Structure-based in silico and in vitro Analysis Reveals Asiatic Acid as Novel Potential Inhibitor of Mycobacterium...

The present study aimed to search for novel potent inhibitor(s) against the recently discovered maltosyltransferase (GlgE) target of M.tb.

GlgE belongs to an α-amylase family and catalyzes the elongation of cytosolic branched α-glucan. Inactivation of M.tb. GlgE results in DNA damage and rapid death of M.tb. due to the accumulation of a toxic altosyl donor, maltose-1-phosphate (M1P), suggesting that GlgE is an intriguing target for inhibitor design.

1000 natural compounds were compiled from public databases and literature through virtual screening, of which 25 compounds were found to satisfy all drug-likeness properties and ADME/ toxicity criteria, followed by molecular docking with GlgE. Compound(s) showing the lowest binding energy was further subjected to molecular dynamics simulation (MDS) and in vitro analysis.

Molecular docking analysis allowed the selection of 5 compounds withsignificant binding affinity to GlgE targets. Amongst these compounds, asiatic acid exhibited the lowest binding energy (-12.61 kcal/mol). The results of 20-ns MDS showed that asiatic acid formed a stable complex with GlgE. Additionally, asiatic acid exhibited in vitro anti-mycobacterial activity against M.tb. H37Ra, M. bovis BCG, and M. smegmatis strains.

The study reveals asiatic acid as a promising anti-mycobacterial agent that might emerge as a novel natural anti-TB lead molecule in the future.