We identified an amino-benzothiazole scaffold from a whole-cell screen against recombinant Mycobacterium tuberculosis under expressing the essential signal peptidase LepB. The seed molecule had 2-fold higher activity against the LepB hypomorph. Through a combination of purchase and chemical synthesis, we explored the structure-activity relationship for this series; 34 analogs were tested for antitubercular activity and for cytotoxicity against eukaryotic cells. We identified molecules with improved potency and reduced cytotoxicity. However, molecules did not appear to target LepB directly and did not inhibit protein secretion. Key compounds showed good permeability, low protein binding, and lack of CYP inhibition, but metabolic stability was poor with short half-lives. The seed molecule showed good bactericidal activity against both replicating and nonreplicating bacteria, as well as potency against intracellular M. tuberculosis in murine macrophages. Overall, the microbiological properties of the series are attractive if metabolic stability can be improved, and identification of the target could assist in the development of this series. IMPORTANCE Mycobacterium tuberculosis, the causative agent of tuberculosis, is a serious global health problem requiring the development of new therapeutics. We previously ran a high-throughput screen and identified a series of compounds with antitubercular activity. In this paper, we test analogs of our hit molecules for activity against M. tuberculosis, as well as for activity against eukaryotic cells. We identified molecules with improved selectivity. Our molecules killed both replicating and nonreplicating bacteria but did not work by targeting protein secretion.
Mycobacterium tuberculosis , Tuberculosis , Animals , Mice , Mycobacterium tuberculosis/metabolism , Antitubercular Agents/pharmacology , Antitubercular Agents/chemistry , Tuberculosis/drug therapy , Tuberculosis/microbiology , Structure-Activity Relationship , Protein Binding , Microbial Sensitivity Tests
Dolutegravir (DTG), an important active pharmaceutical ingredient (API) used in combination therapy for the treatment of HIV, has been synthesized in continuous flow. By adapting the reported GlaxoSmithKline process chemistry batch route for Cabotegravir, DTG was produced in 4.5â h in sequential flow operations from commercially available materials. Key features of the synthesis include rapid manufacturing time for pyridone formation, one-step direct amidation of a functionalized pyridone, and telescoping of multiple steps to avoid isolation of intermediates and enable for greater throughput.
HIV Integrase Inhibitors/chemical synthesis , Heterocyclic Compounds, 3-Ring/chemical synthesis , Amides/chemical synthesis , Amides/chemistry , Combinatorial Chemistry Techniques/economics , Combinatorial Chemistry Techniques/methods , HIV Infections/drug therapy , HIV Integrase Inhibitors/chemistry , Heterocyclic Compounds, 3-Ring/chemistry , Humans , Oxazines , Piperazines , Pyridones/chemical synthesis , Pyridones/chemistry , Time Factors
The general secretion (Sec) pathway is a conserved essential pathway in bacteria and is the primary route of protein export across the cytoplasmic membrane. During protein export, the signal peptidase LepB catalyzes the cleavage of the signal peptide and subsequent release of mature proteins into the extracellular space. We developed a target-based whole cell assay to screen for potential inhibitors of LepB, the sole signal peptidase in Mycobacterium tuberculosis, using a strain engineered to underexpress LepB (LepB-UE). We screened 72,000 compounds against both the Lep-UE and wild-type (wt) strains. We identified the phenylhydrazone (PHY) series as having higher activity against the LepB-UE strain. We conducted a limited structure-activity relationship determination around a representative PHY compound with differential activity (MICs of 3.0 µM against the LepB-UE strain and 18 µM against the wt); several analogues were less potent against the LepB overexpressing strain. A number of chemical modifications around the hydrazone moiety resulted in improved potency. Inhibition of LepB activity was observed for a number of compounds in a biochemical assay using cell membrane fraction derived from M. tuberculosis. Compounds did not increase cell permeability, dissipate membrane potential, or inhibit an unrelated mycobacterial enzyme, suggesting a specific mode of action related to the LepB secretory mechanism.
Antitubercular Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Membrane Proteins/antagonists & inhibitors , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/enzymology , Antitubercular Agents/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Enzyme Inhibitors/chemistry , Humans , Kinetics , Membrane Proteins/genetics , Membrane Proteins/metabolism , Microbial Sensitivity Tests , Mycobacterium tuberculosis/chemistry , Mycobacterium tuberculosis/genetics , Serine Endopeptidases/genetics , Serine Endopeptidases/metabolism , Structure-Activity Relationship , Tuberculosis/microbiology
Polymer chemistry has embraced multicomponent reactions for synthesizing multifunctional materials, including structurally perfect multimodal dendrimers. An unexpected substituent effect dramatically shortens the time required for the convergent synthesis of dendrimers via the Passerini three-component reaction.
Tuning properties by programming the surface functional group composition of surface-block dendrimers has been limited to dendrimers with only two types of surface functionality (i.e., surface-diblock dendrimers). The Passerini reaction provides dendrimer products from precursor dendrons in reasonable yields. This proof-of-principle experiment opens the door to making surface-triblock dendrimers.
