Molecular docking of quinine, chloroquine and hydroxychloroquine to angiotensin converting enzyme 2 (ACE2) receptor for discovering new potential COVID-19 antidote

Researches on drugs to be used for COVID-19 therapy are still challenging. SARS-CoV-2 uses the angiotensin-converting enzyme (ACE2) receptor to enter the human body. The S (spike) protein structure of SARS-CoV-2 interacts with the active site of ACE2 receptor, defined as the peptidase domain, which consists of Gln24, Asp30, His34, Tyr41, Gln42, Met82, Lys353, Arg357. This work studied the interaction of three quinoline-based antimalarial drugs with the peptidase domain of ACE2 receptor. The X-ray crystal structure of human ACE2 receptor was downloaded from Protein Data Bank. The ligands were built using MarvinSketch and were geometry optimized using MMFF94 in LigandScout. The energy-minimized ligands were docked to the peptidase domain of ACE2 receptor. Results showed that chloroquine, hydroxychloroquine, and quinine can interact with amino acid residues in the peptidase domain of the ACE2 receptor. Of the three compounds, quinine shows the strongest affinity to the ACE2 receptor (-4.89 kcal/mol) followed by hydroxychloroquine (-3.87 kcal/mol), and chloroquine (-3.17 kcal/mol), respectively. In conclusion, quinine, chloroquine, and hydroxychloroquine could block the infection of the SARS-CoV-2 virus by interacting with residue Lys353 in the peptidase domain of ACE2 receptor, thus potential to be used as COVID-19 antidote. This study will add more insights to the mechanism of quinoline-based antimalarial drugs in inhibiting the infection of the SARS-CoV-2 virus.