The Mass Spectra of the Lankacidin Antibiotics

Bundlins A and B, antibiotics elaborated by Streptomyces sp. 6642 GC₁, have the unique structures which possess a seventeen-membered carbon skeleton fused with an unusual β-keto-δ-Mactonic system and a pyruvamide side chain. In the course of the structural studies of the antibiotics, we found that these compounds showed the interesting fragmentations in their mass spectra and in consequence, the investigation about the interpretation of the principal peaks together with their formation mechanism was undertaken by the aid of high resolution mass spectrometry and the measurement of meta stable ions. In addition to the two antibiotics, the mass spectra of related compounds designated T–2636 D and T-2636 F were also investigated.