ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has adversely affected humankind because it is the etiological agent of coronavirus disease 2019 (COVID-19), which has a high morbidity and mortality rate. Natural polyphenols present in plants, fruits, and vegetables have great potential to treat numerous viral diseases. Flavonoids, a group of polyphenols, due to their anti-inflammatory, antioxidant, and anticarcinogenic properties, act as lead bioactive components present in plants and foods obtained from plants. Numerous studies have investigated the treasure of flavonoids from different plant sources for the treatment of SARS-CoV-2. A great deal of research has proved that a diet full of flavonoids can alleviate inflammation and oxidative stress and, hence, reduce the severity of infection. Structural inhibition of SARS-CoV-2 proteins including the spike, main protease (3CLpro), envelope, RNA-dependent RNA polymerase, and papain-like protease (PLpro) by a variety of flavonoids has been highlighted by computational, structural, and in vitro biophysical analysis. Quercetin, kaempferol, epicatechin, rutin, and myricetin are eminent flavonoids and show immense potential to treat SARS-CoV-2. Hence, this chapter illustrates a diverse variety of flavonoids, their sources, relevant bioactive properties, and their mechanisms of action against SARS-CoV-2, along with recent investigations enumerating the potential of flavonoids to treat SARS-CoV-2 infection.
