Plant-derived Extracts and Bioactive Compounds against Coronavirus Progression: Preventive Effects, Mechanistic Aspects, and Structures

Coronaviruses (CoVs) are associated with several infectious outbreaks in humans, beginning with severe acute respiratory syndrome (SARS) in 2003 and Middle East respiratory syndrome (MERS) in 2012. Recently, the World Health Organization (WHO) announced the global outbreak of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 in December 2019. There are currently no natural or synthetic drugs that inhibit SARS-CoV2. Because of the COVID-19 outbreak, many people have returned to the use of complementary or traditional medicinal therapies for prophylaxis or treatment. Herbal extracts and their purified natural compounds provide a platform for the development of novel antiviral candidates. Effective drugs may be designed based on the chemical structure of natural compounds that exhibit potential effects. Researchers have primarily focused on 3-chymotrypsin-like protease (3CLpro), papain-like protease (PLpro), RNA-dependent RNA polymerase, and spike (S) proteins as drug targets for SARS-CoV. Furthermore, phylogenetic studies of the viral genome have provided evidence of a close similarity between SARS-CoV2 and SARS-CoV1. Here, we review the literature with respect to plant extracts from different families that have been examined for antiviral activity against coronavirus diseases and explore the underlying mechanisms. We also discuss the structures of promising natural compounds representing different categories that serve as SARS-CoV chemical inhibitors. Hopefully, this chapter will provide a valuable tool for scientists interested in developing effective naturally derived anti-SARS-CoV-2 drugs for the management of COVID-19 development and progression.

Keywords: Antiviral, Coronavirus, Outbreak, Protease, Respiratory, Traditional medicine.