TY - JOUR
T1 - Identification via a Parallel Hit Progression Strategy of Improved Small Molecule Inhibitors of the Malaria Purine Uptake Transporter that Inhibit Plasmodium falciparum Parasite Proliferation
AU - Sosa, Yvett
AU - Deniskin, Roman
AU - Frame, I. J.
AU - Steiginga, Matthew S.
AU - Bandyopadhyay, Deepak
AU - Graybill, Todd L.
AU - Kallal, Lorena A.
AU - Ouellette, Michael T.
AU - Pope, Andrew J.
AU - Widdowson, Katherine L.
AU - Young, Robert J.
AU - Akabas, Myles H.
N1 - Funding Information:
We thank Dr. David Fidock (Columbia University) for the artemisinin-resistant Cam3.II parasite strain and for the HB3 and 7G8 strains. Vanessa Barroso-Poveda (GSK) performed the HepG2 cytotoxicity assays. This work was supported in part by a grant from the National Institutes of Health NIAID (RO1-AI116665 to M.H.A.) and by an unrestricted grant from GSK to M.H.A. to support work performed at the Albert Einstein College of Medicine. All work performed by GSK employees was supported by funds from GlaxoSmithKline. Y.S. was supported in part by training grant T32-AI070117 and by NIH NRSA individual fellowship F31-AI136488. R.D. and I.J.F. were supported in part by NIGMS Medical Scientist Training Grant T32-GM007288.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/5/7
Y1 - 2019/5/7
N2 - Emerging resistance to current antimalarial medicines underscores the importance of identifying new drug targets and novel compounds. Malaria parasites are purine auxotrophic and import purines via the Plasmodium falciparum equilibrative nucleoside transporter type 1 (PfENT1). We previously showed that PfENT1 inhibitors block parasite proliferation in culture. Our goal was to identify additional, possibly more optimal chemical starting points for a drug discovery campaign. We performed a high throughput screen (HTS) of GlaxoSmithKline's 1.8 million compound library with a yeast-based assay to identify PfENT1 inhibitors. We used a parallel progression strategy for hit validation and expansion, with an emphasis on chemical properties in addition to potency. In one arm, the most active hits were tested for human cell toxicity; 201 had minimal toxicity. The second arm, hit expansion, used a scaffold-based substructure search with the HTS hits as templates to identify over 2000 compounds; 123 compounds had activity. Of these 324 compounds, 175 compounds inhibited proliferation of P. falciparum parasite strain 3D7 with IC50 values between 0.8 and ∞180 μM. One hundred forty-two compounds inhibited PfENT1 knockout (pfent1Δ) parasite growth, indicating they also hit secondary targets. Thirty-two hits inhibited growth of 3D7 but not pfent1Δparasites. Thus, PfENT1 inhibition was sufficient to block parasite proliferation. Therefore, PfENT1 may be a viable target for antimalarial drug development. Six compounds with novel chemical scaffolds were extensively characterized in yeast-, parasite-, and human-erythrocyte-based assays. The inhibitors showed similar potencies against drug sensitive and resistant P. falciparum strains. They represent attractive starting points for development of novel antimalarial drugs.
AB - Emerging resistance to current antimalarial medicines underscores the importance of identifying new drug targets and novel compounds. Malaria parasites are purine auxotrophic and import purines via the Plasmodium falciparum equilibrative nucleoside transporter type 1 (PfENT1). We previously showed that PfENT1 inhibitors block parasite proliferation in culture. Our goal was to identify additional, possibly more optimal chemical starting points for a drug discovery campaign. We performed a high throughput screen (HTS) of GlaxoSmithKline's 1.8 million compound library with a yeast-based assay to identify PfENT1 inhibitors. We used a parallel progression strategy for hit validation and expansion, with an emphasis on chemical properties in addition to potency. In one arm, the most active hits were tested for human cell toxicity; 201 had minimal toxicity. The second arm, hit expansion, used a scaffold-based substructure search with the HTS hits as templates to identify over 2000 compounds; 123 compounds had activity. Of these 324 compounds, 175 compounds inhibited proliferation of P. falciparum parasite strain 3D7 with IC50 values between 0.8 and ∞180 μM. One hundred forty-two compounds inhibited PfENT1 knockout (pfent1Δ) parasite growth, indicating they also hit secondary targets. Thirty-two hits inhibited growth of 3D7 but not pfent1Δparasites. Thus, PfENT1 inhibition was sufficient to block parasite proliferation. Therefore, PfENT1 may be a viable target for antimalarial drug development. Six compounds with novel chemical scaffolds were extensively characterized in yeast-, parasite-, and human-erythrocyte-based assays. The inhibitors showed similar potencies against drug sensitive and resistant P. falciparum strains. They represent attractive starting points for development of novel antimalarial drugs.
KW - drug discovery
KW - high throughput screen
KW - malaria
KW - purine
KW - transporter
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U2 - 10.1021/acsinfecdis.9b00168
DO - 10.1021/acsinfecdis.9b00168
M3 - Article
C2 - 31373203
AN - SCOPUS:85071663557
VL - 5
SP - 1738
EP - 1753
JO - ACS Infectious Diseases
JF - ACS Infectious Diseases
SN - 2373-8227
IS - 10
ER -