Frontiers in Cellular and Infection Microbiology (Nov 2022)

Targeting malaria parasites with novel derivatives of azithromycin

  • Amy L. Burns,
  • Amy L. Burns,
  • Brad E. Sleebs,
  • Brad E. Sleebs,
  • Maria Gancheva,
  • Kimberley T. McLean,
  • Ghizal Siddiqui,
  • Henrietta Venter,
  • James G. Beeson,
  • James G. Beeson,
  • James G. Beeson,
  • James G. Beeson,
  • Ryan O’Handley,
  • Ryan O’Handley,
  • Darren J. Creek,
  • Shutao Ma,
  • Sonja Frölich,
  • Christopher D. Goodman,
  • Geoffrey I. McFadden,
  • Danny W. Wilson,
  • Danny W. Wilson,
  • Danny W. Wilson

DOI
https://doi.org/10.3389/fcimb.2022.1063407
Journal volume & issue
Vol. 12

Abstract

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IntroductionThe spread of artemisinin resistant Plasmodium falciparum parasites is of global concern and highlights the need to identify new antimalarials for future treatments. Azithromycin, a macrolide antibiotic used clinically against malaria, kills parasites via two mechanisms: ‘delayed death’ by inhibiting the bacterium-like ribosomes of the apicoplast, and ‘quick-killing’ that kills rapidly across the entire blood stage development.MethodsHere, 22 azithromycin analogues were explored for delayed death and quick-killing activities against P. falciparum (the most virulent human malaria) and P. knowlesi (a monkey parasite that frequently infects humans).ResultsSeventeen analogues showed improved quick-killing against both Plasmodium species, with up to 38 to 20-fold higher potency over azithromycin after less than 48 or 28 hours of treatment for P. falciparum and P. knowlesi, respectively. Quick-killing analogues maintained activity throughout the blood stage lifecycle, including ring stages of P. falciparum parasites (<12 hrs treatment) and were >5-fold more selective against P. falciparum than human cells. Isopentenyl pyrophosphate supplemented parasites that lacked an apicoplast were equally sensitive to quick-killing analogues, confirming that the quick killing activity of these drugs was not directed at the apicoplast. Further, activity against the related apicoplast containing parasite Toxoplasma gondii and the gram-positive bacterium Streptococcus pneumoniae did not show improvement over azithromycin, highlighting the specific improvement in antimalarial quick-killing activity. Metabolomic profiling of parasites subjected to the most potent compound showed a build-up of non-haemoglobin derived peptides that was similar to chloroquine, while also exhibiting accumulation of haemoglobin-derived peptides that was absent for chloroquine treatment.DiscussionThe azithromycin analogues characterised in this study expand the structural diversity over previously reported quick-killing compounds and provide new starting points to develop azithromycin analogues with quick-killing antimalarial activity.

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