Broad-Spectrum Activity and Mechanisms of Action of SQ109 on a Variety of Fungi

Satish R. Malwal, Rocio Garcia-Rubio, Milena Kordalewska, Hoja Patterson, Chi Zhang, Jorge D. Calderin, Ruijie Zhou, Akanksha M. Pandey, Erika Shor, David S. Perlin, Nathan P. Wiederhold, Luis Ostrosky-Zeichner, Rutilio Fratti, Carol Nacy, Eric Oldfield

Research output: Contribution to journalArticlepeer-review

Abstract

We investigated the activity of the tuberculosis drug SQ109 against 16 fungal pathogens: Candida albicans, C. auris, C. glabrata, C. guilliermondi, C. kefyr, C. krusei, C. lusitaniae, C. parapsilosis, C. tropicalis, Cryptococcus neoformans, Rhizopus spp., Mucor spp., Fusarium spp., Coccidioides spp., Histoplasma capsulatum and Aspergillus fumigatus. MIC values varied widely (125 ng/mL to >64 μg/mL) but in many cases we found promising (MIC ∼ 4 μg/mL) activity as well as MFC/MIC ratios of ∼ 2. SQ109 metabolites were inactive. The activity of 12 analogs of SQ109 against Saccharomyces cerevisiae correlated with protonophore uncoupling activity, suggesting mitochondrial targeting, consistent with the observation that growth inhibition was rescued by agents which inhibit ROS species accumulation. SQ109 disrupted H+/Ca2+ homeostasis in S. cerevisiae vacuoles, and there was synergy (FICI ∼ 0.26) with pitavastatin, indicating involvement of isoprenoid biosynthesis pathway inhibition. SQ109 is, therefore, a potential antifungal agent with multitarget activity.

Original languageEnglish (US)
Pages (from-to)1662-1672
Number of pages11
JournalACS Infectious Diseases
Volume11
Issue number6
Early online dateMay 14 2025
DOIs
StatePublished - Jun 13 2025

Keywords

  • Candida
  • Histoplasma
  • antifungals
  • calcium
  • protonophore
  • vacuoles

ASJC Scopus subject areas

  • Infectious Diseases

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