Induced production of depsipeptides by co-culturing Fusarium tricinctum and Fusarium begoniae

A co-culture of Fusarium tricinctum and Fusarium begoniae induced the production of two new linear depsipeptides, subenniatins A and B (1–2), which were not detected when either of the two fungi was cultured alone. The structures of the new compounds were unambiguously determined by analysis of 1D, 2D NMR, and mass spectra, as well as by chemical transformation. Complex NMR spectra were observed for compounds 1 and 2, which were attributed to the presence of rotamers as revealed by 1D NOE and ROESY measurements. Structurally, compounds 1 and 2 are biogenetic building blocks of the cytotoxic enniatins B, B1, A1, and A, which are the major metabolites of F. tricinctum when this fungus is cultured alone. Compounds 1 and 2 were found to be inactive in cytotoxic and antibacterial assays.