Isolation of 8'-phosphate ester derivatives of amicoumacins: structure-activity relationship of hydroxy amino acid moiety.

Two new compounds, 8'-phospho derivatives of amicoumacins A and B, were isolated from the culture broth of a strain of Bacillus pumilus together with amicoumacins A and B. Their structures were elucidated on the basis of spectroscopic methods and alkaline phosphatase treatments. Comparison of the antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA) of these compounds suggested that C-8' hydroxyl and C-12' amide group of amicoumacin A played a critical role for anti-MRSA activity.