Homology modeling and molecular docking simulation of some novel imidazo[1,2-a]pyridine-3-carboxamide (IPA) series as inhibitors of Mycobacterium tuberculosis

Mustapha Abdullahi,Shola Elijah Adeniji,David Ebuka Arthur,Abdurrashid Haruna

doi:10.1186/s43141-020-00102-1

Mustapha Abdullahi, Shola Elijah Adeniji + Show 2 more

Open Access

https://doi.org/10.1186/s43141-020-00102-1

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Abstract

BackgroundTuberculosis (TB) remains a serious global health challenge that is caused by Mycobacterium tuberculosis and has killed numerous people. This necessitated the urgent need for the hunt and development of more potent drugs against the fast-emerging extensively drug-resistant (XDR) and multiple-drug-resistant (MDR) M. tuberculosis strains. Mycobacterium tuberculosis cytochrome b subunit of the cytochrome bc1 complex (QcrB) was recognized as a potential drug target in M. tuberculosis (25618/H37Rv) for imidazo[1,2-a]pyridine-3-carboxamides whose crystal strucuture is not yet reported in the Protein Data Bank (PDB). The concept of homology modeling as a powerful and useful computational method can be applied, since the M. tuberculosis QcrB protein sequence data are available. ResultsThe homology model of QcrB protein in M. tuberculosis was built from the X-ray structure of QcrB in M. smegmatis as a template using the Swiss-Model online workspace. The modeled protein was assessed, validated, and prepared for the molecular docking simulation of 35 ligands of N-(2-phenoxy)ethyl imidazo[1,2-a] pyridine-3-carboxamide (IPA) to analyze their theoretical binding affinities and modes. The docking results showed that the binding affinity values ranged from − 6.5 to − 10.1 kcal/mol which confirms their resilience potency when compared with 6.0kcal/mol of isoniazid standard drug. However, ligands 2, 7, 22, 26, and 35 scored higher binding affinity values of − 9.60, − 9.80, − 10.10, − 10.00, and − 10.00 kcal/mol, and are respectively considered as the best ligands among others with better binding modes in the active site of the modeled QcrB protein. ConclusionThe information derived in this research revealed some potential hits and paved a route for structure-based drug discovery of new hypothetical imidazo pyridine amide analogs as anti-tubercular drug candidates.

Highlights

Tuberculosis (TB) remains a serious global health challenge that is caused by Mycobacterium tuberculosis and has killed numerous people
The imidazo pyridine amide (IPA) compounds were first reported as potential anti-M. tuberculosis candidates in 2011, and their response activity against M. tuberculosis showed the H37Rv strain to be within the submicromolar range [3, 4]
The homology model of M. tuberculosis QcrB subunit was built with Global Model Quality Estimation (GMQE) score of 0.91 and QMEA N of − 3.86 which suggests good quality and reliability (Fig. 3b)

Summary

Introduction

Tuberculosis (TB) remains a serious global health challenge that is caused by Mycobacterium tuberculosis and has killed numerous people. This necessitated the urgent need for the hunt and development of more potent drugs against the fast-emerging extensively drug-resistant (XDR) and multiple-drug-resistant (MDR) M. tuberculosis strains. Mycobacterium tuberculosis cytochrome b subunit of the cytochrome bc complex (QcrB) was recognized as a potential drug target in M. tuberculosis (25618/H37Rv) for imidazo[1,2-a]pyridine-3-carboxamides whose crystal strucuture is not yet reported in the Protein Data Bank (PDB). The IPA compounds were first reported as potential anti-M. tuberculosis candidates in 2011, and their response activity against M. tuberculosis showed the H37Rv strain to be within the submicromolar range [3, 4]. As novel series of anti-TB inhibitors targeting QcrB, IPAs have recently reaped immense interest; several other novel classes of new IPAs were described to have effective antimycobacterial response [5]

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