Bioconversion of 6-epi-Notoamide T produces metabolites of unprecedented structures in a marine-derived Aspergillus sp.

We previously described the bioconversion of Notoamide T into (+)-Stephacidin A and (-)-Notoamide B, which suggested that Versicolamide B (8) is biosynthesized from 6-epi-Notoamide T (10) via 6-epi-Stephacidin A. Here we report that [C-13](2)-10 was incorporated into isotopically enriched 8 and seven new metabolites, which were not produced under normal culture conditions. The results suggest that the addition of excess precursor activated the expression of dormant tailoring genes giving rise to these structurally unprecedented metabolites. (C) 2014 Elsevier Ltd. All rights reserved.