Flavonoids: A complementary approach to conventional therapy of COVID-19?

Abstract

COVID-19, the highly contagious novel disease caused by SARS-CoV-2, has become a major international concern as it has spread quickly all over the globe. However, scientific knowledge and therapeutic treatment options for this new coronavirus remain limited. Although previous outbreaks of human coronaviruses (CoVs) such as SARS and MERS stimulated research, there are, to date, no antiviral therapeutics available that specifically target these kinds of viruses. Natural compounds with a great diversity of chemical structures may provide an alternative approach for the discovery of new antivirals. In fact, numerous flavonoids were found to have antiviral effects against SARS-and MERS-CoV by mainly inhibiting the enzymes 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro). In this review, we specifically focused on the search for flavonoids, polyphenolic compounds, which are proven to be effective against human CoVs. We therefore summarized and analyzed the latest progress in research to identify flavonoids for antiviral therapy and proposed strategies for future work on medicinal plants against coronaviruses such as SARS-CoV-2. We discovered quercetin, herbacetin, and isobavachalcone as the most promising flavonoids with anti-CoV potential.

Polyphenols as promising biologically active substances for preventing SARS-CoV-2: A review with research evidence and underlying mechanisms

“…The hydroxyl group of flavonoids at 7-position looks important to bind at the binding site against 3-chymotrypsin-like protease (3CLpro), and papain-like protease (PLpro). Flavonoids as a vast reservoir of therapeutically active constituents as antiviral candidates against RNA viruses, adopted from Rasouli et al (2017) , Solnier et al (2020) , and Pillaiyar et al (2020) . …”

Identification of Potential Flavonoid Inhibitors of the SARS-CoV-2 Main Protease 6YNQ: A Molecular Docking Study

“…Interestingly, many bioactive compounds derived from plants that are known to exert some antiviral effects, have attracted researchers’ attention, with a large panel of these compounds under evaluation for SARS-CoV-2 12 , 13 . Among them, flavonoids have been revealed as the most promising antiviral agents [ 14 ] . Flavonoids are a large class of food additives that have a positive impact on health and which have been extensively evaluated against a wide range of DNA and RNA viruses.…”

The Impact of Polyphenols-Based Diet on the Inflammatory Profile in COVID-19 Elderly and Obese Patients

“…Indeed, a Phase 2 randomized double-blind placebo-controlled study aims to explore the effectiveness of a commercial plant polyphenols supplemented with vitamin D3 in a set of 200 mild COVID-19 patients (NCT04400890). Moreover, it has been suggested that quercetin, a well-characterized antioxidant, anti-inflammatory and immunomodulatory compound would be a good option in COVID-19 therapeutics ( Solnier and Fladerer, 2020 ). Currently, there are five clinical trials evaluating the adjuvant benefits of quercetin (alone or in combination) in patients with COVID-19 ( Table 1 ) The antiviral properties of resveratrol have also been shown both in vitro and in vivo ( Marinella, 2020 ).…”