Exploring Heteroaromatic Rings as a Replacement for the Labile Amide of Antiplasmodial Pantothenamides

J Med Chem. 2021 Apr 22;64(8):4478-4497. doi: 10.1021/acs.jmedchem.0c01755. Epub 2021 Apr 1.

Abstract

Malaria-causing Plasmodium parasites are developing resistance to antimalarial drugs, providing the impetus for new antiplasmodials. Although pantothenamides show potent antiplasmodial activity, hydrolysis by pantetheinases/vanins present in blood rapidly inactivates them. We herein report the facile synthesis and biological activity of a small library of pantothenamide analogues in which the labile amide group is replaced with a heteroaromatic ring. Several of these analogues display nanomolar antiplasmodial activity against Plasmodium falciparum and/or Plasmodium knowlesi, and are stable in the presence of pantetheinase. Both a known triazole and a novel isoxazole derivative were further characterized and found to possess high selectivity indices, medium or high Caco-2 permeability, and medium or low microsomal clearance in vitro. Although they fail to suppress Plasmodium berghei proliferation in vivo, the pharmacokinetic and contact time data presented provide a benchmark for the compound profile likely required to achieve antiplasmodial activity in mice and should facilitate lead optimization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimalarials / chemistry*
  • Antimalarials / metabolism
  • Antimalarials / pharmacology
  • Antimalarials / therapeutic use
  • Caco-2 Cells
  • Cell Proliferation / drug effects
  • Drug Stability
  • Erythrocytes / cytology
  • Erythrocytes / parasitology
  • Female
  • Half-Life
  • Humans
  • Isoxazoles / chemistry*
  • Malaria, Falciparum / drug therapy
  • Mice
  • Mice, Inbred BALB C
  • Pantothenic Acid / analogs & derivatives*
  • Pantothenic Acid / chemistry
  • Pantothenic Acid / metabolism
  • Pantothenic Acid / pharmacology
  • Pantothenic Acid / therapeutic use
  • Plasmodium falciparum / drug effects
  • Plasmodium knowlesi / drug effects
  • Structure-Activity Relationship
  • Thiadiazoles / chemistry*
  • Triazoles / chemistry*

Substances

  • Antimalarials
  • Isoxazoles
  • Thiadiazoles
  • Triazoles
  • Pantothenic Acid
  • pantothenamide

Grants and funding