In silico screening of potential inhibitor from Andrographis paniculata constituents against three targets of SARS-CoV-2: Main protease, Spike protein, and Nsp15

The current pandemic of COVID-19 is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which has increased the morbidity and mortality rate throughout the world. World Health Organization has declared this COVID-19 outbreak as a health emergency throughout the world. At this time, there are very few drugs against SARS-CoV-2. So, this study aimed to screen 91 Andrographis paniculata against three targets of SARS-CoV-2: main protease, spike protein, and Nsp15 by molecular docking. The calculation result revealed that mostly bioactive compounds from Andrographis paniculata are a good binding affinity with the main   protease than that of Nsp15 and spike protein. The top six compounds and their interactions with the active site were visualized. Among them, 7,8-dimethoxy flavone-5-b-D-glucopyranosyloxy flavone and Stigmasterol compounds from Andrographis paniculata had a superior binding affinity of -11.65 and -11.33 kcal/mol toward the main protease. A detailed understanding of ligand-protein interaction could be helpful in further drug design and development for COVID-19 treatment.