In vitro and in vivo activity of a novel antifungal small molecule against Candida infections

PLoS One. 2014 Jan 22;9(1):e85836. doi: 10.1371/journal.pone.0085836. eCollection 2014.

Abstract

Candida is the most common fungal pathogen of humans worldwide and has become a major clinical problem because of the growing number of immunocompromised patients, who are susceptible to infection. Moreover, the number of available antifungals is limited, and antifungal-resistant Candida strains are emerging. New and effective antifungals are therefore urgently needed. Here, we discovered a small molecule with activity against Candida spp. both in vitro and in vivo. We screened a library of 50,240 small molecules for inhibitors of yeast-to-hypha transition, a major virulence attribute of Candida albicans. This screening identified 20 active compounds. Further examination of the in vitro antifungal and anti-biofilm properties of these compounds, using a range of Candida spp., led to the discovery of SM21, a highly potent antifungal molecule (minimum inhibitory concentration (MIC) 0.2-1.6 µg/ml). In vitro, SM21 was toxic to fungi but not to various human cell lines or bacterial species and was active against Candida isolates that are resistant to existing antifungal agents. Moreover, SM21 was relatively more effective against biofilms of Candida spp. than the current antifungal agents. In vivo, SM21 prevented the death of mice in a systemic candidiasis model and was also more effective than the common antifungal nystatin at reducing the extent of tongue lesions in a mouse model of oral candidiasis. Propidium iodide uptake assay showed that SM21 affected the integrity of the cell membrane. Taken together, our results indicate that SM21 has the potential to be developed as a novel antifungal agent for clinical use.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aniline Compounds / chemistry
  • Aniline Compounds / pharmacology
  • Animals
  • Antifungal Agents / chemistry
  • Antifungal Agents / pharmacology*
  • Candida albicans / drug effects*
  • Candida albicans / physiology
  • Candidiasis / microbiology
  • Candidiasis / prevention & control*
  • Cell Line
  • Cells, Cultured
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Drug Evaluation, Preclinical / methods
  • Fungal Proteins / genetics
  • Gene Expression / drug effects
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Host-Pathogen Interactions / drug effects
  • Humans
  • Male
  • Membrane Glycoproteins / genetics
  • Mice
  • Mice, Inbred C57BL
  • Microbial Sensitivity Tests
  • Microscopy, Confocal
  • Molecular Structure
  • Onium Compounds / chemistry
  • Onium Compounds / pharmacology
  • Promoter Regions, Genetic / genetics
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*

Substances

  • Aniline Compounds
  • Antifungal Agents
  • Fungal Proteins
  • HWP1 protein, Candida albicans
  • Membrane Glycoproteins
  • Onium Compounds
  • SM21 compound
  • Small Molecule Libraries
  • Green Fluorescent Proteins

Grant support

This study was funded by Health and Medical Research Fund, HKU Research Output Prize and HKU Small project funding to CJS and Tah-Wah Endowed Professorship fund to LPS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.