Design, Synthesis and Evaluation of Antitubercular Activity of Novel 1,2,4-Triazoles Against MDR Strain of Mycobacterium tuberculosis

Advances in the application of 1,2,4-triazole-containing hybrids as anti-tuberculosis agents

Tuberculosis is a deadly communicable disease caused by the bacillus Mycobacterium tuberculosis (MTB), and pulmonary tuberculosis accounts for over 80% of the total cases. The 1,2,4-triazole is a privileged structure in the discovery of new drugs, and its derivatives act on various targets in MTB. In particular, 1,2,4-triazole hybrids can not only exert dual or multiple antitubercular mechanisms of action but also have the potential to enhance efficacy and reduce side effects. The present work aims to summarize the current status of 1,2,4-triazole hybrids as potential antitubercular agents, covering articles published between 2010 and 2020, to aid the further rational design of novel potential drug candidates endowed with higher efficacy, better compliance and fewer side effects.

A Comparative Study of 1D Descriptors Supported CoMFA and CoMSIA QSAR Models to Gain Novel Insights into 1,2,4-Triazoles Acting As Antitubercular Agents

BACKGROUND

Tuberculosis is one of the leading causes of deaths due to infectious disease worldwide. There is an urgent need for developing new drugs due to the rising incidents of drug resistance. Previously, triazole molecules showing antitubercular activity, were reported. Various computational tools pave the way for a rational approach to understanding the structural importance of these compounds in inhibiting the growth of Mycobacterium Tuberculosis.

OBJECTIVE

The aim of this study is to develop and compare two different QSAR models based on a set of previously reported triazole molecules and use the best one for gaining structural insights into those molecules.

METHODS

In this current study, two separate models were made with CoMFA and CoMSIA descriptors based on a dataset of triazole molecules showing antitubercular activity. Several one dimensional (1D) descriptors were added to each of the models and the validation results and contour data generated from them were compared. The best model was analysed to give a detailed understanding of the triazole molecules and their role in the antitubercular activity.

RESULTS

The r², q², predicted r² and SEP (Standard error of prediction) for the CoMFA model were 0.866, 0.573, 0.119 and 0.736 respectively and for the CoMSIA model, the r², q², predicted r² and SEP were calculated to be 0.998, 0.634, 0.013 and 0.869 respectively. Although both the QSAR models produced acceptable internal and external validation scores, but the CoMSIA results were significantly better. The CoMSIA contours also provided a better match than CoMFA with most of the features of the active compound 30b. Hence, the CoMSIA model was chosen and its contours were explored for gaining structural insights into the triazole molecules.

CONCLUSION

The CoMSIA contours helped us understand the role of several atoms and groups of the triazole molecules in their biological activity. The possibilities for substitution in the triazole compounds that would enhance the activity were also analyzed. Thus, this study paves the way for designing new antitubercular drugs in future.

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.

Synthesis of 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides and their tautomerism

Two complementary pathways for the preparation of N-substituted 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides (5) were proposed and successfully realized in the synthesis of 20 representative examples. These methods use the same types of starting materials viz. succinic anhydride, aminoguanidine hydrochloride, and a variety of amines. The choice of the pathway and sequence of the introduction of reagents to the reaction depended on the amine nucleophilicity. The first pathway started with the preparation of N-guanidinosuccinimide, which then reacted with amines under microwave irradiation to afford 5. The desired products were successfully obtained in the reaction with aliphatic amines (primary and secondary) via a nucleophilic opening of the succinimide ring and the subsequent recyclization of the 1,2,4-triazole ring. This approach however failed when less nucleophilic aromatic amines were used. Therefore, an alternative pathway, with the initial preparation of N-arylsuccinimides and their subsequent reaction with aminoguanidine hydrochloride under microwave irradiation, was applied. The annular prototropic tautomerism in the prepared 1,2,4-triazoles 5 was studied using NMR spectroscopy and X-ray crystallography.

Two complementary pathways for the preparation of N-substituted 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides were proposed and successfully realized in the synthesis of 20 representative examples.