Search

A potent, noncytotoxic indazole sulfonamide was identified by high-throughput screening of >100,000 synthetic compounds for activity against Mycobacterium tuberculosis (Mtb). This noncytotoxic compound did not directly inhibit cell wall biogenesis but triggered a slow lysis of Mtb cells as measured by release of intracellular green fluorescent protein (GFP). Isolation of resistant mutants followed by whole-genome sequencing showed an unusual gene amplification of a 40 gene region spanning from Rv3371 to Rv3411c and in one case a potential promoter mutation upstream of guaB2 (Rv3411c) encoding inosine monophosphate dehydrogenase (IMPDH). Subsequent biochemical validation confirmed direct inhibition of IMPDH by an uncompetitive mode of inhibition, and growth inhibition could be rescued by supplementation with guanine, a bypass mechanism for the IMPDH pathway. Beads containing immobilized indazole sulfonamides specifically interacted with IMPDH in cell lysates. X-ray crystallography of the IMPDH-IMP-inhibitor complex revealed that the primary interactions of these compounds with IMPDH were direct pi-pi interactions with the IMP substrate. Advanced lead compounds in this series with acceptable pharmacokinetic properties failed to show efficacy in acute or chronic murine models of tuberculosis (TB). Time-kill experiments in vitro suggest that sustained exposure to drug concentrations above the minimum inhibitory concentration (MIC) for 24 h were required for a cidal effect, levels that have been difficult to achieve in vivo. Direct measurement of guanine levels in resected lung tissue from tuberculosis-infected animals and patients revealed 0.5-2 mM concentrations in caseum and normal lung tissue. The high lesional levels of guanine and the slow lytic, growth-rate-dependent effect of IMPDH inhibition pose challenges to developing drugs against this target for use in treating TB.

Background CAB+RPV LA administered monthly for HIV treatment is non-inferior to daily oral ART at maintaining HIV suppression but concerns about implementation of this novel treatment paradigm remain. CUSTOMIZE, an implementation-effectiveness study, examined barriers and facilitators to successful implementation of CAB+RPV LA in US HIV clinics. Methods Semi-structured qualitative interviews were conducted with physicians, injectors, and administrators across diverse clinics in US without previous CAB+RPV LA experience at Baseline (BL) (N=26) and after patients received the 4th monthly injection of CAB + RPV LA (interim) (N=24). Consolidated Framework for Implementation Research (CFIR) guided the interviews to evaluate barriers and facilitators to implementation. Interviews were recorded, transcribed, and coded using ATLAS.ti then analyzed for trends. Results At BL, 58% of study staff expected CAB+RPV LA would meet the needs of patients. Staff reported perceived advantages for patients: reduced stigma of pill bottles (38%), ability to live/travel in a “carefree” manner (31%) and removing the daily reminder of HIV (20%). At BL, most administrators had resource concerns: additional refrigeration, transportation, and staffing. Some clinics (38%) needed to purchase a refrigerator to store CAB+RPV LA. Some physicians noted a potential need for improved parking or expanded hours. At interim, most staff (71%) reported no change in official clinic hours; but 50% of injectors and 38% of administrators reported changing work hours to accommodate injection visits before clinic or at lunchtime. Existing appointment reminder systems and transportation support were reported as facilitators to implementation. Many staff (46%) noted additional visits increased coordination of other care needs. Most staff (67%) noted high patient acceptance and positive attitudes facilitated successful implementation of CAB + RPV LA. Conclusion Some staff had concerns about implementation initially, but at study interim minimal practice changes were needed to operationalize CAB+RPV LA effectively. Patient interest heightened staff desire to implement CAB+RPV LA in their clinics. Staff are optimistic that monthly CAB+RPV LA is manageable with minimal disruption to routine care in US HIV care settings. Disclosures Maggie Czarnogorski, MD, MPH, ViiV Healthcare (Employee) Cindy Garris, MSPH, GlaxoSmithKline (Other Financial or Material Support, Stockholder)ViiV Healthcare (Employee) Paul Wannamaker, BA, ViiV Healthcare (Employee) Ronald D’Amico, DO, MSc, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Carolyn Selenski, PhD, GSK (Employee, Shareholder) Colleen A. McHorney, PhD, Evidera (Employee) Larissa Stassek, MPH, Evidera (Employee) Gary I. Sinclair, MD, ViiV (Speaker’s Bureau) Leandro A. Mena, MD, MPH, Binx Health (Grant/Research Support)Evofem (Grant/Research Support)Gilead Science (Consultant, Grant/Research Support, Speaker’s Bureau)GSK (Grant/Research Support)Janssen (Grant/Research Support)Merck (Consultant, Grant/Research Support)Roche Molecular (Consultant, Grant/Research Support)SpeedDx (Grant/Research Support)ViiV Healthcare (Consultant, Grant/Research Support, Speaker’s Bureau) David Margolis, MD, MPH, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee)

Phenotypic screens for bactericidal compounds are starting to yield promising hits against tuberculosis. In this regard, whole-genome sequencing of spontaneous resistant mutants generated against an indazole sulfonamide (GSK3011724A) identifies several specific single-nucleotide polymorphisms in the essential Mycobacterium tuberculosis β-ketoacyl synthase (kas) A gene. Here, this genomic-based target assignment is confirmed by biochemical assays, chemical proteomics and structural resolution of a KasA-GSK3011724A complex by X-ray crystallography. Finally, M. tuberculosis GSK3011724A-resistant mutants increase the in vitro minimum inhibitory concentration and the in vivo 99% effective dose in mice, establishing in vitro and in vivo target engagement. Surprisingly, the lack of target engagement of the related β-ketoacyl synthases (FabH and KasB) suggests a different mode of inhibition when compared with other Kas inhibitors of fatty acid biosynthesis in bacteria. These results clearly identify KasA as the biological target of GSK3011724A and validate this enzyme for further drug discovery efforts against tuberculosis., Screens for bactericidal compounds have resulted in promising anti-tubercular hits. Here, the authors analyse in detail the target of an indazole sulfonamide (GSK3011724A), and find that it has a different mode of inhibition compared to other Kas inhibitors of fatty acid biosynthesis in bacteria.

We report the synthesis of diinsininone (33), the aglycone of (±)-diinsinin (2). Thereby, we complete the first construction of a proanthocyanidin (PA) type-A compound incorporating a [3.3.1]-bicyclic ketal as its characteristic core. Our strategy utilizes a coupling between a benzopyrilium salt and a flavanone that proves applicable to other PA type-A compounds. During this undertaking, treatment of naringenin (9) with 2-iodoxybenzoic acid (IBX) followed by reductive work-up affords eriodictyol (10). This reactivity mirrors that of catechol hydroxylase (F3H) found in the flavonoid pathway. Other interesting transformations include the formation of flavonoids through an ortho-quinone methide (o-QM) cycloaddition-oxidation sequence and regioselective β-glycosidations of several unprotected flavanones suggesting a likely synthesis of 2 from the aglycone 33.

The Diels-Alder reactions of o-quinone methides generated from OBOC-salicylic aldehydes and alcohols are described, allowing for the synthesis of various substituted benzopyrans. The low temperatures employed for this procedure enable high diastereoselectivity in reactions with beta-substituted o-quinone methides.

Malaria is a global health problem that causes significant mortality and morbidity, with more than 1 million deaths per year caused by P. falciparum. Most antimalarial drugs face decreased efficacy due to the spread of resistance. Most of the current compounds used for malaria treatment share related mechanisms of action so, there is an urgent need to identify new tractable targets to enable next generation of antimalarial drugs. The malaria drug discovery community has embraced phenotypic screening approaches as the strategy of choice for the generation of novel chemical starting points for Lead Optimization programs. Determining the mode of action for novel whole cell hits remains a challenge, but new technologies, including genetics, chemoinformatics and proteomics are proving successful. A chemical proteomics platform aimed at identifying antimalarial targets has been established. This platform is supported by The Bill & Melinda Gates Foundation and encompasses chemical probe synthesis, biological material preparation, pull down experiments and LC-MS protein-lead family characterization for chemical families of interest. Candidate scaffolds to be investigated through this platform are selected based on their biological profile by a join Steering Committee constituted by both GSK and BMGF members.

The first example of an enantioselective cycloaddition of an o-quinone methide (o-QM) with a chiral enol ether is described along with the total synthesis of (+)-mimosifoliol and the formal synthesis of (+)-tolterodine. These syntheses exemplify a three-component, one-pot benzopyran approach for the construction of chiral benzylic junctions. Cycloadditions of various enol ethers and o-QMs are examined, and diastereoselectivities >95% are obtained with trans-2-phenyl-1-cyclohexanol and 2,2-diphenylcyclopentanol vinyl ethers.