Sphaerostilbellins, New Antimicrobial Aminolipopeptide Peptaibiotics from Sphaerostilbella toxica

Biomolecules. 2020 Sep 26;10(10):1371. doi: 10.3390/biom10101371.


Sphaerostilbella toxica is a mycoparasitic fungus that can be found parasitizing wood-decay basidiomycetes in the southern USA. Organic solvent extracts of fermented strains of S. toxica exhibited potent antimicrobial activity, including potent growth inhibition of human pathogenic yeasts Candida albicans and Cryptococcus neoformans, the respiratory pathogenic fungus Aspergillus fumigatus, and the Gram-positive bacterium Staphylococcus aureus. Bioassay-guided separations led to the purification and structure elucidation of new peptaibiotics designated as sphaerostilbellins A and B. Their structures were established mainly by analysis of NMR and HRMS data, verification of amino acid composition by Marfey's method, and by comparison with published data of known compounds. They incorporate intriguing structural features, including an N-terminal 2-methyl-3-oxo-tetradecanoyl (MOTDA) residue and a C-terminal putrescine residue. The minimal inhibitory concentrations for sphaerostilbellins A and B were measured as 2 μM each for C. neoformans, 1 μM each for A. fumigatus, and 4 and 2 μM, respectively, for C. albicans. Murine macrophage cells were unaffected at these concentrations.

Keywords: Hypocreaceae; antifungals; mycoparasite; nonribosomal peptide; putrescine; secondary metabolite.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemistry*
  • Anti-Bacterial Agents / pharmacology
  • Anti-Infective Agents / chemistry*
  • Anti-Infective Agents / pharmacology
  • Antifungal Agents / chemistry
  • Antifungal Agents / pharmacology*
  • Aspergillus fumigatus / drug effects
  • Aspergillus fumigatus / pathogenicity
  • Basidiomycota / chemistry*
  • Candida albicans / drug effects
  • Candida albicans / pathogenicity
  • Cryptococcus neoformans / drug effects
  • Cryptococcus neoformans / pathogenicity
  • Humans
  • Macrophages / drug effects
  • Mice
  • Microbial Sensitivity Tests
  • Staphylococcus aureus / pathogenicity


  • Anti-Bacterial Agents
  • Anti-Infective Agents
  • Antifungal Agents