Pharmacophore based approach to screen and evaluate novel Mycobacterium cell division inhibitors targeting FtsZ – A modelling and experimental study

Abstract

Tuberculosis, caused by Mycobacterium tuberculosis has been one of the primal afflictions to human, and owing to the current scenario of drug resistance, newer drugs, and alternate targets are required to mitigate the disease. FtsZ is a GTP hydrolyzing protein, conserved in prokaryotes that plays a central role in Z-ring formation during cell division cytokinesis stage. This study employs the use of pharmacophore models derived from two different datasets based on Mtb-FtsZ GTPase inhibition and whole cell antibacterial activity, to virtually screen and shortlist novel compounds from In-house small molecule library as Mtb-FtsZ inhibitors and evaluate their in-vitro and ex-vivo activity. The results revealed Piperine (IC50 = 21.2 ± 0.7 μM), 4-Bromo di-methoxy coumarin (IC50 = 13.0 ± 1.6 μM) and Di-ethyl amino methyl coumarin (IC50 = 19.4 ± 1.1) as potent Mtb-FtsZ GTPase inhibitors which showed considerable antibacterial activity (84.0 ± 2.6 μM, 56.0 ± 4.3 μM and 108 ± 7.1 μM respectively) against M. smegmatis. They appear to be bacteriostatic, as well as treatment with these compounds led to a 3× increase in cell length of M. smegmatis. Further these molecules also altered the FtsZ gene expression by 3-fold when compared to untreated. In addition compound Aloin, an Aloe exudate showed potent Mtb-FtsZ inhibition (IC50 = 16.7 ± 0.4 μM) but exhibited poor anti-mycobacterial activity (>500 μM).