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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 the hit compound of a promising anti-TB compound class. Herein we report systematic variations around the central pyrrole core of BM635 and we describe the design, synthesis, biological evaluation, pharmacokinetic analysis, as well as in vivo TB mouse efficacy studies of novel BM635 analogues that show improved physicochemical properties. This hit-to-lead campaign led to the identification of a new analogue, 4-((1-isopropyl-5-(4-isopropylphenyl)-2-methyl-1H-pyrrol-3-yl)methyl)morpholine (17), that shows excellent activity (MIC = 0.15 μM; SI = 133) against drug-sensitive Mycobacterium tuberculosis strains, as well as efficacy in a murine model of TB infection., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

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., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

According to the latest World Health Organization (WHO) report, an estimated 10.6 million people were diagnosed with tuberculosis (TB) in 2022, and 1.30 million died. A major concern is the emergence of multi-drug-resistant (MDR) and extensively drug-resistant (XDR) strains, fueled by the length of anti-TB treatment and HIV comorbidity. Innovative anti-TB agents acting with new modes of action are the only solution to counteract the spread of resistant infections. To escape starvation and survive inside macrophages, Mtb has evolved to become independent of the host by synthesizing its own amino acids. Therefore, targeting amino acid biosynthesis could subvert the ability of the mycobacterium to evade the host immune system, providing innovative avenues for drug discovery. The aim of this review is to give an overview of the most recent progress in the discovery of amino acid biosynthesis inhibitors. Among the hits discovered over the past five years, tryptophan (Trp) inhibitors stand out as the most advanced and have significantly contributed to demonstrating the feasibility of this approach for future TB drug discovery. Future efforts should be directed at prioritizing the chemical optimization of these hits to enrich the TB drug pipeline with high-quality leads. [ABSTRACT FROM AUTHOR]

Tuberculosis remains one of the world's deadliest infectious diseases, accounting for nearly 1.3 million deaths every year. Tuberculosis treatment is challenging because of the toxicity, decreased bioavailability at the target site of the conventional drugs and, most importantly, low adherence of patients; this leads to drug resistance. Here, we describe the development of suitable nanocarriers with specific physicochemical properties to efficiently deliver two potent antimycobacterial compounds. We prepared nanoemulsions and niosomes formulations and loaded them with two different MmpL3 inhibitors previously identified (NEs + BM635 and NIs + BM859). NEs + BM635 and NIs + BM859 were deeply characterized for their physicochemical properties and anti-mycobacterial activity. NEs + BM635 and NIs + BM859 showed good hydrodynamic diameter, ζ-Potential, PDI, drug-entrapment efficiency, polarity, and microviscosity and stability. Even though both formulations proved to perform well, only NIs + BM859 showed potent antimycobacterial activity against M. tuberculosis (MIC = 0.6 µM) compared to that of the free compound. This is most probably caused by the fact that BM635, being highly hydrophobic, encounters maximum hindrance in diffusion, whereas BM859, characterized by high solubility in aqueous medium (152 µM), diffuses more easily. The niosomal formulation described in this work may be a useful therapeutic tool for tuberculosis treatment, and further studies will follow to characterize the in vivo behavior of the formulation. [ABSTRACT FROM AUTHOR]

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]