Three new members of the fluostatin family, fluostatins CϳE, were discovered in a culture filtrate extract of strain Acta 1383 during an HPLC screening program. The producing strain belongs to the genus Streptomyces and is closely related to type strains classified in the Streptomyces lavendulae 16S rRNA subclade. Fluostatins are named by their characteristic fluorenone chromophore. Fluostatin C shows moderate activity against selected human tumor cell lines.

Three new fluostatin antibiotics have been isolated from the culture filtrate of Streptomyces strain Acta 1383. The chemical structures of these compounds were determined by mass spectrometry and NMR spectroscopy. The relative configuration has been determined by X-ray crystal structure analysis and the absolute configuration was deduced from NMR data with the help of Helmchen esters. These compounds represent the first reported epoxide fluostatins (1, 2) and underline previously found analogies to the group of kinamycin antibiotics.