Pharmacophore Identification and Structure-Activity Relationship Analysis of a Series of Substituted Azaindoles as Inhibitors of .

Human African trypanosomiasis is among the World Health Organization's designated neglected tropical diseases. Repurposing strategies are often employed in academic drug discovery programs due to financial limitations, and in this instance, we used human kinase inhibitor chemotypes to identify substituted 4-aminoazaindoles, exemplified by . Structure-activity and structure-property relationship analysis, informed by cheminformatics, identified as a potent inhibitor of growth.

Corrigendum: Identification of novel anti-amoebic pharmacophores from kinase inhibitor chemotypes.

[This corrects the article DOI: 10.3389/fmicb.2023.

Structure-Property Optimization of a Series of Imidazopyridines for Visceral Leishmaniasis.

Leishmaniasis is a collection of diseases caused by more than 20 parasite species that manifest as either visceral, cutaneous, or mucocutaneous leishmaniasis. Despite the significant mortality and morbidity associated with leishmaniasis, it remains a neglected tropical disease. Existing treatments have variable efficacy, significant toxicity, rising resistance, and limited oral bioavailability, which necessitates the development of novel and affordable therapeutics.

Identification of novel anti-amoebic pharmacophores from kinase inhibitor chemotypes.

species, , and are opportunistic pathogens that cause a range of brain, skin, eye, and disseminated diseases in humans and animals. These pathogenic free-living amoebae (pFLA) are commonly misdiagnosed and have sub-optimal treatment regimens which contribute to the extremely high mortality rates (>90%) when they infect the central nervous system. To address the unmet medical need for effective therapeutics, we screened kinase inhibitor chemotypes against three pFLA using phenotypic drug assays involving CellTiter-Glo 2.

Synthesis of a DNA-Encoded Macrocyclic Library Utilizing Intramolecular Benzimidazole Formation.

Macrocycles occupy chemical space "beyond the rule of five". They bridge traditional bioactive small molecule drugs and macromolecules and have the potential to modulate challenging targets such as PPI or proteases. Here we report an on-DNA macrocyclization reaction utilizing intramolecular benzimidazole formation.

Chemical Optimization of CBL0137 for Human African Trypanosomiasis Lead Drug Discovery.

The carbazole CBL0137 () is a lead for drug development against human African trypanosomiasis (HAT), a disease caused by . To advance as a candidate drug, we synthesized new analogs that were evaluated for the physicochemical properties, antitrypanosome potency, selectivity against human cells, metabolism in microsomes or hepatocytes, and efflux ratios. Structure-activity/property analyses of analogs revealed eight new compounds with higher or equivalent selectivity indices (, , , , , , , and ).

Physiologic Targets and Modes of Action for CBL0137, a Lead for Human African Trypanosomiasis Drug Development.

CBL0137 is a lead drug for human African trypanosomiasis, caused by Herein, we use a four-step strategy to 1) identify physiologic targets and 2) determine modes of molecular action of CBL0137 in the trypanosome. First, we identified fourteen CBL0137-binding proteins using affinity chromatography. Second, we developed hypotheses of molecular modes of action, using predicted functions of CBL0137-binding proteins as guides.

Application of l-Threonine Aldolase to on-DNA Reactions.

Enzymatic catalysis is a highly attractive approach to the DNA encoded library technology (DEL) that has not been widely explored. In this paper, we report an l-threonine aldolase (l-TA)-catalyzed on-DNA aldol reaction to form β-hydroxy-α-amino acids, and its diastereoselectivity determination. l-TAs from three species show good on-DNA aldehyde scope and complementary stereoselectivity.

Lead Optimization of 3,5-Disubstituted-7-Azaindoles for the Treatment of Human African Trypanosomiasis.

Neglected tropical diseases such as human African trypanosomiasis (HAT) are prevalent primarily in tropical climates and among populations living in poverty. Historically, the lack of economic incentive to develop new treatments for these diseases has meant that existing therapeutics have serious shortcomings in terms of safety, efficacy, and administration, and better therapeutics are needed. We now report a series of 3,5-disubstituted-7-azaindoles identified as growth inhibitors of , the parasite that causes HAT, through a high-throughput screen.

Structure-property studies of an imidazoquinoline chemotype with antitrypanosomal activity.

Human African trypanosomiasis is a neglected tropical disease (NTD) that is fatal if left untreated. Although approximately 13 million people live in moderate- to high-risk areas for infection, current treatments are plagued by problems with safety, efficacy, and emerging resistance. In an effort to fill the drug development pipeline for HAT, we have expanded previous work exploring the chemotype represented by the compound , with a particular focus on improvement of absorption, distribution, metabolism and elimination (ADME) properties.

Medicinal Chemistry Optimization of a Diaminopurine Chemotype: Toward a Lead for Inhibitors.

Human African trypanosomiasis (HAT), or sleeping sickness, is caused by the protozoan parasite and transmitted through the bite of infected tsetse flies. The disease is considered fatal if left untreated. To identify new chemotypes against , previously we identified 797 potent kinase-targeting inhibitors grouped into 59 clusters plus 53 singleton compounds with at least 100-fold selectivity over HepG2 cells.

Structure-Bioactivity Relationships of Lapatinib Derived Analogs against .

We recently reported a series of compounds for a solubility-driven optimization campaign of antitrypanosomal compounds. Extending a parasite-hopping approach to the series, a subset of compounds from this library has been cross-screened for activity against the metazoan flatworm parasite, . This study reports the identification and preliminary development of several potently bioactive compounds against adult schistosomes, one or more of which represent promising leads for further assessment and optimization.

Scaffold and Parasite Hopping: Discovery of New Protozoal Proliferation Inhibitors.

Utilizing a target repurposing and parasite-hopping approach, we tested a previously reported library of compounds that were active against , plus 31 new compounds, against a variety of protozoan parasites including , , and . This led to the discovery of several compounds with submicromolar activities and improved physicochemical properties that are early leads toward the development of chemotherapeutic agents against kinetoplastid diseases and malaria.

Selectivity and Physicochemical Optimization of Repurposed Pyrazolo[1,5-]pyridazines for the Treatment of Human African Trypanosomiasis.

From a high-throughput screen of 42 444 known human kinases inhibitors, a pyrazolo[1,5-]pyridazine scaffold was identified to begin optimization for the treatment of human African trypanosomiasis. Previously reported data for analogous compounds against human kinases GSK-3β, CDK-2, and CDK-4 were leveraged to try to improve the selectivity of the series, resulting in which showed selectivity for over these three human enzymes. In parallel, properties known to influence the absorption, distribution, metabolism, and excretion (ADME) profile of the series were optimized resulting in being progressed into an efficacy study in mice.

Hit-to-Lead Optimization of Benzoxazepinoindazoles As Human African Trypanosomiasis Therapeutics.

Human African trypanosomiasis (HAT) is a neglected tropical disease caused by infection with either of two subspecies of the parasite . Due to a lack of economic incentive to develop new drugs, current treatments have severe limitations in terms of safety, efficacy, and ease of administration. In an effort to develop new HAT therapeutics, we report the structure-activity relationships around for a series of benzoxazepinoindazoles previously identified through a high-throughput screen of human kinase inhibitors, and the subsequent experiments for HAT.

Evaluation of a class of isatinoids identified from a high-throughput screen of human kinase inhibitors as anti-Sleeping Sickness agents.

New treatments are needed for neglected tropical diseases (NTDs) such as Human African trypanosomiasis (HAT), Chagas disease, and schistosomiasis. Through a whole organism high-throughput screening campaign, we previously identified 797 human kinase inhibitors that grouped into 59 structural clusters and showed activity against T. brucei, the causative agent of HAT.

Improvement of Aqueous Solubility of Lapatinib-Derived Analogues: Identification of a Quinolinimine Lead for Human African Trypanosomiasis Drug Development.

Lapatinib, an approved epidermal growth factor receptor inhibitor, was explored as a starting point for the synthesis of new hits against Trypanosoma brucei, the causative agent of human African trypanosomiasis (HAT). Previous work culminated in 1 (NEU-1953), which was part of a series typically associated with poor aqueous solubility. In this report, we present various medicinal chemistry strategies that were used to increase the aqueous solubility and improve the physicochemical profile without sacrificing antitrypanosomal potency.

Anilinoquinoline based inhibitors of trypanosomatid proliferation.

We recently reported the medicinal chemistry re-optimization of a series of compounds derived from the human tyrosine kinase inhibitor, lapatinib, for activity against Plasmodium falciparum. From this same library of compounds, we now report potent compounds against Trypanosoma brucei brucei (which causes human African trypanosomiasis), T. cruzi (the pathogen that causes Chagas disease), and Leishmania spp.

Series of Alkynyl-Substituted Thienopyrimidines as Inhibitors of Protozoan Parasite Proliferation.

Discovery of new chemotherapeutic lead agents can be accelerated by optimizing chemotypes proven to be effective in other diseases to act against parasites. One such medicinal chemistry campaign has focused on optimizing the anilinoquinazoline drug lapatinib () and the alkynyl thieno[3,2-]pyrimidine hit GW837016X (NEU-391, ) into leads for antitrypanosome drugs. We now report the structure-activity relationship studies of and its analogs against , which causes human African trypanosomiasis (HAT).

Calcium-Dependent Protein Kinase 5 Is Required for Release of Egress-Specific Organelles in .

The human malaria parasite requires efficient egress out of an infected red blood cell for pathogenesis. This egress event is highly coordinated and is mediated by several signaling proteins, including the plant-like calcium-dependent protein kinase 5 (PfCDPK5). Knockdown of PfCDPK5 results in an egress block where parasites are trapped inside their host cells.

Optimization of Physicochemical Properties for 4-Anilinoquinoline Inhibitors of Plasmodium falciparum Proliferation.

We recently reported the medicinal chemistry reoptimization of a known human tyrosine kinase inhibitor, lapatinib, against a variety of parasites responsible for numerous tropical diseases, including human African trypanosomiasis ( Trypanosoma brucei), Chagas disease ( T. cruzi), Leishmaniasis ( Leishmania spp.), and malaria ( Plasmodium falciparum).

Fexinidazole: A New Drug for African Sleeping Sickness on the Horizon.

Decades after the last new chemical entity was added to the pharmacopeia for human African trypanosomiasis (or sleeping sickness), orally dosed fexinidazole stands poised to replace the current treatment regimen for Trypanosoma brucei gambiense infections, following a positive Phase 2/3 clinical trial.

Fluorinated Adenosine A Receptor Antagonists Inspired by Preladenant as Potential Cancer Immunotherapeutics.

Antagonism of the adenosine A receptor on T cells blocks the hypoxia-adenosinergic pathway to promote tumor rejection. Using an immunoassay based on the Concanavalin A mouse model, a series of A antagonists were studied and identified preladenant as a potent lead compound for development. Molecular modeling was employed to assist drug design and subsequent synthesis of analogs and those of tozadenant, including fluorinated polyethylene glycol PEGylated derivatives.

The Importance of Collaboration between Industry, Academics, and Nonprofits in Tropical Disease Drug Discovery.

Collaborations between academic, industrial, and nonprofit companies can provide sufficient impetus to propel projects that have little economic return; such projects are prevalent in tropical disease drug discovery. In these collaborations, each partner contributes a unique set of skills and technical expertise which is advantageous to the project as a whole. Highly product-focused processes and specialized expertise sets dominate industry groups.