Isolation and chemical structure of aklanonic acid, an early intermediate in the biosynthesis of anthracyclines.

The fermentation, isolation and structure elucidation of aklanonic acid are described. The compound was isolated from fermentations of Streptomyces strain ZIMET 43,717. Aklanonic acid is a yellow-orange crystalline substance, melting at 203-204 degrees C (dec), having the molecular formula C21H16O8, and possessing UV maxima at 258, 282 (sh) and 438 nm (CHCl3). In dimethyl sulfoxide or pyridine aklanonic acid is unstable and a new compound (aklanone) is formed as a conversion product. The elucidation of the structures has shown that aklanonic acid and aklanone are derivatives of 1,8-dihydroxyanthraquinone.