Synthesis, Structure-Activity Relationship, and Mechanistic Studies of Aminoquinazolinones Displaying Antimycobacterial Activity

DAIKON: A Data Acquisition, Integration, and Knowledge Capture Web Application for Target-Based Drug Discovery

Primitive data organization practices struggle to deliver at the scale and consistency required to meet multidisciplinary collaborations in drug discovery. For effective data sharing and coordination, a unified platform that can collect and analyze scientific information is essential. We present DAIKON, an open-source framework that integrates targets, screens, hits, and manages projects within a target-based drug discovery portfolio. Its knowledge capture components enable teams to record subsequent molecules as their properties improve, facilitate team collaboration through discussion threads, and include modules that visually illustrate the progress of each target as it advances through the pipeline. It serves as a repository for scientists sourcing data from Mycobrowser, UniProt, PDB. The goal is to globalize several variations of the drug-discovery program without compromising local aspects of specific workflows. DAIKON is modularized by abstracting the database and creating separate layers for entities, business logic, infrastructure, APIs, and frontend, with each tier allowing for extensions. Using Docker, the framework is packaged into two solutions: daikon-server-core and daikon-client. Organizations may deploy the project to on-premises servers or VPC. Active-Directory/SSO is supported for user administration. End users can access the application with a web browser. Currently, DAIKON is implemented in the TB Drug Accelerator program (TBDA).

An Insight on the Prospect of Quinazoline and Quinazolinone Derivatives as Anti-tubercular Agents

Multiple potential drugs have been developed based on the heterocyclic molecules for the treatment of different symptoms. Among the existing heterocyclic molecules, quinazoline and quinazolinone derivatives have been found to exhibit extensive pharmacological and biological characteristics. One significant property of these molecules is their potency as anti-tubercular agents. Thus, both quinazoline and quinazolinone derivatives are modified using different functional groups as substituents for investigating their anti-tubercular activities. We present a summary of the reported anti-tubercular drugs, designed using quinazoline and quinazolinone derivatives, in this review.

Spiropyrimidinetriones: a Class of DNA Gyrase Inhibitors with Activity against Mycobacterium tuberculosis and without Cross-Resistance to Fluoroquinolones

Described here is a series of spiropyrimidinetrione (SPT) compounds with activity against Mycobacterium tuberculosis through inhibition of DNA gyrase. The SPT class operates via a novel mode of inhibition, which involves Mg²⁺-independent stabilization of the DNA cleavage complex with DNA gyrase and is thereby not cross-resistant with other DNA gyrase-inhibiting antibacterials, including fluoroquinolones. Compound 22 from the series was profiled broadly and showed in vitro cidality as well as intracellular activity against M. tuberculosis in macrophages. Evidence for the DNA gyrase mode of action was supported by inhibition of the target in a DNA supercoiling assay and elicitation of an SOS response seen in a recA reporter strain of M. tuberculosis. Pharmacokinetic properties of 22 supported evaluation of efficacy in an acute model of M. tuberculosis infection, where modest reduction in CFU numbers was seen. This work offers promise for deriving a novel drug class of tuberculosis agent without preexisting clinical resistance.

Screening Repurposed Antiviral Small Molecules as Antimycobacterial Compounds by a Lux-Based phoP Promoter-Reporter Platform

The emergence of multidrug-resistant strains and hyper-virulent strains of Mycobacterium tuberculosis are big therapeutic challenges for tuberculosis (TB) control. Repurposing bioactive small-molecule compounds has recently become a new therapeutic approach against TB. This study aimed to identify novel anti-TB agents from a library of small-molecule compounds via a rapid screening system. A total of 320 small-molecule compounds were used to screen for their ability to suppress the expression of a key virulence gene, phop, of the M. tuberculosis complex using luminescence (lux)-based promoter-reporter platforms. The minimum inhibitory and bactericidal concentrations on drug-resistant M. tuberculosis and cytotoxicity to human macrophages were determined. RNA sequencing (RNA-seq) was conducted to determine the drug mechanisms of the selected compounds as novel antibiotics or anti-virulent agents against the M. tuberculosis complex. The results showed that six compounds displayed bactericidal activity against M. bovis BCG, of which Ebselen demonstrated the lowest cytotoxicity to macrophages and was considered as a potential antibiotic for TB. Another ten compounds did not inhibit the in vitro growth of the M. tuberculosis complex and six of them downregulated the expression of phoP/R significantly. Of these, ST-193 and ST-193 (hydrochloride) showed low cytotoxicity and were suggested to be potential anti-virulence agents for M. tuberculosis.

1,3-Diarylpyrazolyl-acylsulfonamides as Potent Anti-tuberculosis Agents Targeting Cell Wall Biosynthesis in Mycobacterium tuberculosis

Phenotypic whole cell high-throughput screening of a ∼150,000 diverse set of compounds against Mycobacterium tuberculosis (Mtb) in cholesterol-containing media identified 1,3-diarylpyrazolyl-acylsulfonamide 1 as a moderately active hit. Structure-activity relationship (SAR) studies demonstrated a clear scope to improve whole cell potency to MIC values of <0.5 μM, and a plausible pharmacophore model was developed to describe the chemical space of active compounds. Compounds are bactericidal in vitro against replicating Mtb and retained activity against multidrug-resistant clinical isolates. Initial biology triage assays indicated cell wall biosynthesis as a plausible mode-of-action for the series. However, no cross-resistance with known cell wall targets such as MmpL3, DprE1, InhA, and EthA was detected, suggesting a potentially novel mode-of-action or inhibition. The in vitro and in vivo drug metabolism and pharmacokinetics profiles of several active compounds from the series were established leading to the identification of a compound for in vivo efficacy proof-of-concept studies.

Tuberculosis: An Update on Pathophysiology, Molecular Mechanisms of Drug Resistance, Newer Anti-TB Drugs, Treatment Regimens and Host- Directed Therapies

Human tuberculosis (TB) is primarily caused by Mycobacterium tuberculosis (Mtb) that inhabits inside and amidst immune cells of the host with adapted physiology to regulate interdependent cellular functions with intact pathogenic potential. The complexity of this disease is attributed to various factors such as the reactivation of latent TB form after prolonged persistence, disease progression specifically in immunocompromised patients, advent of multi- and extensivelydrug resistant (MDR and XDR) Mtb strains, adverse effects of tailor-made regimens, and drug-drug interactions among anti-TB drugs and anti-HIV therapies. Thus, there is a compelling demand for newer anti-TB drugs or regimens to overcome these obstacles. Considerable multifaceted transformations in the current TB methodologies and molecular interventions underpinning hostpathogen interactions and drug resistance mechanisms may assist to overcome the emerging drug resistance. Evidently, recent scientific and clinical advances have revolutionised the diagnosis, prevention, and treatment of all forms of the disease. This review sheds light on the current understanding of the pathogenesis of TB disease, molecular mechanisms of drug-resistance, progress on the development of novel or repurposed anti-TB drugs and regimens, host-directed therapies, with particular emphasis on underlying knowledge gaps and prospective for futuristic TB control programs.

Strategies to Combat Multi-Drug Resistance in Tuberculosis

"Drug resistance is an unavoidable consequence of the use of drugs; however, the emergence of multi-drug resistance can be managed by accurate diagnosis and tailor-made regimens."Antimicrobial resistance (AMR), is one of the most paramount health perils that has emerged in the 21st century. The global increase in drug-resistant strains of various bacterial pathogens prompted the World Health Organization (WHO) to develop a priority list of AMR pathogens. Mycobacterium tuberculosis (Mtb), an acid-fast bacillus that causes tuberculosis (TB), merits being one of the highest priority pathogens on this list since drug-resistant TB (DR-TB) accounts for ∼29% of deaths attributable to AMR. In recent years, funded collaborative efforts of researchers from academia, not-for-profit virtual R&D organizations and industry have resulted in the continuous growth of the TB drug discovery and development pipeline. This has so far led to the accelerated regulatory approval of bedaquiline and delamanid for the treatment of DR-TB. However, despite the availability of drug regimes, the current cure rate for multi-drug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) treatment regimens is 50% and 30%, respectively. It is to be noted that these regimens are administered over a long duration and have a serious side effect profile. Coupled with poor patient adherence, this has led to further acquisition of drug resistance and treatment failure. There is therefore an urgent need to develop new TB drugs with novel mechanism of actions (MoAs) and associated regimens.This Account recapitulates drug resistance in TB, existing challenges in addressing DR-TB, new drugs and regimens in development, and potential ways to treat DR-TB. We highlight our research aimed at identifying novel small molecule leads and associated targets against TB toward contributing to the global TB drug discovery and development pipeline. Our work mainly involves screening of various small molecule chemical libraries in phenotypic whole-cell based assays to identify hits for medicinal chemistry optimization, with attendant deconvolution of the MoA. We discuss the identification of small molecule chemotypes active against Mtb and subsequent structure-activity relationships (SAR) and MoA deconvolution studies. This is followed by a discussion on a chemical series identified by whole-cell cross-screening against Mtb, for which MoA deconvolution studies revealed a pathway that explained the lack of in vivo efficacy in a mouse model of TB and reiterated the importance of selecting an appropriate growth medium during phenotypic screening. We also discuss our efforts on drug repositioning toward addressing DR-TB. In the concluding section, we preview some promising future directions and the challenges inherent in advancing the drug pipeline to address DR-TB.

Current advances in the clinical development of anti-tubercular agents

Tuberculosis (TB) is a communicable airborne infectious disease caused by the Mycobacterium tuberculosis (MTB) that primarily affects the lungs, and can disseminate to other parts of the body. MTB is one of the most dangerous pathogens, killing about 1.4 million people annually worldwide. Although the standard treatment of TB is comprised of four anti-TB drugs, the emergence of multidrug-resistant (MDR) and extensive drug-resistant (XDR) strains in the recent past and associated side effects have affected the tailor-made regimens. Notably, existing therapies approved by the World Health Organisation (WHO) can only treat less than 50% of drug-resistant TB. Therefore, an expeditious pace in the TB research is highly needed in search of effective, affordable, least toxic novel drugs with shorter regimens to reach the goals viz. 2020 milestones End TB strategy set by the WHO. Currently, twenty-three drug-like molecules are under investigation in different stages of clinical trials. These newer agents are expected to be effective against the resistant strains. This article summarizes the properties, merits, demerits, and the probability of their success as novel potential therapeutic agents.