In Vitro Efficacy of Free and Nanoparticle Formulations of Gallium(III) meso-Tetraphenylporphyrine against Mycobacterium avium and Mycobacterium abscessus and Gallium Biodistribution in Mice

Seoung Ryoung Choi, Bradley E. Britigan, Barbara Switzer, Traci Hoke, David Moran, Prabagaran Narayanasamy

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

The nontuberculous mycobacterial (NTM) pathogens, M. avium complex (MAC) and M. abscessus, can result in severe pulmonary infections. Current antibiotics confront significant challenges for treatment of these NTM infections due to emerging multidrug-resistance. Thus, development of new antibiotics targeted against these agents is needed. We examined the inhibitory activities of Ga(NO 3 ) 3 , GaCl 3 , gallium meso-tetraphenylporphyrine (GaTP), and gallium nanoparticles (GaNP) against intra- and extracellular M. avium and M. abscessus. GaTP, an analogue of natural heme, inhibited growth of both M. avium and M. abscessus with MICs in Fe-free 7H9 media of 0.5 and 2 μg/mL, respectively. GaTP was more active than Ga(NO 3 ) 3 and GaCl 3 . Ga(NO 3 ) 3 and GaCl 3 were not as active in Fe-rich media compared to Fe-free media. However, GaTP was much less impacted by exogenous Fe, with MICs against M. avium and M. abscessus of 2 and 4 μg/mL, respectively, in 7H9 OADC media (Fe rich). Confocal microscopy showed that GaNP penetrates the M. avium cell wall. As assessed by determining colony forming units, GaNP inhibited the growth of NTM growing in THP-1 macrophages up to 15 days after drug-loading of the cells, confirming a prolonged growth inhibitory activity of the GaNP. Biodistribution studies of GaNP conducted in mice showed that intraperitoneal injection is more effective than intramuscular injection in delivering Ga(III) into lung tissue. GaTP exhibits potential as a lead compound for development of anti-NTM agents that target heme-bound iron uptake mechanisms by mycobacteria and inhibit growth by disrupting mycobacterial iron acquisition/utilization.

Original languageEnglish (US)
Pages (from-to)1215-1225
Number of pages11
JournalMolecular Pharmaceutics
Volume15
Issue number3
DOIs
StatePublished - Mar 5 2018

Keywords

  • Mycobacterium abscessus
  • Mycobacterium avium
  • biodistribution
  • gallium nanoparticle
  • nontuberculous mycobacteria

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery

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