Identification of SARS-CoV-2 3CL protease and PL protease inhibitory effects among natural compounds: Structure-based virtual screening based on molecular docking and MM-GBSA studies

SARS-CoV-2 is a new coronavirus spread from Wuhan, China, in December 2019. The virus spread rapidly around the world and in March 2020, made the World Health Organization declare it as a pandemic. SARS-CoV-2 cause a pneumonia-like illness called COVID-19 that due to a large number of infected people and deaths, it hadbecome an international health crisis. SARS-CoV-2 has two peptides called 3-chymotrypsin-like protease and papain-like protease that their principal function is to cut the raw viral polyproteins and convert them to the functional proteins which are essential for pathogenesis and proliferation of the virus. Natural compounds have always been considered for the treatment of diseases and also as lead compounds for drug discovery.