Identification of small molecule inhibitors of pre-mRNA splicing

Background: There is a need for new small molecule pre-mRNA splicing inhibitors as biotools. Results: High throughput screening resulted in the identification of small molecule splicing inhibitors that are active in vitro and in cells. Conclusion: New small molecules for studying pre-mRNA splicing in vitro and in cells are identified. Significance: Small drug-like molecules are identified that modulate splicing in vitro and in cells. Eukaryotic pre-mRNA splicing is an essential step in gene expression for all genes that contain introns. In contrast to transcription and translation, few well characterized chemical inhibitors are available with which to dissect the splicing process, particularly in cells. Therefore, the identification of specific small molecules that either inhibit or modify pre-mRNA splicing would be valuable for research and potentially also for therapeutic applications. We have screened a highly curated library of 71,504 drug-like small molecules using a high throughput in vitro splicing assay. This identified 10 new compounds that both inhibit pre-mRNA splicing in vitro and modify splicing of endogenous pre-mRNA in cells. One of these splicing modulators, DDD00107587 (termed madrasin, i.e. 2-((7methoxy-4-methylquinazolin-2-yl)amino)-5,6-dimethylpyrimidin-4(3H)-one RNAsplicing inhibitor), was studied in more detail. Madrasin interferes with the early stages of spliceosome assembly and stalls spliceosome assembly at the A complex. Madrasin is cytotoxic at higher concentrations, although at lower concentrations it induces cell cycle arrest, promotes a specific reorganization of subnuclear protein localization, and modulates splicing of multiple pre-mRNAs in both HeLa and HEK293 cells

Undelivered risk: A counter-factual analysis of the biosecurity risk avoided by inspecting international mail articles

International mail articles present an important potential vector for biosecurity and other regulatory risk. Border intervention is a key element in Australia’s biosecurity strategy. Arriving international mail articles are inspected and those that are intercepted with biosecurity risk material are documented, including the address to which the article was to be delivered. Knowledge about patterns in the intended destinations of mail article permits more detailed biosecurity intervention. We used geo-location software to identify the delivery address of mail articles intercepted with biosecurity risk material from 2008–2011. We matched these addresses with demographic data that were recorded at a regional level from the Australian Bureau of Statistics 2011 Census and used random forest statistical analyses to correlate various demographic fields at the regional level with the counts of seized mail articles. The analysis of the seizure counts against demographic characteristics suggests a high correlation between having higher numbers of university students that speak a particular language in a region and higher quantities of intercepted mail articles destined for that region. We also explore metropolitan and regional patterns in the destinations of seized materials. These results can be used to provide information on policy and operational actions to try to reduce the rate at which mail articles that contain biosecurity risk material are sent to Australia

Screening a protein kinase inhibitor library against <i>Plasmodium falciparum</i>

Abstract Background Protein kinases have been shown to be key drug targets, especially in the area of oncology. It is of interest to explore the possibilities of protein kinases as a potential target class in Plasmodium spp., the causative agents of malaria. However, protein kinase biology in malaria is still being investigated. Therefore, rather than assaying against individual protein kinases, a library of 4731 compounds with protein kinase inhibitor-like scaffolds was screened against the causative parasite, Plasmodium falciparum. This approach is more holistic and considers the whole kinome, making it possible to identify compounds that inhibit more than one P. falciparum protein kinase, or indeed other malaria targets. Results As a result of this screen, 9 active compound series were identified; further validation was carried out on 4 of these series, with 3 being progressed into hits to lead chemistry. The detailed evaluation of one of these series is described. Discussion This screening approach proved to be an effective way to identify series for further optimisation against malaria. Compound optimisation was carried out in the absence of knowledge of the molecular target. Some of the series had to be halted for various reasons. Mode of action studies to find the molecular target may be useful when problems prevent further chemical optimisation. Conclusions Progressible series were identified through phenotypic screening of a relatively small focused kinase scaffold chemical library

Development of a 2,4-diaminothiazole series for the treatment of human African trypanosomiasis highlights the importance of static-cidal screening of analogues

While treatment options for human African trypanosomiasis (HAT) have improved significantly, there is still a need for new drugs with eradication now a realistic possibility. Here, we report the development of 2,4-diaminothiazoles that demonstrate significant potency against Trypanosoma brucei, the causative agent of HAT. Using phenotypic screening to guide structure-activity relationships, potent drug-like inhibitors were developed. Proof of concept was established in an animal model of the hemolymphatic stage of HAT. To treat the meningoencephalitic stage of infection, compounds were optimized for pharmacokinetic properties, including blood-brain barrier penetration. However, in vivo efficacy was not achieved, in part due to compounds evolving from a cytocidal to a cytostatic mechanism of action. Subsequent studies identified a nonessential kinase involved in the inositol biosynthesis pathway as the molecular target of these cytostatic compounds. These studies highlight the need for cytocidal drugs for the treatment of HAT and the importance of static-cidal screening of analogues

Identification of GSK3186899/DDD853651 as a Preclinical Development Candidate for the Treatment of Visceral Leishmaniasis

The leishmaniases are diseases that affect millions of people across the world, in particular visceral leishmaniasis (VL) which is fatal unless treated. Current standard of care for VL suffers from multiple issues and there is a limited pipeline of new candidate drugs. As such, there is a clear unmet medical need to identify new treatments. This paper describes the optimization of a phenotypic hit against Leishmania donovani, the major causative organism of VL. The key challenges were to balance solubility and metabolic stability while maintaining potency. Herein, strategies to address these shortcomings and enhance efficacy are discussed, culminating in the discovery of preclinical development candidate GSK3186899/DDD853651 (<b>1</b>) for VL

Anionic-oxy cope rearrangement of vinylsulfides and enol ethers

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