Searching Potential Molecules Against SARS-CoV-2 from Costus arabicus L. Root Smoke: A Docking Study

 The root smoke of Costus arabicus L. (Qust-e Shirin) has been used in Iranian traditional medicine (ITM) for rhinorrhea and catarrh, especially with infectious origin.

 This study aimed to inspect potential anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activities of chemical compositions of this smoke through a docking study.

 Based on our previous study on the chemical compositions of C. arabicus root smoke, the chemical structure of components was revealed by GC-MS. In this study, these structures were generated in HyperChem software, and an energy-minimization procedure was performed for the molecules. For the docking study, the Hex software was used. Docking was performed using the Protein Data Bank (PDB) structure of the COVID-19 RNA-dependent RNA polymerase (RdRp) (PDB ID: 6M71) enzyme which was obtained from PDB bank, water molecules were removed, Coleman charge was added, and non-polar hydrogens were merged. Then, docking was performed.

 The result indicated the energy of each interaction between molecules and enzymes. The lower the energy, the higher the probability of interaction will be. The best molecule was 6H-quindoline which has the best total energy among the molecules. The next molecule was 5-methoxy-alpha methyl tryptamine with -210.82 kcal energy. Their similar structure in indole moiety suggests that this fragment can play a crucial role in attachment to the enzyme and can be kept intact in future designs against COVID-19 inhibitors.

 In conclusion, this study showed that C. arabicus root smoke may be effective in SARS-CoV-2 infection. Further in vitro and in vivo studies on the activity of the smoke and its constituents against COVID-19 would be fruitful.