Moiramide A

Andrimid (I) and moiramides A-C were isolated from solid agar cultures of a marine isolate of P. fluorescens.The chem. structures of moiramides A-C were elucidated by anal. of spectroscopic data.I and moiramide B (II) exhibited potent in vitro inhibition of methicillin-resistant Staphylococcus aureus.Stable isotope incorporation experiments were used to elucidate the biogenesis of the acylsuccinimide fragment of I that is essential for antimicrobial activity.These experiments demonstrated that the acylsuccinimide fragment is derived from a combination of acetate and amino acid building blocks.It has been proposed that the biosynthesis proceeds through a dipeptide-like intermediate formed from γ-amino-β-keto acids that are in turn formed from valine and glycine homologated with acetate, presumably via malonyl-CoA.