A computational study on active constituents of Habb-ul-aas and Tabasheer as inhibitors of SARS-CoV-2 main protease

A respiratory pandemic known as coronavirus disease-19 (COVID-19) has created havoc since it emerged from Wuhan, China. COVID-19 is caused by a newly emerged SARS coronavirus (SARS-CoV) with increased pathogenicity named severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Due to the lack of understanding of the mechanism of pathogenesis, an effective therapeutic option is unavailable. Epidemics described in Unani ancient literature include nazla-e-wabai and humma-e-wabai, and most of the symptoms of COVID-19 resemble nazla-e-wabai. Hence, in light of Unani literature, the treatment of COVID-19 can be managed with the composites prescribed in Unani medicine for nazla-e-wabai. In this study, a structure-based drug design approach was carried out to check the effectiveness of the pharmacologically active constituents of the Unani composites prescribed to treat nazla-e-wabai against SARS-CoV-2. We performed molecular docking of the active constituents of these composites against the main protease (M^pro), a potential drug target in SARS-CoV-2. Using detailed molecular docking analysis, Habb-ul-aas and Tabasheer were identified as potential inhibitors of SARS-CoV-2 M^pro. The active constituents of both these composites bind to the substrate-binding pocket of SARS-CoV-2 M^pro, forming interactions with key residues of the binding pocket. Molecular dynamics (MD) simulation suggested the binding of active constituents of Habb-ul-aas with SARS-CoV-2 M^pro with a strong affinity as compared to the constituents of Tabasheer. Thus, this study sheds light on the use of these Unani composites in COVID-19 therapeutics. Communicated by Ramaswamy H. Sarma.