Acremonidins, new polyketide-derived antibiotics produced by Acremonium sp., LL-Cyan 416.

Acremonidins A to approximately E (1 to approximately 5) were produced by fermentation of Acremonium sp., LL-Cyan 416, in heterogeneous phases. The structures of these compounds, containing a bridging keto group, were determined by spectroscopic analysis. Acremonidins A and B showed moderate activity against Gram-positive bacteria, including the methicillin-resistant staphylococci and vancomycin-resistant enterococci. Selective acylations of acremonidin B afforded ester derivatives 6 to approximately 9 that exhibited improved antibacterial activity.