Antiviral activity of Matricaria chamomilla in the treatment of COVID-19: Molecular Docking study

Introduction: SARS-CoV-2 infection is a lethal disease caused by a Novel strain of coronaviruses. Although vaccinations of healthy people and meticulous treatment of infected people are the main global health concerns, some plant species have therapeutic effects against viral infections. Matricaria chamomilla is one of the most famous medicinal plants used to manage flu or flu-like symptoms due to its antiviral bioactivity. M. chamomilla belongs to a large group of medicinal herbs used by Persian scholars such as Avicenna and Rhazes to treat respiratory diseases. It has more than 120 chemical constituents, including terpenoids, flavonoids, and some components with potential medicinal activity. In this study, the inhibitory effect of 2 major flavonoid components of M. chamomilla, apigenin and luteolin, was studies for the main protease protein of SARS-CoV-2. Methods: Molecular docking studies were performed using an in-house batch script (DOCKFACE) of Auto Dock 4.2. The 3D structures of the selected flavonoids were retrieved from PubChem, and each ligand was optimized with MM+ then AM1 minimization method using HyperChem 8. The 3D crystal structure of the main protease protein of SARS-CoV-2 (PDB ID: 6LU7) was obtained from the Protein Data Bank (http://www.rcsb.org./pdb). Results: Apigenin and luteolin exhibited good docking scores against 6LU7 receptor, -7.86 and -7.24, respectively, with a combination of hydrogen bonding, van der Waals, and other hydrophobic interactions in the docked complexes. Besides, the estimated inhibition constants, Ki, showed that luteolin exhibited a better inhibitory effect than apigenin. Conclusions: Based on these results, the authors proposed that M. chamomilla can be considered as a valuable resource recommended for preventing SARS-CoV-2 invasion into the human body. Keywords: COVID-19, M. chamomilla, Persian medicine, Molecular Docking, Herbal medicine