Identification and structural elucidation of new caprazamycins from Streptomyces sp. MK730-62F2 by liquid chromatography/electrospray ionization tandem mass spectrometry.

The development of reliable analytic methods, capable of separating mixtures of secondary metabolites as well as providing structural information, is essential for the investigation of secondary metabolites, e.g. from Streptomyces. Here we report a liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method using a triple quadrupole mass analyzer for the structural elucidation of caprazamycins and liposidomycins from culture extracts of the wild-type producer strains. Comparison of the fragmentation patterns in positive as well as in negative ionization mode revealed several characteristic product ions used for identification of six new caprazamycins. Furthermore, a chromatographic method for the purification of nucleosides from cell cultures using a boronic acid gel was adapted for the partial purification of the culture extracts.

Studies on novel bacterial translocase I inhibitors, A-500359s. I. Taxonomy, fermentation, isolation, physico-chemical properties and structure elucidation of A-500359 A, C, D and G.

In the course of our screening for bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (translocase I: EC 2.7.8.13) inhibitors, we found inhibitory activity in the cultured broth of the strain identified as Streptomyces griseus SANK 60196. The strain produced capuramycin and four novel capuramycin derivatives designated as A-500359 A, C, D and G. Purification and structural analysis were performed, and the structures of A-500359 A, C, D and G were elucidated as 6'''-methylcapuramycin, 3'-demethyl-6'''-methylcapuramycin, 2''-deoxy-6'''-methylcapuramycin and 3'-demethylcapuramycin, respectively.