Landscape Analysis of Quercetin: A Potential Candidate Against SARSCoV- 2

Abstract: Fruit, vegetables, and green tea contain quercetin (a flavonoid). Some of the diet's most significant sources of quercetin are apples, onions, tomatoes, broccoli, and green tea. Antioxidant, anticancer, anti-inflammatory, antimicrobial, antibacterial, and anti-viral effects have been studied of quercetin. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus, ribonucleic acid (RNA) polymerase, and other essential viral life-cycle enzymes are all prevented from entering the body by quercetin. Despite extensive in vitro and in vivo investigations on the immune-modulating effects of quercetin and vitamin C treatment. 3-methyl-quercetin has been shown to bind to essential proteins necessary to convert minus-strand RNA into positive-strand RNAs, preventing the replication of viral RNA in the cytoplasm. Quercetin has been identified as a potential SARS-CoV-2 3C-like protease (3CLpro) suppressor in recent molecular docking studies and in silico assessment of herbal medicines. It has been demonstrated that quercetin increases the expression of heme oxygenase-1 through the nuclear factor erythroid-related factor 2 (Nrf2) signal network. Inhibition of heme oxygenase-1 may increase bilirubin synthesis, an endogenous antioxidant that defends cells. When human gingival fibroblast (HGF) cells were exposed to lipopolysaccharide (LPS), inflammatory cytokine production was inhibited. The magnesium (Mg+2) cation complexation improves quercetin free radical scavenging capacity, preventing oxidant loss and cell death. The main objective of this paper is to provide an overview of the pharmacological effects of quercetin, its protective role against SARS-CoV-2 infection, and any potential molecular processes.