J Med Chem. 2014 Sep 11; 57(17): 7425–34.

Discovery of Carbohybrid-Based 2-Aminopyrimidine Analogues As a New Class of Rapid-Acting Antimalarial Agents Using Image-Based Cytological Profiling Assay.

Sukjun Lee,†,○ Donghyun Lim,‡,○ Eunyoung Lee, Nakyung Lee,§ Hong-gun Lee,|| Jonathan Cechetto,|| Michel Liuzzi, Lucio H. Freitas-Junior,§ Jin Sook Song, Myung Ae Bae, Sangmi Oh,#
Lawrence Ayong,*,† and Seung Bum Park*,‡,

Early Discovery Program, Institut Pasteur Korea, Seongnam-si, Gyeonggi-do 463-400, Korea

WCU Department of Biophysics and Chemical Biology, Seoul National University, San 56-1, Shilim-dong, Gwanak-gu, Seoul 151-747, Korea

§Center for Neglected Diseases Drug Discovery (CND3), Institut Pasteur Korea, Seongnam-si, Gyeonggi-do 463-400, Korea

||Center for Core Technologies, Institut Pasteur Korea, Seongnam-si, Gyeonggi-do 463-400, Korea

Drug Discovery Platform Technology Group, Drug Discovery Division, Korea Research Institute of Chemical Technology, Daejeon 305-600, Korea

#Medicinal Chemistry and Chemical Biology Group, Institut Pasteur Korea, Seongnam-si, Gyeonggi-do 463-400, Korea

Department of Chemistry, Seoul National University, Seoul 151-747, Korea

These authors contributed equally.

 

Abstract

New antimalarial agents that exhibit multistage 
activities against drug-resistant strains of malaria parasites 
represent good starting points for developing next-generation 
antimalarial therapies. To facilitate the progression of such 
agents into the development phase, we developed an image-
based parasitological screening method for defining drug
 effects on different asexual life cycle stages of Plasmodium 
falciparum. High-throughput screening of a newly assembled
 diversity-oriented synthetic library using this approach led to 
the identification of carbohybrid-based 2-aminopyrimidine
 compounds with fast-acting growth inhibitory activities against 
three laboratory strains of multidrug-resistant P. falciparum. Our structure−activity relationship study led to the identification of two derivatives (8aA and 11aA) as the most promising antimalarial candidates (mean EC50 of 0.130 and 0.096 μM against all three P. falciparum strains, selectivity indices >600, microsomal stabilities >80%, and mouse malaria ED50 values of 0.32 and 0.12 mg/kg/day, respectively), targeting all major blood stages of multidrug-resistant P. falciparum parasites.

 

Supplement:

  SBP FIG1  SBP FIG2

Figure 1. (A) Representative images of parasitized cultures showing P. falciparum major blood stages. (B) Antimalarial candidates 8aA and 11aA with excellent potency, high selectivity towards malaria parasites, and rapid acting activities against all major blood stages of P. falciparum.

 

Malaria is an infectious disease cause by Plasmodium species. With 0.6 million deaths and 200 million cases in 2013, the disease remains a serious public health problem particularly in the high transmission areas of Sub-Sahara Africa, Southeast Asia and Latin America. Unfortunately, it is difficult to control the disease due to the lack of vaccines and the propensity of malaria parasites to rapidly develop resistance against newly developed drugs. This dire situation calls for the development of novel antimalarial agents with fast-acting, long-lasting, and multistage activities.

We utilized an image-based high-content screening system for the quantitative detection of each major blood form (early rings, late rings, trophozoites, and schizonts) of P. falciparum parasites based on the numbers and sizes of detectable nuclear condensation spots which are identified using nuclear stain DAPI. In addition, the assay is capable of discriminating between viable and dead parasites in drug-treated samples by staining the functional mitochondria in live parasites. (Figure 1A).

To identify antimalarial compounds with novel modes of action, we screened an in-house small-molecule library using the image-based parasitological assay system and identified carbohybrid-based 2-aminopyrimidine analogues (8aA and 11aA) as the most promising candidates given their high excellent in vitro potency, high selectivity, and rapid acting activities against all asexual parasite forms. Furthermore, these compounds exhibited favorable pharmacokinetic properties and fast-acting in vivo efficacy. We conclude that these candidates can be a promising class of antimalarial agents with potentials for clinical use.

 

References

  1. World Health Organization, 2014, World malaria report 2014
  2. Moon S, Lee S, Kim H, Freitas-Junior LH, Kang M, Ayong L, Hansen MAE, 2013, An image analysis algorithm for malaria parasite stage classification and viability quantification. PLOS ONE 8:e61812

 

Acknowledgements

This work was supported by the Creative Research Initiative Grant (2014R1A3A2030423), the Bio & Medical Technology Development Program (2012M3A9C4048780), the Basic Research Laboratory (2010-0019766) funded by the National Research Foundation of Korea (NRF), the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP, no. 2007-00559), Gyeonggi-do, and KISTI. D.L. is grateful for a WCU-BK21 scholarship.

 

Contact:

Seung Bum Park, Ph. D.

Professor and Director

CRI Center for Chemical Proteomics

Department of Chemistry

Department of Biophysics and Chemical Biology

Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-747, Korea

sbpark@snu.ac.kr

http://hosting01.snu.ac.kr/~sbpark/

 

Lawrence Ayong, Ph. D.

Public Health and Epidemiology Unit

Centre Pasteur du Cameroun, P. O. Box 1274 Yaoundé, Cameroon

layong05@yahoo.co.uk

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