2-amido-3-(1H-indol-3-yl)-N-substituted-propanamides as a new class of falcipain-2 inhibitors. 1. Design, synthesis, biological evaluation and binding model studies

Molecules. 2009 Jan 21;14(1):494-508. doi: 10.3390/molecules14010494.


The Plasmodium falciparum cysteine protease falcipain-2 (FP-2) is an important cysteine protease and an essential hemoglobinase of erythrocytic P. falciparum trophozoites. The discovery of new FP-2 inhibitors is now a hot topic in the search for potential malaria treatments. In this study, a series of novel small molecule FP-2 inhibitors have been designed and synthesized based on three regional optimizations of the lead (R)-2-phenoxycarboxamido-3-(1H-indol-3-yl)-N-benzylpropanamide(1), which was identified using structure-based virtual screening in conjunction with surface plasmon resonance (SPR)-based binding assays. Four compounds--1, 2b, 2k and 2l--showed moderate FP-2 inhibition activity, with IC(50) values of 10.0-39.4 microM, and the inhibitory activity of compound 2k was approximately 3-fold better than that of the prototype compound 1 and may prove useful for the development of micromolar level FP-2 inhibitors. Preliminary SAR data was obtained, while molecular modeling revealed that introduction of H-bond donor or/and acceptor atoms to the phenyl ring moiety in the C region would be likely to produce some additional H-bond interactions, which should consequently enhance molecular bioactivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides* / chemical synthesis
  • Amides* / chemistry
  • Amides* / metabolism
  • Animals
  • Computer Simulation
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors* / chemistry
  • Cysteine Proteinase Inhibitors* / metabolism
  • Cysteine Proteinase Inhibitors* / therapeutic use
  • Drug Design
  • Humans
  • Malaria, Falciparum / drug therapy
  • Models, Molecular
  • Molecular Structure
  • Plasmodium falciparum / metabolism
  • Protein Conformation
  • Structure-Activity Relationship


  • Amides
  • Cysteine Proteinase Inhibitors
  • Cysteine Endopeptidases
  • falcipain 2