Investigation of the Anti-TB Potential of Selected Phytochemicals of Nigella Sativa using Molecular Docking Approach

Background: Tuberculosis (TB) is one of the foremost causes of human mortality across the world. In general, it is a curable disease and several drugs are available in market for its treatment, however, because of the drug resistance to the currently available anti-TB drugs, the development and/or discovery of new drugs with better efficacy against TB cannot be overlooked. In the present study, we performed virtual screening of the major phytochemicals of the plant Nigella sativa for investigating their potential to inhibit some novel drug targets of Mycobacterium tuberculosis, which included- pantothenate kinase, type 1 (MtPanK), β-ketoacyl ACP synthase I (MtKasA), and decaprenylphosphoryl-β-D-ribose 2′-epimerase 1 (MtDprE1).

Methods: The screening of the phytochemicals was investigated through a molecular docking approach using Auto dock vina and the molecular interactions in the protein-ligand complexes were visualized and analysed through PyMol and BioVia Discovery Studio Visualizer.

Results: Our in silico observations reveal that, out of the nine selected phytochemicals screened, five compounds, namely α-hederin, dithymoquinone, nigellidine, thymoquinone and thymol binded to one or more of the selected target enzymes with significant docking scores. α-hederin binded to MtDprE1 and MtKasA with a docking score of −8.5kcal/mol and −7.9kcal/mol, respectively, dithymoquinone binded to MtKasA, MtDprE1 and MtPanK with a docking score of −6.5kcal/mol, −8.2kcal/mol and −9.2kcal/mol, respectively and nigellidine binded to MtDprE1 and MtPanK with a docking score of −8.1kcal/mol and −8.2kcal/mol, respectively. Further, thymol as well as thymoquinone were observed to bind MtKasA with a docking score of −6.6kcal/mol.

Conclusions: The results of our study indicate that the five phytochemicals of N. sativa, including α-hederin, dithymoquinone, nigellidine, thymoquinone and thymol, are worth studying further for their anti-TB activity, however, additional biological studies are warranted to validate these findings.