Current landscape of natural products against coronaviruses: perspectives in COVID-19 treatment and antiviral mechanism

BACKGROUND: SARS-CoV-2 is a coronavirus, of which infection causing COVID-19 was first reported in Wuhan, China at the end of 2019, and the outbreak became pandemic in February of 2020 Till now there is no effective drug or vaccine against this virus that can make complete cure;however, a number of drugs are in trials OBJECTIVES: In this review, we have focused on an alternative therapeutic approach using natural products utilizing host anti-viral responses for resolving COVID-19 pathogenesis METHODS: We have searched databases like PubMed, Scopus, Web of Science and Google Scholar for articles related to natural products and viral diseases, with a specific focus on coronaviruses, as well as other RNA viruses and recent updates on COVID-19 pandemic, and collected articles and reviewed comprehensively RESULTS: Scientific studies clarified the viral pathogenesis that involved viral entrance into host cells, and antiviral response inside the cells, which can be effectively targeted by numerous natural compounds from different sources Many of these compounds can potentially target viral genomic material or protein machinery Natural products which were found effective against other coronaviruses, especially SARS-CoV or MERS-CoV (which emerged in 2002 and 2012, respectively) might be effective against SARS-CoV-2 due to their structural similarities;however, it needs time to establish the clinical success of these drugs CONCLUSION: COVID-19 pandemic is a global emergency problem and urgent drug development is necessary Natural products can be the biggest source of drugs, as they have been found effective in other coronaviruses previously;however, it needs time to establish these drugs for clinical application