Cephabacins, new cephem antibiotics of bacterial origin. III. Structural determination.

The structures of 15 new cephem antibiotics, cephabacin F1-9 and H1-6, were determined by their spectroscopic analyses and decomposition studies. They are consisted of a cephalosporin nucleus and a di, tri or tetrapeptide including a new amino acid which is bound at the position 3 with an ester bond. The components, F1-9, showed unique biological activities by the presence of a formylamino group at the position 7.