STUDIES ON ANTIBIOTIC SF-837, A NEW ANTIBIOTIC

IV. STRUCTURES OF ANTIBIOTICS SF-837 A₂, A₃ AND A₄

Abstract

The present paper presents evidence as to the structures of antibiotics SF-837 A₂, A₃ and A₄, minor components of an antibiotic mixture produced by Streptomyces mycarofaciens. Mass spectrometry of three new macrolides, antibiotics SF-837 A₂, A₃ and A₄, revealed that each is composed of the elements of mycaminose, an O-acyl mycarose and an O-acyl macrocyclic lactone. Microbiological deacylation was employed to correlate antibiotic SF-837 A₂ with the parent SF-837. Manganese dioxide oxidation of antibiotics SF-837 and SF-837 A₂ yielded compounds identical with SF-837 A₃ and A₄, respectively. These transformations define the structure and stereochemistry of the three minor components of the SF-837 antibiotic mixture.