Biology subjects

Deni, I.

Publications and source records attributed to Deni, I..

4 recordsLinked to original sources

bioRxiv2025

Identification of α-azacyclic acetamide-based inhibitors of P. falciparum Na+ pump (PfATP4) with fast-killing asexual blood-stage antimalarial activity by phenotypic screening

Malaria treatments are compromised by drug resistance, creating an urgent need to discover new drugs. We used a phenotypic high-throughput screening (HTS) platform to identify new antimalarials, uncovering three related pyrrole-, indole-, and indoline-based series with a shared -azacyclic acetamide core. These compounds showed fast-killing activity on asexual blood-stage Plasmodium falciparum parasites, were not cytotoxic, and disrupted parasite intracellular pH and Na+ regulation similarly to cipargamin (KAE609), a clinically advanced inhibitor of the P. falciparum Na+ pump (PfATP4). PfATP4 is localized to the parasite plasma membrane and is essential for maintaining a low cytosolic Na+ concentration. Resistance selections on P. falciparum parasites with two -azacyclic acetamide analogs identified mutations in PfATP4, and cross-resistance was observed across the -azacyclic acetamides and KAE609, confirming PfATP4 as the target. PfATP4 is a well-established antimalarial target, and identification of additional PfATP4 inhibitors provides alternative avenues to disrupt its function.

microbiology↗

bioRxiv2024

A potent and selective reaction hijacking inhibitor of Plasmodium falciparum tyrosine tRNA synthetase exhibits single dose oral efficacy in vivo

The Plasmodium falciparum cytoplasmic tyrosine tRNA synthetase (PfTyrRS) is an attractive drug target that is susceptible to reaction-hijacking by AMP-mimicking nucleoside sulfamates. We previously identified an exemplar pyrazolopyrimidine ribose sulfamate, ML901, as a potent pro-inhibitor of PfTyrRS. Here we examined the stage specificity of action of ML901, showing very good activity against the schizont stage, but lower trophozoite stage activity. We explored a series of ML901 analogues and identified ML471, which exhibits improved potency against trophozoites and enhanced selectivity against a human cell line. Additionally, it has no inhibitory activity against human ubiquitin-activating enzyme (UAE) in vitro. ML471 exhibits low nanomolar activity against asexual blood stage P. falciparum and potent activity against liver stage parasites, gametocytes and transmissible gametes. It is fast-acting and exhibits a long in vivo half-life. ML471 is well-tolerated and shows single dose oral efficacy in the SCID mouse model of P. falciparum malaria. We confirm that ML471 is a pro-inhibitor that is converted into a tight binding Tyr-ML471 conjugate by the PfTyrRS enzyme. A crystal structure of the PfTyrRS/ Tyr-ML471 complex offers insights into improved potency, while molecular docking into UAE provides a rationale for improved selectivity.

biochemistry↗

bioRxiv2021

P. falciparum K13 mutations present varying degrees of artemisinin resistance and reduced fitness in African parasites

The emergence of artemisinin (ART) resistance in Plasmodium falciparum parasites, driven by K13 mutations, has led to widespread antimalarial treatment failure in Southeast Asia. In Africa, our genotyping of 3,299 isolates confirms the emergence of the K13 R561H variant in Rwanda and reveals the continuing dominance of wild-type K13 across 11 countries. We show that this mutation, along with M579I and C580Y, confers varying degrees of in vitro ART resistance in African parasites. C580Y and M579I cause substantial fitness costs, which may counter-select against their dissemination in high-transmission settings. We also define the impact of multiple K13 mutations on ART resistance and fitness in multiple Southeast Asian strains. ART susceptibility is unaltered upon editing point mutations in ferrodoxin or mdr2, earlier resistance markers. These data point to the lack of an evident biological barrier to mutant K13 mediating ART resistance in Africa, while identifying their detrimental impact on parasite growth.

physiology↗

bioRxiv2021

Plasmodium falciparum K13 mutations in Africa and Asia present varying degrees of artemisinin resistance and an elevated fitness cost in African parasites

The emergence of artemisinin (ART) resistance in Plasmodium falciparum parasites has led to increasing rates of treatment failure with first-line ART-based combination therapies (ACTs) in Southeast Asia. In this region, select mutations in K13 can result in delayed parasite clearance rates in vivo and enhanced survival in the ring-stage survival assay (RSA) in vitro. Our genotyping of 3,299 P. falciparum isolates across 11 sub-Saharan countries reveals the continuing dominance of wild-type K13 and confirms the emergence of a K13 R561H variant in Rwanda. Using gene editing, we provide definitive evidence that this mutation, along with M579I and C580Y, can confer variable degrees of in vitro ART resistance in African P. falciparum strains. C580Y and M579I were both associated with substantial fitness costs in African parasites, which may counter-select against their dissemination in high-transmission settings. We also report the impact of multiple K13 mutations, including the predominant variant C580Y, on RSA survival rates and fitness in multiple Southeast Asian strains. No change in ART susceptibility was observed upon editing point mutations in ferrodoxin or mdr2, earlier associated with ART resistance in Southeast Asia. These data point to the lack of an evident biological barrier to mutant K13 mediating ART resistance in Africa, while identifying their detrimental impact on parasite growth.

microbiology↗