® (QP), a novel bioavailable form of quercetin, may have a shorter time to virus clearance, a milder symptomatology, and higher probabilities of a benign earlier resolution of the disease.

The development of an effective adaptive immune response can limit the SARS CoV-2 viral infection, but the uncontrolled activation of innate immune cells results in an aggressive hyperinflammatory response with the release of an excessive amount of pro inflammatory cytokines in a process known as “cytokine storm”. The cytokine storm leads to increased risk of vascular hyperpermeability, acute respiratory distress syndrome (ARDS), multiorgan failure, and eventually death when the high cytokine concentrations are unabated over time. The cytokine storm is believed to be the major underlying cause of large number of COVID-19 deaths. Therefore, a timely intervention of well tolerated agents that can modulate or prevent the cytokine storm and the viral replication imbalance are potentially the strategies to prevent the severe COVID-19 disease development. Quercetin, a flavonoid with an excellent safety profile, has powerful antioxidant, anti-inflammatory, immunomodulatory and antiviral properties, and can potentially help in the early stage of SARS-CoV-2 viral infection to prevent disease development and progression.

As for most of polyphenols, the practical use of quercetin is limited by its low solubility and reduced oral absorption. (Di Pierro, 2021).

Quercetin should be combined with Bromelain to increase its bioavailability and thereby its efficacy.

The major druggable targets of SARS‐CoV‐2 include 3‐chymotrypsin‐like protease (3CLpro), papain‐like protease (PLpro), RNA‐dependent RNA polymerase, and spike (S) protein. Quercetin inhibits 3CLpro and PLpro with a docking binding energy corresponding to −6.25 and −4.62 kcal/mol, respectively. Quercetin has a theoretical, but significant, capability to interfere with SARS‐CoV‐2 replication, with the results showing this to be the fifth best compound out of 18 candidates. On the basis of the clinical COVID‐19 manifestations, the multifaceted aspect of quercetin as both anti-inflammatory and thrombin‐inhibitory actions, should be taken into consideration. (Derosa, 2020).

Reference:

(Di Pierro, 2021). Di Pierro F, Iqtadar S, Khan A, et al. Potential Clinical Benefits of Quercetin in the Early Stage of COVID-19: Results of a Second, Pilot, Randomized, Controlled and Open-Label Clinical Trial. Int J Gen Med. 2021;14:2807-2816. Published 2021 Jun 24. doi:10.2147/IJGM.S318949 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8238537/

(Derosa, 2020). Derosa G, Maffioli P, D’Angelo A, Di Pierro F. A role for quercetin in coronavirus disease 2019 (COVID-19). Phytother Res. 2021 Mar;35(3):1230-1236. doi: 10.1002/ptr.6887. Epub 2020 Oct 9. PMID: 33034398; PMCID: PMC7675685. https://pubmed.ncbi.nlm.nih.gov/33034398/