Tetronic acid derivatives from Aspergillus panamensis. Production, isolation, characterization and biological activity.

When Aspergillus panamensis, CBS 120.45, was grown on a medium with high carbon and low nitrogen content, it was found to produce six antibiotically active metabolites. All compounds were identified as tetronic acid derivatives; three of them were found to be identical with gregatins A, B, and D, previously reported as metabolites of Cephalosporium gregatum. The other three compounds are new. All six compounds show antibacterial activity towards Gram-negative and Gram-positive bacteria. Five of the antibiotics exhibit inhibitory effects on the macromolecular syntheses in cells of the ascitic form of EHRLICH carcinoma (ECA) of mice.