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The biosynthetic pathways of amino acids are attractive targets for drug development against pathogens with an intracellular behavior like M. tuberculosis (Mtb). Indeed, while in the macrophages Mtb has restricted access to amino acids such as tryptophan (Trp). Auxotrophic Mtb strains, with mutations in the Trp biosynthetic pathway, showed reduced intracellular survival in cultured human and murine macrophages and failed to cause the disease in immunocompetent and immunocompromised mice. Herein we present recent efforts in the discovery of Trp biosynthesis inhibitors., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

BM635 is a small molecule endowed with outstanding anti-mycobacterial activity (minimum inhibitory concentration of 0.12 μM against M. tuberculosis H37Rv) identified during a hit-to-lead campaign. Its poor aqueous solubility together with its high lipophilicity led to low exposure in vivo. Indeed, the half-life in vivo of BM635 was 1 h, allowing a reasonable maximum concentration (C max = 1.62 μM) and a moderate bioavailability (46%). The present study aimed to develop salt forms of BM635 with pharmaceutically accepted hydrochloric, methanesulphonic, phosphoric, tartaric, and citric acids to overcome these drawbacks. BM635 salts (BM635-HCl, BM635-Mes, BM635-PA, BM635-TA and BM635-CA) were evaluated for physicochemical as well as biopharmaceutical attributes. [ABSTRACT FROM AUTHOR]

A major constraint in reducing tuberculosis epidemic is the emergence of strains resistant to one or more of clinically approved antibiotics, which emphasizes the need of novel drugs with novel targets. Genetic knockout strains of Mycobacterium tuberculosis (Mtb) have established that tryptophan (Trp) biosynthesis is essential for the bacterium to survive in vivo and cause disease in animal models. An anthranilate-like compound, 6-FABA , was previously shown to synergize with the host immune response to Mtb infection in vivo. Herein, we present a class of anthranilate-like compounds endowed with good antimycobacterial activity and low cytotoxicity. We show how replacing the carboxylic moiety with a hydrazide led to a significant improvement in both activity and cytotoxicity relative to the parent compound 6-FABA. Several new benzohydrazides (compounds 20 – 31 , 33 , 34 , 36 , 38 and 39) showed good activities against Mtb (0.625 ≤ MIC≤6.25 μM) and demonstrated no detectable cytotoxicity against Vero cell assay (CC 50 ≥ 1360 μM). The target preliminary studies confirmed the hypothesis that this new class of compounds inhibits Trp biosynthesis. Taken together, these findings indicate that fluorophenylbenzohydrazides represent good candidates to be assessed for drug discovery. [Display omitted] • Anthranilate-like compounds showed good antimycobacterial activity. • Hydrazides significantly improved the activity relatively to the parent compound. • 6-Fluorophenylbenzohydrazides possibly inhibit Trp biosynthesis. [ABSTRACT FROM AUTHOR]

Tuberculosis remains the world's top infectious killer: it caused a total of 1.5 million deaths and 10 million people fell ill with TB in 2018. Thanks to TB diagnosis and treatment, mortality has been falling in recent years, with an estimated 58 million saved lives between 2000 and 2018. However, the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains is a major concern that might reverse this progress. Therefore, the development of new drugs acting upon novel mechanisms of action is a high priority in the global health agenda. With the approval of bedaquiline, which targets mycobacterial energy production, and delamanid, which targets cell wall synthesis and energy production, the energy-metabolism in Mtb has received much attention in the last decade as a potential target to investigate and develop new antimycobacterial drugs. In this review, we describe potent anti-mycobacterial agents targeting the energy-metabolism at different steps with a special focus on structure-activity relationship (SAR) studies of the most advanced compound classes. [ABSTRACT FROM AUTHOR]

Despite enormous efforts have been made in the hunt for new drugs, tuberculosis (TB) still remains the first bacterial cause of mortality worldwide, causing an estimated 8.6 million new cases and 1.3 million deaths in 2012. Multi-drug resistant-TB strains no longer respond to first-line drugs and are inexorably spreading with an estimated 650 000 cases as well as extensively-drug resistant-TB strains, which are resistant to any fluoroquinolone and at least one of the second-line drugs, with 60 000 cases. Thus the discovery and development of new medicines is a major keystone for tuberculosis treatment and control. After decades of dormancy in the field of TB drug development, recent efforts from various groups have generated a promising TB drug pipeline. Several new therapeutic agents are concurrently studied in clinical trials together with much activity in the hittolead and lead optimization stages. In this article we will review the recent advances in TB drug discovery with a special focus on structure activity relationship studies of the most advanced compound classes. [ABSTRACT FROM AUTHOR]