Natural Products in Mitigation of SARS CoV Infections

Severe acute respiratory syndrome (SARS) is a critical respiratory disease caused by coronaviruses (CoV). The available antiviral agents or host-specific antiinflammatory therapies are the principal treatment modalities, with drug-repurposing as the most viable approach to timely tackle the CoV pandemic. Though these approaches are successful to some extent in reducing the mortality rate, however, it is too far to see a complete escape from the current SARS CoV-2 pandemic. Plants are the primary source of diet, dietary supplements, botanical drugs, and natural products (NPs). It has been well accepted and proved via several scientific studies that plant-based therapies play a vital role in managing such infections. The faulty immune system (compromised innate immunity or aberrant immune activation) determines the severity of the respiratory distress in CoV-2 infected patients. Natural products intervene at various stages of the virus replication cycle, including inhibition of virus entry into the host cells, inhibition of serine/ cysteine proteases, RNA-dependent RNA polymerase (RdRp) or helicase. Besides, several natural products or plant-based dietary supplements have a unique ability to strengthen the immune system or alleviate the hyper-inflammatory condition. Many plant-based formulations, dietary supplements, and NPs are being investigated in clinical trials in CoV-2 infected patients, and few have already shown positive results. The review has unearthed several NP leads for medicinal chemistry programs as well as some having direct opportunity of repurposing in SARS CoV infections.