Title:Design, Docking, Synthesis, and In vitro Evaluation of Potent Anti-tubercular Agents Targeting DNA Gyrase
Volume: 21
Issue: 11
Author(s): Manjiri D. Bhosale, Asha B. Thomas*, Kiran B. Lokhande, Kakumani V. Swamy, Soumya Basu and Sohan S. Chitlange
Affiliation:
- Department of Pharmaceutical Chemistry, Dr. D. Y. Patil Institute of Pharmaceutical Science and Research, affiliated
to SPPU, Pimpri, Pune, Maharashtra, 411 018, India
Keywords:
Antitubercular agents, DNA gyrase, DNA supercoiling assay, n-heterocyclic compounds, N-methyl piperazine, Mycobacterium tuberculosis.
Abstract:
Background: Tuberculosis caused by Mycobacterium tuberculosis has been reported to infect
about two-third of the global population and to continuously develop multidrug resistance. DNA gyrase, a
type II topoisomerase, is a promising target of the quinolone class of drugs in the treatment of tuberculosis.
Objective: The present study is focused on the design and synthesis of newer nitrogen heterocyclics containing
indole, n-methyl piperazine, piperidine, and pyrrolidine ring structures.
Methods: Initially designed compounds were evaluated for their affinity to the DNA gyrase target. The
molecular docking performed using FlexX indicated compounds IIb5 (1-(R)-(4-hydroxyphenyl)(4-
methylpiperazin-1-yl)methyl)-3-((S)-(4-hydroxyphenyl)(4-methylpiperazin-1-yl)methyl)urea and IIc5
((1-(R)-(4-hydroxyphenyl)(4-methylpiperazin-1-yl)methyl)-3-((S)-(4-hydroxyphenyl)(4-methylpiperazin-
1-yl)methyl) thiourea to exhibit promising binding affinity (dock score of -15.01 and -13.77) respectively
when compared to the reference MFX moxifloxacin (dock score -4.40) with the target 5BS8 (DNA gyrase).
Further, the best 10 compounds were synthesized by one-pot synthesis employing the reaction of
indole/N-methyl piperazine/piperidine/pyrrolidine with N-substituted benzaldehydes in the presence of
acetamide/urea/thiourea to afford the compounds in 54.60% to 85.47% yield. The synthesized compounds
were suitably characterized using chromatographic and spectroscopic tools.
Results: In the microplate Alamar Blue assay (MABA), compounds IIb1, IIIc2, IIIb1, and IIb5 exhibited
good minimum inhibitory concentrations of 1.6 μg/mL, 3.12 μg/mL, and 12.5 μg/mL, respectively, when
compared to the standard rifampicin with 0.8 μg/mL inhibitory concentration. The MTB gyrase supercoiling
assay performed using Mycobacterium tuberculosis gyrase supercoiling assay kit demonstrated compound
IIb5 at a concentration of 300 μg/mL to show gyrase inhibition in comparison to MFX at 60
μg/mL. In the MTT assay performed using the human breast cancer cell line MCF-7, compounds IIc2,
IIb5, and IIb1 showed IC50 values of 2.57 μM, 12.54 μM, and 12.75 μM, respectively, compared to doxorubicin
(1.10 μM) at 7-48 hrs and 72 hrs of the study.
Conclusion: Based on these observations, N-methyl piperazine class of compounds can serve as a
lead/pharmacophore for the rational design of potent molecules against MTB gyrase to combat the growing
issue of MDR-TB.
