Novel Inhibitors of Phosphatidylinositol 4-kinase IIIβ with Low Propensity for Resistance: Life Cycle Stage Activity and Efficacy in a Humanized Mouse Malaria Infection Model.

Anticancer ATP-competitive inhibitors are a promising source of new starting points for antimalarial drug discovery. Herein, we present a novel antimalarial chemotype based on the anticancer human ataxia-telangiectasia-mutated (ATM) kinase inhibitor AZD0156. This class inhibits phosphatidylinositol 4-kinase IIIβ (PI4K) in the human malaria parasite , demonstrating remarkable activities against all stages of the life cycle.

The Human Chk1 Inhibitor CHIR-124 Shows Multistage Activity Against via Dual Inhibition of Ark1 and Hemozoin Formation.

The high burden of malaria and growing resistance to frontline antimalarials demand new drugs with reduced propensities for generating resistance. An attractive approach to identifying chemical hits as starting points for antimalarial drug discovery involves the repositioning and chemical optimization of compounds used in other disease areas that are active against the human malaria parasite . Here we show that the human checkpoint kinase 1 (Chk1) inhibitor CHIR-124 is active against both drug-sensitive and drug-resistant asexual blood stage parasites and competitively binds to several kinases, including aurora-related kinase-1 (Ark1).

Ferrocenyl Quinoline-Benzimidazole Hybrids: A Multistage Strategy to Combat Drug-Resistant Malaria.

Molecular hybridization and metal incorporation are widely employed strategies for drug development aimed at enhancing pharmacological efficacy while mitigating the emergence of drug resistance. The effectiveness of these approaches is supported by numerous studies demonstrating their success against a range of diseases. Despite the deployment of malaria vaccines, effective treatment remains hindered by the persistent emergence of drug-resistant strains, contributing to an alarming global disease burden.

Characterizing the quick-killing mechanism of action of azithromycin analogs against malaria parasites.

Drug resistance is steadily undermining the efficacy of frontline anti-malarials, highlighting the urgent need for novel therapies with alternative mechanisms of action. The chemical addition of different moieties to azithromycin yields compounds with improved quick-killing potency against malaria parasites, with the most active analogs typically containing a chloroquinoline group. Here, we investigated the quick-killing mechanism of five azithromycin analogs, two of which contain differentially oriented chloroquinoline moieties.

Medicinal Chemistry Progression of Sapanisertib, the Anticancer and Dual Phosphatidylinositol 4-Kinase Beta and cGMP-Dependent Protein Kinase Inhibitor, for Malaria.

We recently demonstrated that the anticancer human mTOR inhibitor sapanisertib displays antimalarial activity in a malaria mouse model of infection and inhibits multiple kinases, including the high-value targets phosphatidylinositol 4-kinase type III beta (PI4Kβ) and cGMP-dependent protein kinase (PKG). Herein, we explore structure-activity relationships for sapanisertib analogues with benzyl and pyridyl substituents at the 7-position of the pyrazolopyrimidine core. New analogues with improved safety profiles were identified, including analogues with dual PI4Kβ and PKG inhibitory activity (exemplified by ), as well as potent PI4Kβ inhibitors with minimal inhibitory activity against PKG (exemplified by ).

The ATM Kinase Inhibitor AZD0156 Is a Potent Inhibitor of Plasmodium Phosphatidylinositol 4-Kinase (PI4Kβ) and Is an Attractive Candidate for Medicinal Chemistry Optimization Against Malaria.

New compounds targeting human malaria parasites are critical for effective malaria control and elimination. Here, we pursued the imidazoquinolinone AZD0156 (MMV1580483), a human ataxia-telangiectasia mutated (ATM) kinase inhibitor that completed Phase I clinical trials as an anticancer agent. We validated its in vitro activity against the two main forms of the Plasmodium falciparum parasite in the human host, viz.

Inhibitors of malaria parasite cyclic nucleotide phosphodiesterases block asexual blood-stage development and mosquito transmission.

Cyclic nucleotide-dependent phosphodiesterases (PDEs) play essential roles in regulating the malaria parasite life cycle, suggesting that they may be promising antimalarial drug targets. PDE inhibitors are used safely to treat a range of noninfectious human disorders. Here, we report three subseries of fast-acting and potent PDEβ inhibitors that block asexual blood-stage parasite development and that are also active against human clinical isolates.

Eliminating malaria transmission requires targeting immature and mature gametocytes through lipoidal uptake of antimalarials.

Novel antimalarial compounds targeting both the pathogenic and transmissible stages of the human malaria parasite, Plasmodium falciparum, would greatly benefit malaria elimination strategies. However, most compounds affecting asexual blood stage parasites show severely reduced activity against gametocytes. The impact of this activity loss on a compound's transmission-blocking activity is unclear.

The Tuberculosis Drug Candidate SQ109 and Its Analogs Have Multistage Activity against .

Toward repositioning the antitubercular clinical candidate SQ109 as an antimalarial, analogs were investigated for structure-activity relationships for activity against asexual blood stages of the human malaria parasite pathogenic forms, as well as transmissible, sexual stage gametocytes. We show that equipotent activity (IC) in the 100-300 nM range could be attained for both asexual and sexual stages, with the activity of most compounds retained against a multidrug-resistant strain. The multistage activity profile relies on high lipophilicity ascribed to the adamantane headgroup, and antiplasmodial activity is critically dependent on the diamine linker.

2,8-Disubstituted-1,5-naphthyridines as Dual Inhibitors of Phosphatidylinositol-4-kinase and Hemozoin Formation with Efficacy.

Structure-activity relationship studies of 2,8-disubstituted-1,5-naphthyridines, previously reported as potent inhibitors of () phosphatidylinositol-4-kinase β (PI4K), identified 1,5-naphthyridines with basic groups at 8-position, which retained PI4K inhibitory activity but switched primary mode of action to the host hemoglobin degradation pathway through inhibition of hemozoin formation. These compounds showed minimal off-target inhibitory activity against the human phosphoinositide kinases and MINK1 and MAP4K kinases, which were associated with the teratogenicity and testicular toxicity observed in rats for the PI4K inhibitor clinical candidate MMV390048. A representative compound from the series retained activity against field isolates and lab-raised drug-resistant strains of .

Exploring the modulatory influence on the antimalarial activity of amodiaquine using scaffold hybridisation with ferrocene integration.

Amodiaquine (AQ) is a potent antimalarial drug used in combination with artesunate as part of artemisinin-based combination therapies (ACTs) for malarial treatment. Due to the rising emergence of resistant malaria parasites, some of which have been reported for ACT, the usefulness of AQ as an efficacious therapeutic drug is threatened. Employing the organometallic hybridisation approach, which has been shown to restore the antimalarial activity of chloroquine in the form of an organometallic hybrid clinical candidate ferroquine (FQ), the present study utilises this strategy to modulate the biological performance of AQ by incorporating ferrocene.

Novel 3-Trifluoromethyl-1,2,4-oxadiazole Analogues of Astemizole with Multi-stage Antiplasmodium Activity and Efficacy in a Mouse Malaria Infection Model.

Iterative medicinal chemistry optimization of an ester-containing astemizole (AST) analogue with an associated metabolic instability liability led to the identification of a highly potent 3-trifluoromethyl-1,2,4-oxadiazole analogue (NF54 IC = 0.012 μM; K1 IC = 0.040 μM) displaying high microsomal metabolic stability (HLM CL < 11.

New Transmission-Selective Antimalarial Agents through Hit-to-Lead Optimization of 2-([1,1'-Biphenyl]-4-carboxamido)benzoic Acid Derivatives.

Malaria elimination requires multipronged approaches, including the application of antimalarial drugs able to block human-to-mosquito transmission of malaria parasites. The transmissible gametocytes of Plasmodium falciparum seem to be highly sensitive towards epidrugs, particularly those targeting demethylation of histone post-translational marks. Here, we report exploration of compounds from a chemical library generated during hit-to-lead optimization of inhibitors of the human histone lysine demethylase, KDM4B.

In vitro dual activity of Aloe marlothii roots and its chemical constituents against Plasmodium falciparum asexual and sexual stage parasites.

Ethnopharmacological Relevance: Aloe marlothii A.Berger (Xanthorrhoeaceae) is indigenous to southern African countries where its aqueous preparations are used in traditional medicine to treat several ailments including hypertension, respiratory infections, venereal diseases, chest pain, sore throat and malaria.

Aim Of The Study: The aims of this study were as follows: (i) isolate and identify the antiplasmodial active compounds in A.

Streamlined and Robust Stage-Specific Profiling of Gametocytocidal Compounds Against .

Malaria elimination is dependent on the ability to target both the pathogenic and transmissible stages of the human malaria parasite, . These forms of the parasite are differentiated by unique developmental stages, each with their own biological mechanisms and processes. These individual stages therefore also respond differently to inhibitory compounds, and this complicates the discovery of multistage active antimalarial agents.

Adapt or Die: Targeting Unique Transmission-Stage Biology for Malaria Elimination.

parasites have a complex life cycle that includes development in the human host as well as the vector. Successful transmission of the parasite between its host and vector therefore requires the parasite to balance its investments in asexual replication and sexual reproduction, varying the frequency of sexual commitment to persist within the human host and generate future opportunities for transmission. The transmission window is extended further by the ability of stage V gametocytes to circulate in peripheral blood for weeks, whereas immature stage I to IV gametocytes sequester in the bone marrow and spleen until final maturation.

Semi-Synthetic Analogues of Cryptolepine as a Potential Source of Sustainable Drugs for the Treatment of Malaria, Human African Trypanosomiasis, and Cancer.

The prospect of eradicating malaria continues to be challenging in the face of increasing parasite resistance to antimalarial drugs so that novel antimalarials active against asexual, sexual, and liver-stage malaria parasites are urgently needed. In addition, new antimalarials need to be affordable and available to those most in need and, bearing in mind climate change, should ideally be sustainable. The West African climbing shrub is used traditionally for the treatment of malaria; its principal alkaloid, cryptolepine (), has been shown to have antimalarial properties, and the synthetic analogue 2,7-dibromocryptolepine () is of interest as a lead toward new antimalarial agents.

Adsorption to the Surface of Hemozoin Crystals: Structure-Based Design and Synthesis of Amino-Phenoxazine β-Hematin Inhibitors.

In silico adsorption of eight antimalarials that inhibit β-hematin (synthetic hemozoin) formation identified a primary binding site on the (001) face, which accommodates inhibitors via formation of predominantly π-π interactions. A good correlation (r =0.64, P=0.

The ecdysone receptor regulates several key physiological factors in Anopheles funestus.

Background: Malaria is a devastating disease, transmitted by female Anopheles mosquitoes infected with Plasmodium parasites. Current insecticide-based strategies exist to control the spread of malaria by targeting vectors. However, the increase in insecticide resistance in vector populations hinder the efficacy of these methods.

A Dynamic and Combinatorial Histone Code Drives Malaria Parasite Asexual and Sexual Development.

Histone posttranslational modifications (PTMs) frequently co-occur on the same chromatin domains or even in the same molecule. It is now established that these "histone codes" are the result of cross talk between enzymes that catalyze multiple PTMs with univocal readout as compared with these PTMs in isolation. Here, we performed a comprehensive identification and quantification of histone codes of the malaria parasite, Plasmodium falciparum.

The Artemiside-Artemisox-Artemisone-M1 Tetrad: Efficacies against Blood Stage Parasites, DMPK Properties, and the Case for Artemiside.

Because of the need to replace the current clinical artemisinins in artemisinin combination therapies, we are evaluating fitness of amino-artemisinins for this purpose. These include the thiomorpholine derivative artemiside obtained in one scalable synthetic step from dihydroartemisinin (DHA) and the derived sulfone artemisone. We have recently shown that artemiside undergoes facile metabolism via the sulfoxide artemisox into artemisone and thence into the unsaturated metabolite M1; DHA is not a metabolite.

Chemogenomic Fingerprints Associated with Stage-Specific Gametocytocidal Compound Action against Human Malaria Parasites.

Kinase-focused inhibitors previously revealed compounds with differential activity against different stages of gametocytes. MMV666810, a 2-aminopyrazine, is more active on late-stage gametocytes, while a pyrazolopyridine, MMV674850, preferentially targets early-stage gametocytes. Here, we probe the biological mechanisms underpinning this differential stage-specific killing using in-depth transcriptome fingerprinting.

Structure-Activity Relationship Studies Reveal New Astemizole Analogues Active against In Vitro.

In the context of drug repositioning and expanding the existing structure-activity relationship around astemizole (AST), a new series of analogues were designed, synthesized, and evaluated for their antiplasmodium activity. Among 46 analogues tested, compounds , , and displayed high activities against asexual blood stage parasites (NF54 IC = 0.025-0.

Antimalarial Benzimidazole Derivatives Incorporating Phenolic Mannich Base Side Chains Inhibit Microtubule and Hemozoin Formation: Structure-Activity Relationship and Oral Efficacy Studies.

A novel series of antimalarial benzimidazole derivatives incorporating phenolic Mannich base side chains at the C2 position, which possess dual asexual blood and sexual stage activities, is presented. Structure-activity relationship studies revealed that the 1-benzylbenzimidazole analogues possessed submicromolar asexual blood and sexual stage activities in contrast to the 1-benzimidazole analogues, which were only active against asexual blood stage (ABS) parasites. Further, the former demonstrated microtubule inhibitory activity in ABS parasites but more significantly in stage II/III gametocytes.