Characterization of the hepaene macrolide antibiotic produced by Streptomyces sp. FR-008

Streptomyces sp. FR-008 is a strain producing a complex of heptaene macrolide antifungal antibiotics, named FR-008, which was previously regarded to be similar to candicidin, but different in sugar moiety. The antibiotic FR-008 was extracted and separated from the cultured broth of Streptomyces sp. FR-008. A comparison between antibiotic FR-008 and candicidin has been made by studying the HPLC separation profiles of antibiotic FR-008, candicidin and a mixture of both. The retention time (RT) of each of the three main peaks of the antibiotic FR-008 is entirely identical to candicidin. The main component FR-008 was verified as candicidin D on the basis of ~(1)H-~(1)H NMR and ~(13)C-NMR studies. The possible structure of FR-008a could be proposed also after comparing the partial ~(1)H-NMR signals of the two compounds.