Studies on SF=1902 A2 A5, minor components of SF-1902 (globomycin).

Four members of globomycin, SF-1902 A2, A3, A4a and A4b were newly isolated from the culture of Streptomyces hygroscopicus SF-1902. These minor components shared four amino acids in common and the fifth was either valine or allo-isoleucine. The fatty acid moiety varied from 3-hydroxy-2-methylheptanoic acid in A2 to 3-hydroxy-2-methylundecanoic acids in A4b. The length of alkyl chain greatly affected the antibacterial activity, and maximum activity was shown by the homologue (A5) possessing the longest alkyl chain.