Phytochemicals: Potential Lead Compounds for COVID-19 Therapeutics

Coronavirus Disease 2019 (COVID-19) is a global pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2). The rising number of cases of this highly transmissible infection has pressed for the urgent need to find effective therapeutics. The life cycle of SARS-CoV-2 includes the viral entry, viral replication, viral assembly and release. The symptoms associated with viral infection often leads to fatal outcome with pneumonia, myocarditis, acute respiratory distress syndrome, hypercoagulability, and/or multi-organ failure. Recent studies have reported that phytochemicals such as emodin, epigallocatechin gallate, and berberine could, albeit modestly, inhibit different stages of SARS-CoV-2 life cycle. The phytochemicals have been shown to disrupt viral infection and replication by blocking viral-surface spike protein binding to entry receptor angiotensin-converting enzyme (ACE2), inhibiting viral membrane fusion with host cells, inhibiting RNA-dependent RNA polymerase involved in viral replication, and/or pathological host- responses in vitro. The focus of this review is to evaluate the efficacies of these phytochemicals on inhibiting SARS-CoV-2 viral infection, growth, or disease progression as well as to provide a perspective on the potential use of these phytochemicals in the development of novel therapeutics against SARS-CoV-2