Fusagerins A-F, New Alkaloids from the Fungus Fusarium sp.

Fusagerins A-F (1-6), six new alkaloids including a unique one with the rare a-(N-formyl)carboxamide moiety (1), a hydantoin (imidazolidin-2,4-dione) derivative (2), and four fungerin analogues (3-6), were isolated from the crude extract of the fungus Fusarium sp., together with the known compound fungerin (7). Compound 2 was isolated as a racemate and further separated into two enantiomers on a chiral HPLC column. The structures of 1-6 were determined mainly by NMR experiments, and the absolute configuration of 1 and 2 was assigned by electronic circular dichroism (ECD) calculations. Compound 7 showed antibacterial activity against Staphylococcus aureus and Streptococcus pneumoniae, and weak cytotoxicity against the T24 cells.