In Vitro Antitrypanosomal Activity of the Secondary Metabolites from the Mutant Strain IU-3 of the Insect Pathogenic Fungus Ophiocordyceps coccidiicola NBRC 100683

During the search for new antitrypanosomal drug leads, four antitrypanosomal compounds, of three depsipeptides and one nortriterpenoid, were isolated from cultures of the mutant strain IU-3 of the insect pathogenic fungus Ophiocordyceps coccidiicola NBRC 100683. Their structures were identified by the analysis of high resolution-electron ionization (HR-EI)-MS and HR-FAB-MS, and 1H- and 13C-NMR spectra, including extensive two dimensional (2D)-heteronuclear NMR experiments, and comparison with literature data for destruxin A (1), destruxin B (2), destruxin E chlorohydrin (3) and helvolic acid (4). Compounds 1–4 showed in vitro antitrypanosomal activity against Trypanosoma brucei brucei GUTat3.1 with IC50 values of 0.33, 0.16, 0.061 and 5.08 µg/mL, respectively.