Epipolythiodiketopiperazine and trichothecene derivatives from the NaI-containing fermentation of marine-derived Trichoderma cf. brevicompactum

The marine-derived fungus Trichoderma sp. TPU199 (cf. Trichoderma brevicompactum ) produces pretrichodermamide A ( 1 ) and gliovirin ( 2 ), which possess a rare type of epipolythiodiketopiperazine (ETP) structure with a disulfide bridge between the α- and β-positions of two amino acid residues. We previously reported that this strain gave the halogenated ETPs, DC1149B ( 4 ), DC1149R ( 6 ), and iododithiobrevamide ( 7 ), when fermented with sodium halides (NaCl, NaBr, and NaI). Further analyses of the metabolites obtained under NaI-containing culture conditions resulted in the isolation of two new ETP derivatives ( 11 and 12 ) and three new trichothecene sesquiterpenes ( 13 – 15 ). The structures of 11 and 12 , including their absolute configurations, were elucidated based on spectroscopic data for 11 and 12 and comparisons with those for 1 and related compounds, revealing that 11 was an epimer of 1 at the C-5 position and 12 was a trithio-derivative of 11 . The structures of 13 – 15 were established by analyzing their 1D and 2D NMR data. The absolute configurations of 13 – 15 were assigned by comparing their experimental electronic circular dichroism (ECD) spectra with the calculated ECD spectrum of 13 .