Preparation and Ultraviolet Light-Induced Transformation of an Antifungal Mixture of Heptaene Antibiotics of Streptomyces surinam

Conditions for the production and isolation of an antifungal antibiotic mixture (DJ400) were investigated. Different preparations of DJ400 may contain at least 12 different heptaenes, which were characterized by partition chromatography (peak number) and ultraviolet (UV) spectra (types A, B, C). Irradiation with UV light transformed the predominant UV spectrum of type B into A. Comparison of untreated and UV-irradiated products indicated that the main components may exist in two forms with identical structures except for an all trans-heptaene system in A compounds and one internal cis double bond in B compounds. The ratio of the major components 6B and 8B depended on the media composition. Component 4B is probably a precursor of 6B; 10B and 12 may be precursors of 8B.