ABSTRACT
BACKGROUND AND OBJECTIVES: Bacterial DNA topoisomerases are unique in maintaining the DNA topology for cell viability. Mycobacterium tuberculosis (MTB) DNA gyrase, a sole type II topoisomerase has a larger scope as a target for developing novel therapeutics. In this study, an effort was made towards the design and synthesis of benzothiazinone-piperazine hybrid analogues to obtain the possibility of it to lead development through the molecular hybridization technique. METHODS: A five-step scheme was followed to obtain a series of 36 benzothiazinone-piperazine derivatives and to evaluate them for MTB DNA gyrase inhibition, antimycobacterial and cytotoxicity studies. RESULTS: Compound N-(4-chlorophenyl)-4-(6-nitro-4-oxo-4H-benzo[e][1,3]thiazin-2-yl)piperazine-1-carbothioamide (18) showed greater inhibitory potential with an IC50 of 0.51 ± 0.16 µM in the DNA supercoiling assay of MTB with a moderate anti-tubercular activity of 4.41 µM. The compound even passed the safety profile of eukaryotic cell cytotoxicity with a 1.81% inhibition in the RAW 264.7 cell line at 100 µM concentration. CONCLUSIONS: This study describes the discovery of benzothiazinone as gyrase inhibitors with potent MTB MIC and inhibitory profiles of the gyrase enzyme with less cytotoxic effect. Furthermore, it is believed that this class of compounds has the potential to be further developed as an anti-TB drug candidate.
Subject(s)
Antitubercular Agents/pharmacology , Bacterial Proteins/pharmacology , Benzothiadiazines/pharmacology , DNA Gyrase/chemistry , Mycobacterium tuberculosis/drug effects , Piperazines/pharmacology , Topoisomerase II Inhibitors/pharmacology , Antitubercular Agents/chemistry , Bacterial Proteins/chemistry , Benzothiadiazines/chemistry , DNA Gyrase/genetics , DNA Gyrase/metabolism , Drug Design , Humans , Mycobacterium tuberculosis/enzymology , Mycobacterium tuberculosis/genetics , Piperazine , Piperazines/chemistry , Structure-Activity Relationship , Topoisomerase II Inhibitors/chemistry , Tuberculosis/microbiologyABSTRACT
A series of twenty seven substituted 2-(2-oxobenzo[d]oxazol-3(2H)-yl)acetamide derivatives were designed based on our earlier reported Mycobacterium tuberculosis (MTB) enoyl-acyl carrier protein reductase (InhA) lead. Compounds were evaluated for MTB InhA inhibition study, in vitro activity against drug-sensitive and -resistant MTB strains, and cytotoxicity against RAW 264.7 cell line. Among the compounds tested, 2-(6-nitro-2-oxobenzo[d]oxazol-3(2H)-yl)-N-(5-nitrothiazol-2-yl)acetamide (30) was found to be the most promising compound with IC50 of 5.12 ± 0.44 µM against MTB InhA, inhibited drug sensitive MTB with MIC 17.11 µM and was non-cytotoxic at 100 µM. The interaction with protein and enhancement of protein stability in complex with compound 30 was further confirmed biophysically by differential scanning fluorimetry.
Subject(s)
Antitubercular Agents/chemistry , Antitubercular Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Benzoxazoles/chemistry , Benzoxazoles/pharmacology , Mycobacterium tuberculosis/drug effects , Oxidoreductases/antagonists & inhibitors , Tuberculosis/drug therapy , Animals , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Cell Line , Humans , Mice , Microbial Sensitivity Tests , Molecular Docking Simulation , Mycobacterium tuberculosis/enzymology , Oxidoreductases/chemistry , Oxidoreductases/metabolism , Structure-Activity Relationship , Tuberculosis/microbiologyABSTRACT
InhA, the enoyl acyl carrier protein reductase of Mycobacterium tuberculosis (MTB) is an attractive target for developing novel anti-tubercular agents. Twenty eight 2-(4-oxoquinazolin-3(4H)-yl)acetamide derivatives were synthesized and evaluated for their in vitro MTB InhA inhibition. Compounds were further evaluated for their in vitro activity against drug sensitive and resistant MTB strains and cytotoxicity against RAW 264.7 cell line. Compounds were docked at the active site of InhA to understand their binding mode and differential scanning fluorimetry was performed to ascertain their protein interaction and stability.
