Publications by authors named "Susan A Charman"

151 Publications

Cytochrome P450-Mediated Metabolism and CYP Inhibition for the Synthetic Peroxide Antimalarial OZ439.

ACS Infect Dis 2021 Jun 8. Epub 2021 Jun 8.

Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia.

OZ439 is a potent synthetic ozonide evaluated for the treatment of uncomplicated malaria. The metabolite profile of OZ439 was characterized using human liver microsomes combined with LC/MS-MS, chemical derivatization, and metabolite synthesis. The primary biotransformations were monohydroxylation at the three distal carbon atoms of the spiroadamantane substructure, with minor contributions from -oxidation of the morpholine nitrogen and deethylation cleavage of the morpholine ring. Secondary transformations resulted in the formation of dihydroxylation metabolites and metabolites containing both monohydroxylation and morpholine -oxidation. With the exception of two minor metabolites, none of the other metabolites had appreciable antimalarial activity. Reaction phenotyping indicated that CYP3A4 is the enzyme responsible for the metabolism of OZ439, and it was found to inhibit CYP3A via both direct and mechanism-based inhibition. Elucidation of the metabolic pathways and kinetics will assist with efforts to predict potential metabolic drug-drug interactions and support physiologically based pharmacokinetic (PBPK) modeling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsinfecdis.1c00225DOI Listing
June 2021

Repositioning and Characterization of 1-(Pyridin-4-yl)pyrrolidin-2-one Derivatives as Cytoplasmic Prolyl-tRNA Synthetase Inhibitors.

ACS Infect Dis 2021 Jun 30;7(6):1680-1689. Epub 2021 Apr 30.

Medicines for Malaria Venture, ICC, Route de Pré-Bois 20, 1215 Geneva, Switzerland.

Prolyl-tRNA synthetase (PRS) is a clinically validated antimalarial target. Screening of a set of PRS ATP-site binders, initially designed for human indications, led to identification of 1-(pyridin-4-yl)pyrrolidin-2-one derivatives representing a novel antimalarial scaffold. Evidence designates cytoplasmic PRS as the drug target. The frontrunner and its active enantiomer exhibited low-double-digit nanomolar activity against resistant () laboratory strains and development of liver schizonts. No cross-resistance with strains resistant to other known antimalarials was noted. In addition, a similar level of growth inhibition was observed against clinical field isolates of and . The slow killing profile and the relative high propensity to develop resistance (minimum inoculum resistance of 8 × 10 parasites at a selection pressure of 3 × IC) constitute unfavorable features for treatment of malaria. However, potent blood stage and antischizontal activity are compelling for causal prophylaxis which does not require fast onset of action. Achieving sufficient on-target selectivity appears to be particularly challenging and should be the primary focus during the next steps of optimization of this chemical series. Encouraging preliminary off-target profile and oral efficacy in a humanized murine model of malaria allowed us to conclude that 1-(pyridin-4-yl)pyrrolidin-2-one derivatives represent a promising starting point for the identification of novel antimalarial prophylactic agents that selectively target PRS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsinfecdis.1c00020DOI Listing
June 2021

Potent Antimalarials with Development Potential Identified by Structure-Guided Computational Optimization of a Pyrrole-Based Dihydroorotate Dehydrogenase Inhibitor Series.

J Med Chem 2021 05 20;64(9):6085-6136. Epub 2021 Apr 20.

Infectious Diseases Research Collaboration, Kampala, Uganda.

Dihydroorotate dehydrogenase (DHODH) has been clinically validated as a target for the development of new antimalarials. Experience with clinical candidate triazolopyrimidine DSM265 () suggested that DHODH inhibitors have great potential for use in prophylaxis, which represents an unmet need in the malaria drug discovery portfolio for endemic countries, particularly in areas of high transmission in Africa. We describe a structure-based computationally driven lead optimization program of a pyrrole-based series of DHODH inhibitors, leading to the discovery of two candidates for potential advancement to preclinical development. These compounds have improved physicochemical properties over prior series frontrunners and they show no time-dependent CYP inhibition, characteristic of earlier compounds. Frontrunners have potent antimalarial activity against blood and liver schizont stages and show good efficacy in SCID mouse models. They are equally active against and field isolates and are selective for DHODHs versus mammalian enzymes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.1c00173DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8171248PMC
May 2021

Systematic evaluation of structure-property relationships and pharmacokinetics in 6-(hetero)aryl-substituted matched pair analogs of amiloride and 5-(N,N-hexamethylene)amiloride.

Bioorg Med Chem 2021 May 23;37:116116. Epub 2021 Mar 23.

Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia; CONCERT-Translational Cancer Research Centre, NSW 2750, Australia.

The K-sparing diuretic amiloride elicits anticancer activities in multiple animal models. During our recent medicinal chemistry campaign aiming to identify amiloride analogs with improved properties for potential use in cancer, we discovered novel 6-(hetero)aryl-substituted amiloride and 5-(N,N-hexamethylene)amiloride (HMA) analogs with up to 100-fold higher potencies than the parent compounds against urokinase plasminogen activator (uPA), one of amiloride's putative anticancer targets, and no diuretic or antikaliuretic effects. Here, we report the systematic evaluation of structure-property relationships (lipophilicity, aqueous solubility and in vitro metabolic stability in human and mouse liver microsomes) in twelve matched pair analogs selected from our 6-substituted amiloride and HMA libraries. Mouse plasma stability, plasma protein binding, Caco-2 cell permeability, cardiac ion channel activity and pharmacokinetics in mice (PO and IV) and rats (IV) are described alongside amiloride and HMA comparators for a subset of the four most promising matched-pair analogs. The findings combined with earlier uPA activity/selectivity and other data ultimately drove selection of two analogs (AA1-39 and AA1-41) that showed efficacy in separate mouse cancer metastasis studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmc.2021.116116DOI Listing
May 2021

Discovery of Potent and Fast-Acting Antimalarial Bis-1,2,4-triazines.

J Med Chem 2021 04 24;64(7):4150-4162. Epub 2021 Mar 24.

Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052, Australia.

Novel 3,3'-disubstituted-5,5'-bi(1,2,4-triazine) compounds with potent activity against parasites were recently discovered. To improve the pharmacokinetic properties of the triazine derivatives, a new structure-activity relationship (SAR) investigation was initiated with a focus on enhancing the metabolic stability of lead compounds. These efforts led to the identification of second-generation highly potent antimalarial bis-triazines, exemplified by triazine , which exhibited significantly improved metabolic stability (8 and 42 μL/min/mg protein in human and mouse liver microsomes). The disubstituted triazine dimer was also observed to suppress parasitemia in the Peters 4-day test with a mean ED value of 1.85 mg/kg/day and exhibited a fast-killing profile, revealing a new class of orally available antimalarial compounds of considerable interest.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.1c00044DOI Listing
April 2021

Preclinical small molecule WEHI-7326 overcomes drug resistance and elicits response in patient-derived xenograft models of human treatment-refractory tumors.

Cell Death Dis 2021 Mar 12;12(3):268. Epub 2021 Mar 12.

Walter and Eliza Hall Institute, Parkville, VIC, 3052, Australia.

Targeting cell division by chemotherapy is a highly effective strategy to treat a wide range of cancers. However, there are limitations of many standard-of-care chemotherapies: undesirable drug toxicity, side-effects, resistance and high cost. New small molecules which kill a wide range of cancer subtypes, with good therapeutic window in vivo, have the potential to complement the current arsenal of anti-cancer agents and deliver improved safety profiles for cancer patients. We describe results with a new anti-cancer small molecule, WEHI-7326, which causes cell cycle arrest in G2/M, cell death in vitro, and displays efficacious anti-tumor activity in vivo. WEHI-7326 induces cell death in a broad range of cancer cell lines, including taxane-resistant cells, and inhibits growth of human colon, brain, lung, prostate and breast tumors in mice xenografts. Importantly, the compound elicits tumor responses as a single agent in patient-derived xenografts of clinically aggressive, treatment-refractory neuroblastoma, breast, lung and ovarian cancer. In combination with standard-of-care, WEHI-7326 induces a remarkable complete response in a mouse model of high-risk neuroblastoma. WEHI-7326 is mechanistically distinct from known microtubule-targeting agents and blocks cells early in mitosis to inhibit cell division, ultimately leading to apoptotic cell death. The compound is simple to produce and possesses favorable pharmacokinetic and toxicity profiles in rodents. It represents a novel class of anti-cancer therapeutics with excellent potential for further development due to the ease of synthesis, simple formulation, moderate side effects and potent in vivo activity. WEHI-7326 has the potential to complement current frontline anti-cancer drugs and to overcome drug resistance in a wide range of cancers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41419-020-03269-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7955127PMC
March 2021

Novel Antimalarial Tetrazoles and Amides Active against the Hemoglobin Degradation Pathway in .

J Med Chem 2021 03 23;64(5):2739-2761. Epub 2021 Feb 23.

Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States.

Malaria control programs continue to be threatened by drug resistance. To identify new antimalarials, we conducted a phenotypic screen and identified a novel tetrazole-based series that shows fast-kill kinetics and a relatively low propensity to develop high-level resistance. Preliminary structure-activity relationships were established including identification of a subseries of related amides with antiplasmodial activity. Assaying parasites with resistance to antimalarials led us to test whether the series had a similar mechanism of action to chloroquine (CQ). Treatment of synchronized parasites with active analogues revealed a pattern of intracellular inhibition of hemozoin (Hz) formation reminiscent of CQ's action. Drug selections yielded only modest resistance that was associated with amplification of the multidrug resistance gene 1 (). Thus, we have identified a novel chemical series that targets the historically druggable heme polymerization pathway and that can form the basis of future optimization efforts to develop a new malaria treatment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.0c02022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7997635PMC
March 2021

Selecting an anti-malarial clinical candidate from two potent dihydroisoquinolones.

Malar J 2021 Feb 19;20(1):107. Epub 2021 Feb 19.

Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, KY, 40536, USA.

Background: The ongoing global malaria eradication campaign requires development of potent, safe, and cost-effective drugs lacking cross-resistance with existing chemotherapies. One critical step in drug development is selecting a suitable clinical candidate from late leads. The process used to select the clinical candidate SJ733 from two potent dihydroisoquinolone (DHIQ) late leads, SJ733 and SJ311, based on their physicochemical, pharmacokinetic (PK), and toxicity profiles is described.

Methods: The compounds were tested to define their physicochemical properties including kinetic and thermodynamic solubility, partition coefficient, permeability, ionization constant, and binding to plasma proteins. Metabolic stability was assessed in both microsomes and hepatocytes derived from mice, rats, dogs, and humans. Cytochrome P450 inhibition was assessed using recombinant human cytochrome enzymes. The pharmacokinetic profiles of single intravenous or oral doses were investigated in mice, rats, and dogs.

Results: Although both compounds displayed similar physicochemical properties, SJ733 was more permeable but metabolically less stable than SJ311 in vitro. Single dose PK studies of SJ733 in mice, rats, and dogs demonstrated appreciable oral bioavailability (60-100%), whereas SJ311 had lower oral bioavailability (mice 23%, rats 40%) and higher renal clearance (10-30 fold higher than SJ733 in rats and dogs), suggesting less favorable exposure in humans. SJ311 also displayed a narrower range of dose-proportional exposure, with plasma exposure flattening at doses above 200 mg/kg.

Conclusion: SJ733 was chosen as the candidate based on a more favorable dose proportionality of exposure and stronger expectation of the ability to justify a strong therapeutic index to regulators.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12936-021-03617-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7893776PMC
February 2021

Re-evaluating pretomanid analogues for Chagas disease: Hit-to-lead studies reveal both in vitro and in vivo trypanocidal efficacy.

Eur J Med Chem 2020 Dec 18;207:112849. Epub 2020 Sep 18.

Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.

Phenotypic screening of a 900 compound library of antitubercular nitroimidazole derivatives related to pretomanid against the protozoan parasite Trypanosoma cruzi (the causative agent for Chagas disease) identified several structurally diverse hits with an unknown mode of action. Following initial profiling, a first proof-of-concept in vivo study was undertaken, in which once daily oral dosing of a 7-substituted 2-nitroimidazooxazine analogue suppressed blood parasitemia to low or undetectable levels, although sterile cure was not achieved. Limited hit expansion studies alongside counter-screening of new compounds targeted at visceral leishmaniasis laid the foundation for a more in-depth assessment of the best leads, focusing on both drug-like attributes (solubility, metabolic stability and safety) and maximal killing of the parasite in a shorter timeframe. Comparative appraisal of one preferred lead (58) in a chronic infection mouse model, monitored by highly sensitive bioluminescence imaging, provided the first definitive evidence of (partial) curative efficacy with this promising nitroimidazooxazine class.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejmech.2020.112849DOI Listing
December 2020

Modulation of Lymphocyte Potassium Channel K1.3 by Membrane-Penetrating, Joint-Targeting Immunomodulatory Plant Defensin.

ACS Pharmacol Transl Sci 2020 Aug 14;3(4):720-736. Epub 2020 May 14.

School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.

We describe a cysteine-rich, membrane-penetrating, joint-targeting, and remarkably stable peptide, EgK5, that modulates voltage-gated K1.3 potassium channels in T lymphocytes by a distinctive mechanism. EgK5 enters plasma membranes and binds to K1.3, causing current run-down by a phosphatidylinositol 4,5-bisphosphate-dependent mechanism. EgK5 exhibits selectivity for K1.3 over other channels, receptors, transporters, and enzymes. EgK5 suppresses antigen-triggered proliferation of effector memory T cells, a subset enriched among pathogenic autoreactive T cells in autoimmune disease. PET-CT imaging with F-labeled EgK5 shows accumulation of the peptide in large and small joints of rodents. In keeping with its arthrotropism, EgK5 treats disease in a rat model of rheumatoid arthritis. It was also effective in treating disease in a rat model of atopic dermatitis. No signs of toxicity are observed at 10-100 times the dose. EgK5 shows promise for clinical development as a therapeutic for autoimmune diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsptsci.0c00035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7432667PMC
August 2020

Intestinal Lymph Flow, and Lipid and Drug Transport Scale Allometrically From Pre-clinical Species to Humans.

Front Physiol 2020 21;11:458. Epub 2020 May 21.

Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Parkville, VIC, Australia.

The intestinal lymphatic system transports fluid, immune cells, dietary lipids, and highly lipophilic drugs from the intestine to the systemic circulation. These transport functions are important to health and when dysregulated contribute to pathology. This has generated significant interest in approaches to deliver drugs to the lymphatics. Most of the current understanding of intestinal lymph flow, and lymphatic lipid and drug transport rates, comes from studies and animal studies. In contrast, intestinal lymphatic transport studies in human subjects have been limited. Recently, three surgical patients had cannulation of the thoracic lymph duct for collection of lymph before and during a stepwise increase in enteral feed rate. We compared these data to studies where we previously enterally administered controlled quantities of lipid and the lipophilic drug halofantrine to mice, rats and dogs and collected lymph and blood (plasma). The collected lymph was analyzed to compare lymph flow rate, triglyceride (TG) and drug transport rates, and plasma was analyzed for drug concentrations, as a function of enteral lipid dose across species. Lymph flow rate, TG and drug transport increased with lipid administration in all species tested, and scaled allometrically according to the equation A = M where A is the lymph transport parameter, M is animal body mass, is constant and is the allometric exponent. For lymph flow rate and TG transport, the allometric exponents were 0.84-0.94 and 0.80-0.96, respectively. Accordingly, weight normalized lymph flow and TG mass transport were generally lower in larger compared to smaller species. In comparison, mass transport of drug via lymph increased in a greater than proportional manner with species body mass with an exponent of ∼1.3. The supra-proportional increase in lymphatic drug transport with species body mass appeared to be due to increased partitioning of drug into lymph rather than blood following absorption. Overall, this study proposes that intestinal lymphatic flow, and lymphatic lipid and drug transport in humans is most similar to species with higher body mass such as dogs and underestimated by studies in rodents. Notably, lymph flow and lipid transport in humans can be predicted from animal data via allometric scaling suggesting the potential for similar relationships with drug transport.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fphys.2020.00458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7326060PMC
May 2020

Efficacy, metabolism and pharmacokinetics of Ro 15-5458, a forgotten schistosomicidal 9-acridanone hydrazone.

J Antimicrob Chemother 2020 10;75(10):2925-2932

Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, PO Box, CH-4002, Basel, Switzerland.

Background: Treatment of schistosomiasis, a neglected disease, relies on just one partially effective drug, praziquantel. We revisited the 9-acridanone hydrazone, Ro 15-5458, a largely forgotten antischistosomal lead compound.

Methods: Ro 15-5458 was evaluated in juvenile and adult Schistosoma mansoni-infected mice. We studied dose-response, hepatic shift and stage specificity. The metabolic stability of Ro 15-5458 was measured in the presence of human and mouse liver microsomes, and human hepatocytes; the latter also served to identify metabolites. Pharmacokinetic parameters were measured in naive mice. The efficacy of Ro 15-5458 was also assessed in S. haematobium-infected hamsters and S. japonicum-infected mice.

Results: Ro 15-5458 had single-dose ED50 values of 15 and 5.3 mg/kg in mice harbouring juvenile and adult S. mansoni infections, respectively. An ED50 value of 17 mg/kg was measured in S. haematobium-infected hamsters; however, the compound was inactive at up to 100 mg/kg in S. japonicum-infected mice. The drug-induced hepatic shift occurred between 48 and 66 h post treatment. A single oral dose of 50 mg/kg of Ro 15-5458 had high activity against all tested S. mansoni stages (1-, 7-, 14-, 21- and 49-day-old). In vitro, human hepatocytes produced N-desethyl and glucuronide metabolites; otherwise Ro 15-5458 was metabolically stable in the presence of microsomes or whole hepatocytes. The maximum plasma concentration was approximately 8.13 μg/mL 3 h after a 50 mg/kg oral dose and the half-life was approximately 4.9 h.

Conclusions: Ro 15-5458 has high activity against S. mansoni and S. haematobium, yet lacks activity against S. japonicum, which is striking. This will require further investigation, as a broad-spectrum antischistosomal drug is desirable.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/jac/dkaa247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556815PMC
October 2020

System-wide biochemical analysis reveals ozonide antimalarials initially act by disrupting Plasmodium falciparum haemoglobin digestion.

PLoS Pathog 2020 06 26;16(6):e1008485. Epub 2020 Jun 26.

Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.

Ozonide antimalarials, OZ277 (arterolane) and OZ439 (artefenomel), are synthetic peroxide-based antimalarials with potent activity against the deadliest malaria parasite, Plasmodium falciparum. Here we used a "multi-omics" workflow, in combination with activity-based protein profiling (ABPP), to demonstrate that peroxide antimalarials initially target the haemoglobin (Hb) digestion pathway to kill malaria parasites. Time-dependent metabolomic profiling of ozonide-treated P. falciparum infected red blood cells revealed a rapid depletion of short Hb-derived peptides followed by subsequent alterations in lipid and nucleotide metabolism, while untargeted peptidomics showed accumulation of longer Hb-derived peptides. Quantitative proteomics and ABPP assays demonstrated that Hb-digesting proteases were increased in abundance and activity following treatment, respectively. Ozonide-induced depletion of short Hb-derived peptides was less extensive in a drug-treated K13-mutant artemisinin resistant parasite line (Cam3.IIR539T) than in the drug-treated isogenic sensitive strain (Cam3.IIrev), further confirming the association between ozonide activity and Hb catabolism. To demonstrate that compromised Hb catabolism may be a primary mechanism involved in ozonide antimalarial activity, we showed that parasites forced to rely solely on Hb digestion for amino acids became hypersensitive to short ozonide exposures. Quantitative proteomics analysis also revealed parasite proteins involved in translation and the ubiquitin-proteasome system were enriched following drug treatment, suggestive of the parasite engaging a stress response to mitigate ozonide-induced damage. Taken together, these data point to a mechanism of action involving initial impairment of Hb catabolism, and indicate that the parasite regulates protein turnover to manage ozonide-induced damage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.ppat.1008485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347234PMC
June 2020

Lead Optimization of a Pyrrole-Based Dihydroorotate Dehydrogenase Inhibitor Series for the Treatment of Malaria.

J Med Chem 2020 05 16;63(9):4929-4956. Epub 2020 Apr 16.

Departments of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, Texas 75390-9135, United States.

Malaria puts at risk nearly half the world's population and causes high mortality in sub-Saharan Africa, while drug resistance threatens current therapies. The pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase (DHODH) is a validated target for malaria treatment based on our finding that triazolopyrimidine DSM265 () showed efficacy in clinical studies. Herein, we describe optimization of a pyrrole-based series identified using a target-based DHODH screen. Compounds with nanomolar potency versus DHODH and parasites were identified with good pharmacological properties. X-ray studies showed that the pyrroles bind an alternative enzyme conformation from leading to improved species selectivity versus mammalian enzymes and equivalent activity on and DHODH. The best lead DSM502 () showed efficacy at similar levels of blood exposure to , although metabolic stability was reduced. Overall, the pyrrole-based DHODH inhibitors provide an attractive alternative scaffold for the development of new antimalarial compounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.0c00311DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7394244PMC
May 2020

Structure-Activity Relationship of Antischistosomal Ozonide Carboxylic Acids.

J Med Chem 2020 04 19;63(7):3723-3736. Epub 2020 Mar 19.

College of Pharmacy, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, Nebraska 986125, United States.

Semisynthetic artemisinins and other bioactive peroxides are best known for their powerful antimalarial activities, and they also show substantial activity against schistosomes-another hemoglobin-degrading pathogen. Building on this discovery, we now describe the initial structure-activity relationship (SAR) of antischistosomal ozonide carboxylic acids OZ418 () and OZ165 (). Irrespective of lipophilicity, these ozonide weak acids have relatively low aqueous solubilities and high protein binding values. Ozonides with -substituted carboxymethoxy and -benzylglycine substituents had high antischistosomal efficacies. It was possible to increase solubility, decrease protein binding, and maintain the high antischistosomal activity in mice infected with juvenile and adult by incorporating a weak base functional group in these compounds. In some cases, adding polar functional groups and heteroatoms to the spiroadamantane substructure increased the solubility and metabolic stability, but in all cases decreased the antischistosomal activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.0c00069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182039PMC
April 2020

Discovery of Acylsulfonohydrazide-Derived Inhibitors of the Lysine Acetyltransferase, KAT6A, as Potent Senescence-Inducing Anti-Cancer Agents.

J Med Chem 2020 05 19;63(9):4655-4684. Epub 2020 Mar 19.

ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia.

A high-throughput screen designed to discover new inhibitors of histone acetyltransferase KAT6A uncovered CTX-0124143 (), a unique aryl acylsulfonohydrazide with an IC of 1.0 μM. Using this acylsulfonohydrazide as a template, we herein disclose the results of our extensive structure-activity relationship investigations, which resulted in the discovery of advanced compounds such as and . These two compounds represent significant improvements on our recently reported prototypical lead WM-8014 () as they are not only equivalently potent as inhibitors of KAT6A but are less lipophilic and significantly more stable to microsomal degradation. Furthermore, during this process, we discovered a distinct structural subclass that contains key 2-fluorobenzenesulfonyl and phenylpyridine motifs, culminating in the discovery of WM-1119 (). This compound is a highly potent KAT6A inhibitor (IC = 6.3 nM; = 0.002 μM), competes with Ac-CoA by binding to the Ac-CoA binding site, and has an oral bioavailability of 56% in rats.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.9b02071DOI Listing
May 2020

An in vitro toolbox to accelerate anti-malarial drug discovery and development.

Malar J 2020 Jan 2;19(1). Epub 2020 Jan 2.

Medicines for Malaria Venture, PO Box 1826, 20 Route de Pré-Bois, CH-1215, Geneva 15, Switzerland.

Background: Modelling and simulation are being increasingly utilized to support the discovery and development of new anti-malarial drugs. These approaches require reliable in vitro data for physicochemical properties, permeability, binding, intrinsic clearance and cytochrome P450 inhibition. This work was conducted to generate an in vitro data toolbox using standardized methods for a set of 45 anti-malarial drugs and to assess changes in physicochemical properties in relation to changing target product and candidate profiles.

Methods: Ionization constants were determined by potentiometric titration and partition coefficients were measured using a shake-flask method. Solubility was assessed in biorelevant media and permeability coefficients and efflux ratios were determined using Caco-2 cell monolayers. Binding to plasma and media proteins was measured using either ultracentrifugation or rapid equilibrium dialysis. Metabolic stability and cytochrome P450 inhibition were assessed using human liver microsomes. Sample analysis was conducted by LC-MS/MS.

Results: Both solubility and fraction unbound decreased, and permeability and unbound intrinsic clearance increased, with increasing Log D. In general, development compounds were somewhat more lipophilic than legacy drugs. For many compounds, permeability and protein binding were challenging to assess and both required the use of experimental conditions that minimized the impact of non-specific binding. Intrinsic clearance in human liver microsomes was varied across the data set and several compounds exhibited no measurable substrate loss under the conditions used. Inhibition of cytochrome P450 enzymes was minimal for most compounds.

Conclusions: This is the first data set to describe in vitro properties for 45 legacy and development anti-malarial drugs. The studies identified several practical methodological issues common to many of the more lipophilic compounds and highlighted areas which require more work to customize experimental conditions for compounds being designed to meet the new target product profiles. The dataset will be a valuable tool for malaria researchers aiming to develop PBPK models for the prediction of human PK properties and/or drug-drug interactions. Furthermore, generation of this comprehensive data set within a single laboratory allows direct comparison of properties across a large dataset and evaluation of changing property trends that have occurred over time with changing target product and candidate profiles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12936-019-3075-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941357PMC
January 2020

Ozonide Antimalarials Alkylate Heme in the Malaria Parasite .

ACS Infect Dis 2019 12 2;5(12):2076-2086. Epub 2019 Dec 2.

Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences , Monash University , 381 Royal Parade , Parkville , Victoria 3052 , Australia.

The mechanism of action of ozonide antimalarials involves activation by intraparasitic iron and the formation of highly reactive carbon-centered radicals that alkylate malaria parasite proteins. Given free intraparasitic heme is generally thought to be the iron source responsible for ozonide activation and its likely close proximity to the activated drug, we investigated heme as a possible molecular target of the ozonides. Using an extraction method optimized for solubilization of free heme, untargeted LC-MS analysis of ozonide-treated parasites identified several regioisomers of ozonide-alkylated heme, which resulted from covalent modification of the heme porphyrin ring by an ozonide-derived carbon-centered radical. In addition to the intact alkylated heme adduct, putative ozonide-alkylated heme degradation products were also detected. This study directly demonstrates ozonide modification of heme within the malaria parasite , revealing that this process may be important for the biological activity of ozonide antimalarials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsinfecdis.9b00257DOI Listing
December 2019

The Development Process for Discovery and Clinical Advancement of Modern Antimalarials.

J Med Chem 2019 12 20;62(23):10526-10562. Epub 2019 Aug 20.

The Walter and Eliza Hall Institute of Medical Research , Parkville , Victoria 3052 , Australia.

Malaria is a devastating disease caused by parasites, resulting in approximately 435000 deaths in 2018. The impact of malaria is compounded by the emergence of widespread resistance to current antimalarial therapies. Recently, a new strategy was initiated to screen small molecule collections against the parasite enabling the identification of new antimalarial chemotypes with novel modes of action. This initiative ushered in the modern era of antimalarial drug development, and as a result, numerous lead candidates are advancing toward or are currently in human clinical trials. In this Perspective, we describe the development pathway of four of the most clinically advanced modern antimalarials, KAE609, KAF156, DSM265, and MMV048. Additionally, the mechanism of action and life-cycle stage specificity of the four antimalarials is discussed in relation to aligning with global strategies to treat and eliminate malaria. This perspective serves as a guide to the expectations of modern antimalarial drug development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.9b00761DOI Listing
December 2019

Discovery of Benzoylsulfonohydrazides as Potent Inhibitors of the Histone Acetyltransferase KAT6A.

J Med Chem 2019 08 17;62(15):7146-7159. Epub 2019 Jul 17.

School of Pharmaceutical Sciences , Nanjing Tech University , No. 30 South Puzhu Road , Nanjing 211816 , People's Republic of China.

A high-throughput screen for inhibitors of the histone acetyltransferase, KAT6A, led to identification of an aryl sulfonohydrazide derivative (CTX-0124143) that inhibited KAT6A with an IC of 1.0 μM. Elaboration of the structure-activity relationship and medicinal chemistry optimization led to the discovery of WM-8014 (), a highly potent inhibitor of KAT6A (IC = 0.008 μM). WM-8014 competes with acetyl-CoA (Ac-CoA), and X-ray crystallographic analysis demonstrated binding to the Ac-CoA binding site. Through inhibition of KAT6A activity, WM-8014 induces cellular senescence and represents a unique pharmacological tool.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.9b00665DOI Listing
August 2019

Novel Human Aminopeptidase N Inhibitors: Discovery and Optimization of Subsite Binding Interactions.

J Med Chem 2019 08 18;62(15):7185-7209. Epub 2019 Jul 18.

Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology , Monash University , Clayton Campus , Clayton , VIC 3800 , Australia.

Aminopeptidase N (APN/CD13) is a zinc-dependent M1 aminopeptidase that contributes to cancer progression by promoting angiogenesis, metastasis, and tumor invasion. We have previously identified hydroxamic acid-containing analogues that are potent inhibitors of the APN homologue from the malarial parasite M1 aminopeptidase (A-M1). Herein, we describe the rationale that underpins the repurposing of A-M1 inhibitors as novel APN inhibitors. A series of novel hydroxamic acid analogues were developed using a structure-based design approach and evaluated their inhibition activities against APN. -(2-(Hydroxyamino)-2-oxo-1-(3',4',5'-trifluoro-[1,1'-biphenyl]-4-yl)ethyl)-4-(methylsulfonamido)benzamide () proved to be an extremely potent inhibitor of APN activity in vitro, selective against other zinc-dependent enzymes such as matrix metalloproteases, and possessed limited cytotoxicity against Ad293 cells and favorable physicochemical and metabolic stability properties. The combined results indicate that compound may be a useful lead for the development of anticancer agents.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.9b00757DOI Listing
August 2019

Ozonide Antimalarial Activity in the Context of Artemisinin-Resistant Malaria.

Trends Parasitol 2019 07 5;35(7):529-543. Epub 2019 Jun 5.

Drug Delivery, Disposition, and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Victoria, Australia. Electronic address:

The ozonides are one of the most advanced drug classes in the antimalarial development pipeline and were designed to improve on limitations associated with current front-line artemisinin-based therapies. Like the artemisinins, the pharmacophoric peroxide bond of ozonides is essential for activity, and it appears that these antimalarials share a similar mode of action, raising the possibility of cross-resistance. Resistance to artemisinins is associated with Plasmodium falciparum mutations that allow resistant parasites to escape short-term artemisinin-mediated damage (elimination half-life ~1 h). Importantly, some ozonides (e.g., OZ439) have a sustained in vivo drug exposure profile, providing a major pharmacokinetic advantage over the artemisinin derivatives. Here, we describe recent progress made towards understanding ozonide antimalarial activity and discuss ozonide utility within the context of artemisinin resistance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pt.2019.05.002DOI Listing
July 2019

Falcipain Inhibitors Based on the Natural Product Gallinamide A Are Potent in Vitro and in Vivo Antimalarials.

J Med Chem 2019 06 22;62(11):5562-5578. Epub 2019 May 22.

School of Chemistry , Building F11, The University of Sydney , Sydney , New South Wales 2006 , Australia.

A library of analogues of the cyanobacterium-derived depsipeptide natural product gallinamide A were designed and prepared using a highly efficient and convergent synthetic route. Analogues were shown to exhibit potent inhibitory activity against the Plasmodium falciparum cysteine proteases falcipain 2 and falcipain 3 and against cultured chloroquine-sensitive (3D7) and chloroquine-resistant (W2) strains of P. falciparum. Three lead compounds were selected for evaluation of in vivo efficacy against Plasmodium berghei infection in mice on the basis of their improved blood, plasma, and microsomal stability profiles compared with the parent natural product. One of the lead analogues cured P. berghei-infected mice in the Peters 4 day-suppressive test when administered 25 mg kg intraperitoneally daily for 4 days. The compound was also capable of clearing parasites in established infections at 50 mg kg intraperitoneally daily for 4 days and exhibited moderate activity when administered as four oral doses of 100 mg kg.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.9b00504DOI Listing
June 2019

3,3'-Disubstituted 5,5'-Bi(1,2,4-triazine) Derivatives with Potent in Vitro and in Vivo Antimalarial Activity.

J Med Chem 2019 03 5;62(5):2485-2498. Epub 2019 Mar 5.

School of Pharmaceutical Sciences , Nanjing Tech University , No. 30 South Puzhu Road , Nanjing 211816 , People's Republic of China.

A series of 3,3'-disubstituted 5,5'-bi(1,2,4-triazine) derivatives was synthesized and screened against the erythrocytic stage of Plasmodium falciparum 3D7 line. The most potent dimer, 6k, with an IC (50% inhibitory concentration) of 0.008 μM, had high in vitro potency against P. falciparum lines resistant to chloroquine (W2, IC = 0.0047 ± 0.0011 μM) and artemisinin (MRA1240, IC = 0.0086 ± 0.0010 μM). Excellent ex vivo potency of 6k was shown against clinical field isolates of both P. falciparum (IC = 0.022-0.034 μM) and Plasmodium vivax (IC = 0.0093-0.031 μM) from the blood of outpatients with uncomplicated malaria. Despite 6k being cleared relatively rapidly in mice, it suppressed parasitemia in the Peters 4-day test, with a mean ED value (50% effective dose) of 1.47 mg kg day following oral administration. The disubstituted triazine dimer 6k represents a new class of orally available antimalarial compounds of considerable interest for further development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.8b01799DOI Listing
March 2019

Evaluation of 4-Amino 2-Anilinoquinazolines against and Other Apicomplexan Parasites and in a Humanized NOD- IL2Rγ Mouse Model of Malaria.

Antimicrob Agents Chemother 2019 03 26;63(3). Epub 2019 Feb 26.

The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia

A series of 4-amino 2-anilinoquinazolines optimized for activity against the most lethal malaria parasite of humans, , was evaluated for activity against other human parasites and related apicomplexans that infect humans and animals. Four of the most promising compounds from the 4-amino 2-anilinoquinazoline series were equally as effective against the asexual blood stages of the zoonotic , suggesting that they could also be effective against the closely related , another important human pathogen. The 2-anilinoquinazoline compounds were also potent against an array of parasites resistant to clinically available antimalarial compounds, although slightly less so than against the drug-sensitive 3D7 parasite line. The apicomplexan parasites , , and were less sensitive to the 2-anilinoquinazoline series with a 50% effective concentration generally in the low micromolar range, suggesting that the yet to be discovered target of these compounds is absent or highly divergent in non- parasites. The 2-anilinoquinazoline compounds act as rapidly as chloroquine and when tested in rodents displayed a half-life that contributed to the compound's capacity to clear blood stages in a humanized mouse model. At a dose of 50 mg/kg of body weight, adverse effects to the humanized mice were noted, and evaluation against a panel of experimental high-risk off targets indicated some potential off-target activity. Further optimization of the 2-anilinoquinazoline antimalarial class will concentrate on improving efficacy and addressing adverse risk.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AAC.01804-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395901PMC
March 2019

SAR of a new antischistosomal urea carboxylic acid.

Bioorg Med Chem Lett 2018 12 25;28(23-24):3648-3651. Epub 2018 Oct 25.

College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, United States. Electronic address:

Urea carboxylic acids, products of aryl hydantoin hydrolysis, were recently identified as a new antischistosomal chemotype. We now describe a baseline structure-activity relationship (SAR) for this compound series. With one exception, analogs of lead urea carboxylic acid 2 were quite polar with Log D values ranging from -1.9 to 1.8, had high aqueous solubilities in the range of 25-100 µg/mL, and were metabolically stable. None of the compounds had measurable in vitro antischistosomal activity or cytotoxicity, but four of these had moderate worm burden reduction (WBR) values of 42-70% when they were administered as single 100 mg/kg oral doses to S. mansoni-infected mice. These data indicate that with the exception of the gem-dimethyl substructure and the distal nitrogen atom of the urea functional group, the rest of the structure of 2 is required for in vivo antischistosomal activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmcl.2018.10.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6301076PMC
December 2018

Inhibition of Cytomegalovirus Replication with Extended-Half-Life Synthetic Ozonides.

Antimicrob Agents Chemother 2019 01 21;63(1). Epub 2018 Dec 21.

Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

Artesunate (AS), a semisynthetic artemisinin approved for malaria therapy, inhibits human cytomegalovirus (HCMV) replication , but therapeutic success in humans has been variable. We hypothesized that the short half-life of AS may contribute to the different treatment outcomes. We tested novel synthetic ozonides with longer half-lives against HCMV and mouse cytomegalovirus (MCMV) Screening of the activities of four ozonides against a pp28-luciferase-expressing HCMV Towne recombinant identified OZ418 to have the best selectivity; its effective concentration inhibiting viral growth by 50% (EC) was 9.8 ± 0.2 µM, and cytotoxicity in noninfected human fibroblasts (the concentration inhibiting cell growth by 50% [CC]) was 128.1 ± 8.0 µM. In plaque reduction assays, OZ418 inhibited HCMV TB40 in a concentration-dependent manner as well as a ganciclovir (GCV)-resistant HCMV isolate. The combination of OZ418 and GCV was synergistic in HCMV inhibition Virus inhibition by OZ418 occurred at an early stage and was dependent on the cell density at the time of infection. OZ418 treatment reversed HCMV-mediated cell cycle progression and correlated with the reduction of HCMV-induced expression of pRb, E2F1, and cyclin-dependent kinases 1, 2, 4, and 6. In an MCMV model, once-daily oral administration of OZ418 had significantly improved efficacy against MCMV compared to that of twice-daily oral AS. A parallel pharmacokinetic study with a single oral dose of OZ418 or AS showed a prolonged plasma half-life and higher unbound concentrations of OZ418 than unbound concentrations of AS. In summary, ozonides are proposed to be potential therapeutics, alone or in combination with GCV, for HCMV infection in humans.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AAC.01735-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6325236PMC
January 2019

Using Human Plasma as an Assay Medium in Caco-2 Studies Improves Mass Balance for Lipophilic Compounds.

Pharm Res 2018 Sep 17;35(11):210. Epub 2018 Sep 17.

Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, VIC, 3052, Australia.

Purpose: To examine the utility of human plasma as an assay medium in Caco-2 permeability studies to overcome poor mass balance and inadequate sink conditions frequently encountered with lipophilic compounds.

Methods: Caco-2 permeability was assessed for reference compounds with known transport mechanisms using either pH 7.4 buffer or human plasma as the assay medium in both the apical and basolateral chambers. When using plasma, P values were corrected for the unbound fraction in the donor chamber. The utility of the approach was assessed by measuring the permeability of selected antimalarial compounds using the two assay media.

Results: Caco-2 cell monolayer integrity and P-gp transporter function were unaffected by the presence of human plasma in the donor and acceptor chambers. For many of the reference compounds having good mass balance with buffer as the medium, higher P values were observed with plasma, likely due to improved acceptor sink conditions. The lipophilic antimalarial compounds exhibited low mass balance with buffer, however the use of plasma markedly improved mass balance allowing the determination of more reliable P values.

Conclusions: The results support the utility of human plasma as an alternate Caco-2 assay medium to improve mass balance and permeability measurements for lipophilic compounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11095-018-2493-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6156755PMC
September 2018

Isoxazolopyrimidine-Based Inhibitors of Dihydroorotate Dehydrogenase with Antimalarial Activity.

ACS Omega 2018 Aug 15;3(8):9227-9240. Epub 2018 Aug 15.

Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, Texas 75390-9038, United States.

Malaria kills nearly 0.5 million people yearly and impacts the lives of those living in over 90 countries where it is endemic. The current treatment programs are threatened by increasing drug resistance. Dihydroorotate dehydrogenase (DHODH) is now clinically validated as a target for antimalarial drug discovery as a triazolopyrimidine class inhibitor () is currently undergoing clinical development. We discovered a related isoxazolopyrimidine series in a phenotypic screen, later determining that it targeted DHODH. To determine if the isoxazolopyrimidines could yield a drug candidate, we initiated hit-to-lead medicinal chemistry. Several potent analogues were identified, including a compound that showed in vivo antimalarial activity. The isoxazolopyrimidines were more rapidly metabolized than their triazolopyrimidine counterparts, and the pharmacokinetic data were not consistent with the goal of a single-dose treatment for malaria.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsomega.8b01573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120730PMC
August 2018