8 research outputs found
Label-free affinity screening, design and synthesis of inhibitors targeting the <i>Mycobacterium tuberculosis</i> L-alanine dehydrogenase
The ability of Mycobacterium tuberculosis (Mtb) to persist in its host may enable an evolutionary advantage for drug resistant variants to emerge. A potential strategy to prevent persistence and gain drug efficacy is to directly target the activity of enzymes that are crucial for persistence. We present a method for expedited discovery and structure-based design of lead compounds by targeting the hypoxia-associated enzyme L-alanine dehydrogenase (AlaDH). Biochemical and structural analyses of AlaDH confirmed binding of nucleoside derivatives and showed a site adjacent to the nucleoside binding pocket that can confer specificity to putative inhibitors. Using a combination of dye-ligand affinity chromatography, enzyme kinetics and protein crystallographic studies, we show the development and validation of drug prototypes. Crystal structures of AlaDH-inhibitor complexes with variations at the N6 position of the adenyl-moiety of the inhibitor provide insight into the molecular basis for the specificity of these compounds. We describe a drug-designing pipeline that aims to block Mtb to proliferate upon re-oxygenation by specifically blocking NAD accessibility to AlaDH. The collective approach to drug discovery was further evaluated through in silico analyses providing additional insight into an efficient drug development strategy that can be further assessed with the incorporation of in vivo studies
New tuberculosis drug targets, their inhibitors, and potential therapeutic impact
The current tuberculosis (TB) predicament poses numerous challenges and therefore every incremental scientific work and all positive socio-political engagements, are steps taken in the right direction to eradicate TB. Progression of the late stage TB-drug pipeline into the clinics is an immediate deliverable of this global effort. At the same time, fueling basic research and pursuing early discovery work must be sustained to maintain a healthy TB-drug pipeline. This review encompasses a broad analysis of chemotherapeutic strategies that target the DNA replication, protein synthesis, cell wall biosynthesis, energy metabolism and proteolysis of Mycobacterium tuberculosis (Mtb). It includes a status check of the current TB-drug pipeline with a focus on the associated biology, emerging targets, and their promising chemical inhibitors. Potential synergies and/or gaps within or across different chemotherapeutic strategies are systematically reviewed as well
Anti-Microbial Activity of Aliphatic Alcohols from Chinese Black Cardamom (<i>Amomum tsao</i>-<i>ko</i>) against <i>Mycobacterium tuberculosis</i> H37Rv
The fruits of Amomun tsao-ko (Chinese black cardamom; Zingiberaceae) contain an abundance of essential oils, which have previously demonstrated significant antimicrobial activity. In our preliminary search for natural anti-tuberculosis agents, an acetone extract of A. tsao-ko (AAE) exhibited strong antibacterial activity against Mycobacterium tuberculosis H37Rv. Therefore, the aim of this study was to find the principal compounds in an AAE against M. tuberculosis. Nine aliphatic compounds (1–9) including a new compound (1, tsaokol B) and a new natural unsaturated aliphatic diester (6), together with three acyclic terpenoids (10–12), were isolated from an AAE by repetitive chromatography. The structures of the isolates were determined by spectroscopic data analysis. All isolates were evaluated for activity against M. tuberculosis H37Rv. Isolated compounds 1–6, and 11 had MICs ranging from 0.6–89 µg/mL. In contrast, compounds 7 to 10, and 12 had MICs that were >100 µg/mL. Tsaokol A (3) was the most active compound with MICs of 0.6 µg/mL and 1.4 µg/mL, respectively, against replicating and nonreplicating M. tuberculosis. These results are the first to illustrate the potency of tsaokol A (3) as a natural drug candidate with good selectivity for treating tuberculosis
Emulsion of Aqueous-Based Nonspherical Droplets in Aqueous Solutions by Single-Chain Surfactants: Templated Assembly by Nonamphiphilic Lyotropic Liquid Crystals in Water
Single-chain surfactants usually emulsify and stabilize
oily substances
into droplets in an aqueous solution. Here, we report a coassembly
system, in which single types of anionic or non-ionic surfactants
emulsify a class of water-soluble nonamphiphilic organic salts with
fused aromatic rings in aqueous solutions. The nonamphiphilic organic
salts are in turn promoted to form droplets of water-based liquid
crystals (chromonic liquid crystals) encapsulated by single-chain
surfactants. The droplets, stabilized against coalescence by encapsulated
in a layer (or layers) of single chain surfactants, are of both nonspherical
tactoid (elongated ellipsoid with pointy ends) and spherical shapes.
The tactoids have an average long axis of ∼9 μm and a
short axis of ∼3.5 μm with the liquid crystal aligning
parallel to the droplet surface. The spherical droplets are 5–10
μm in diameter and have the liquid crystal aligning perpendicular
to the droplet surface and a point defect in the center. Cationic
and zwitterionic surfactants studied in this work did not promote
the organic salt to form droplets. These results illustrate the complex
interplay of self-association and thermodynamic incompatibility of
molecules in water, which can cause new assembly behavior, including
potential formation of vesicles or other assemblies, from surfactants
that usually form only micelles. These unprecedented tactoidal shaped
droplets also provide potential for the fabrication of new soft organic
microcapsules
Anti-Microbial Activity of Aliphatic Alcohols from Chinese Black Cardamom (Amomum tsao-ko) against Mycobacterium tuberculosis H37Rv
The fruits of Amomun tsao-ko (Chinese black cardamom; Zingiberaceae) contain an abundance of essential oils, which have previously demonstrated significant antimicrobial activity. In our preliminary search for natural anti-tuberculosis agents, an acetone extract of A. tsao-ko (AAE) exhibited strong antibacterial activity against Mycobacterium tuberculosis H37Rv. Therefore, the aim of this study was to find the principal compounds in an AAE against M. tuberculosis. Nine aliphatic compounds (1–9) including a new compound (1, tsaokol B) and a new natural unsaturated aliphatic diester (6), together with three acyclic terpenoids (10–12), were isolated from an AAE by repetitive chromatography. The structures of the isolates were determined by spectroscopic data analysis. All isolates were evaluated for activity against M. tuberculosis H37Rv. Isolated compounds 1–6, and 11 had MICs ranging from 0.6–89 µg/mL. In contrast, compounds 7 to 10, and 12 had MICs that were >100 µg/mL. Tsaokol A (3) was the most active compound with MICs of 0.6 µg/mL and 1.4 µg/mL, respectively, against replicating and nonreplicating M. tuberculosis. These results are the first to illustrate the potency of tsaokol A (3) as a natural drug candidate with good selectivity for treating tuberculosis