The Leupyrrins:  A Structurally Unique Family of Secondary Metabolites from the Myxobacterium Sorangium cellulosum^#

The structurally unique leupyrrins A₁ (1), A₂ (2), B₁ (3), B₂ (4), C (5), and D (6) were isolated as one of three groups of secondary metabolites from Sorangium cellulosum strains So ce705 and So ce690. An unusually substituted γ-butyrolactone ring and pyrrole and oxazoline rings are embedded in a nonsymmetric macrodiolide core structure, giving rise to compounds 1−6 as members of a novel class of secondary metabolites. Leupyrrin A₁ (1) shows good biological activity against various fungi and eukaryotic cells.