BIOCONVERSION OF ASCOMYCIN AND ITS 6-ALKOXYDERIVATIVES

Ascomycin is known to be O-demethylated to 32-O-desmethyl-ascomycin by bioconversion using the strain Actinoplanes sp. ATCC 53771. Using mod ified screening media, the conversion rate could be improved from prev iously published 15% to up to 35%. Together with 32-O-desmethyl-ascomy cin, two further metabolites, the already known 32-O-desmethyl-19-hydr oxymethylascomycin and the new 32-O-desmethyl-32-epi-ascomycin were is olated and characterized. Prompted by the observed demethylation capab ility of ATCC 53771, we studied whether this strain was also able to d ealkylate 6-alkoxy derivatives of ascomycin to 6-hydroxy-ascomycin. Al though the B-alkoxy derivatives were demethylated at various positions of the molecule, production of the hypothetical metabolite 6-hydroxy- ascomycin by biotransformation could not be shown. However, work up of the fermentation broth allowed the isolation and characterization of a new metabolite, the 6-ethoxy-15-desmethyl-ascomycin. (C) 1998 Elsevi er Science B.V. All rights reserved.