Quercetin as a potential nutraceutic against coronavirus disease 2019 (COVID-19)

Abstract

Abstract Introduction: The coronavirus disease 2019 (COVID-19) is a viral disease that affects several human organs and systems. Preventive or prophylactic treatments are specifically useful in emerging infectious diseases such as COVID-19 because they reduce the need for hospitalization and public health spending. Although the SARS-CoV-2 preventive effect of several therapeutic agents (e.g., hydroxychloroquine/chloroquine, remdesivir, lopinavir, and ritonavir) has been extensively evaluated, none of them have demonstrated significant clinical efficacy. Method: We aim to address and discuss the recently published studies on the chemoprophylactic potential of quercetin against SARS-CoV-2. A literature search was carried out on different databases, such as PubMed/MEDLINE, Scielo, Scopus, Web of Science, Cochrane Library, and Clinical Trials.gov. Studies that report the effect of quercetin against SARS-CoV-2 or other types of coronaviruses were included and critically evaluated. Results: Studies have shown that quercetin, an FDA-approved flavonoid used as an antioxidant and anti-inflammatory agent, inhibits the entry of coronavirus (SARS-CoV) into the host cell. Moreover, an in silico study showed that quercetin is a potent inhibitor of the SARS-CoV-2 main protease (Mpro), suggesting that this flavonoid is also active against COVID-19. Conclusions: Because quercetin might prevent and lessen the duration of SARS-CoV-2 infections, it is plausible to assume that the prophylactic use of this flavonoid produces several clinical benefits. However, this preliminary evidence needs to be confirmed by in vitro assays and, posteriorly, in randomized clinical trials.

Keywords

• Quercetin
• Nutraceutic
• Coronavirus
• COVID-19
• SARS-CoV-2