Studies on bottromycins. I. 1H and 13C NMR assignments of bottromycin A2, the main component of the complex.

Bottromycins were first isolated from Streptomyces bottropensis by Waisvisz et al.1} and are especially active against Gram-positive bacteria and Mycoplasma1"3^.The complete structure of bottromycin A2 (1), the main active component of the complex, was first proposed by Nakamura et al. in 1966 as a linear peptide4'5), but the structure was revised in 1976 by Takahashi et al.6) to a partly cyclic structure by means of CI and El mass and *H and 13C NMR spectroscopy and chemical degradation studies.In 1983, Schipper7) reinvestigated the structure of 1 using *H and 15N NMR spectroscopy and re-revised it to the structure in which the chain moiety links to the cyclic moiety through the imino nitrogen of the amidine group as shown in Fig. 1.