Synthesis and Antitubercular activity of New Thiazolidinones with Pyrazinyl and Thiazolyl Scaffolds

Ynamide-Mediated Thioamide and Primary Thioamide Syntheses

Environmentally friendly ynamide-mediated thioamidation of monothiocarboxylic acids with amines or ammonium hydroxide for the syntheses of thioamides and primary thioamides is described. Simple and mild reaction conditions enable the reaction to tolerate a wide variety of functional groups such as hydroxyl group, ester, tertiary amine, ketone, and amide moieties. Readily available NaSH served as the sulfur source, avoiding the use of toxic, expensive, and malodorous organic sulfur reagents and making this strategy environmentally friendly and practical. Importantly, the stereochemical integrity of α-chiral monothiocarboxylic acids was maintained during the activation step and subsequent aminolysis process, thus offering a racemization-free strategy for peptide C-terminal modification. Furthermore, a number of thioamide-modified drugs were prepared in good yields by using this protocol and the synthesized primary thioamides were transformed into backbone thiazolyl modified peptides.

Synthesis of new 2-(thiazol-4-yl)thiazolidin-4-one derivatives as potential anti-mycobacterial agents

To search for potent antimycobacterial lead compounds, a new series of 3-substituted phenyl-2-(2-(substituted phenyl)thiazol-4-yl) thiazolidin-4-one (5a-t) derivatives have been synthesized by the condensation of 2-substituted phenyl thiazole-4-carbaldehyde with aromatic amine followed by cyclocondensation with thioglycolic acid. The structure of the newly synthesized 2-(thiazol-4-yl)thiazolidin-4-one derivatives were characterized by the spectroscopic analysis. The synthesized compounds were screened for antimycobacterial activity against Mycobacterium tuberculosis H37Ra (MTB) (ATCC 25177) and Mycobacterium bovis BCG (BCG, ATCC 35743). Most of the 2-(thiazol-4-yl)thiazolidin-4-one derivatives showed good to excellent antimycobacterial activity against both the Mtb strains. Nine derivatives 5c, 5g, 5j, 5m, 5n, 5o, 5p, 5s, and 5t showed excellent activity against M. bovis BCG with MIC 4.43 to 24.04 μM were further evaluated for the cytotoxicity activity against HeLa A549, and HCT-116 cell lines and showed no significant cytotoxic activity at the maximum concentration evaluated. The potential antimycobacterial activities enforced that the thiazolyl-thiazolidin-4-one derivatives could lead to compounds that could treat tuberculosis.

Contribution of N-heterocycles towards anti-tubercular drug discovery (2014-2019); predicted and reengineered molecular frameworks

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, responsible for high death frequency every year all over the world. In this regard, efficient drug-design and discovery towards the prevention of M.tb H₃₇ R_v is of prime concern. Prevention of the infection may include vaccination, and the treatment comprises anti-TB drug regimen. However, the vaccine decreases the risk of tuberculosis infection only to some extent, while drug-resistance limits the efficacy of the existing anti-TB agents. Much improvement has to be achieved to overcome pitfalls such as side effects, high-toxicity, low bioavailability, pharmacokinetics and pharmacodynamics, and hence forth in clinical therapeutics. Amongst heterocyclic compounds, N-heterocycles played a pivotal role in drug-design and discovery. A wide range of microbial diseases are being treated by the N-heterocyclic drugs. The present review comprises description of anti-TB effects of the N-heterocycles such as indoles, triazoles, thiazoles, and pyrazoles. The potent anti-TB activity exerted by the derivatives of these heterocycles is evaluated critically alongside emphasizing structure-activity relationship. Besides, docking studies supporting anti-TB activity is supplemented. Alongside this, based on the potent heterocyclic molecules, the molecular frameworks are designed that would bring about enhanced M. tb H₃₇ R_v inhibitory potencies.

Antitubercular properties of thiazolidin-4-ones - A review

Thiazolidin-4-one scaffold has great potential for medicinal chemistry and is of interest to scientists in view of wide spectrum of biological activity. This scaffold is often used for designing of small molecules with various biological activity including antituberculosis activity. The presented review is an attempt to gather, analyze and systemize data about antitubercular properties of thiazolidine-4-ones from two last decades. Some of them have promising antitubercular activity which is significantly higher than that of the reference drugs. Among them compounds 82c, 82d and 84 that were active against M. tuberculosis H37Rv strain with MICs in the range of 0.05-0.2 μg/mL and compound 108 exhibited activity with MIC = 0.36 μM. Compounds 115a-115c and 116a-116c were very effective against M. tuberculosis H37Ra with MIC values in the range of 0.031-0.125 μg/mL. Acidomycin was showed activity against seven MDR M. tuberculosis strains with MICs in the range of 0.6-0.62 μM and against two XDR M. tuberculosis strains with MICs 0.096 and 1.2 μM. The structure-activity relationship (SAR) of some groups of compounds, as well as some potential molecular targets were also discussed.