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Detailed studies on the 13C and 1H NMR spectra of chromomycins A2 and A3, olivomycins A and B, and their derivatives clarified the assignment of many signals which had been unassigned or erroneously reported in the literatures. The revised assignments for chromomycin A3 and olivomycin A include the assignment of a key 13C signal used to discuss the saccharide linkage in question. Structure analyses based on the revised assignments support the alpha,1----3-bond between components of the disaccharide moiety in the molecules. Some general information useful for structure analysis of saccharides is also reported.

Thiocillins I, II and III were compared with micrococcin P1 by analysis of acid hydrolyzates of the native and the reduced antibiotics as well as by means of 1H and 13CNMR spectroscopies. As a result of these studies, the differences of these antibiotics were clarified in their structural units, and the structures of thiocillins I, II and III were assigned on the basis of the proposed structure of micrococcin P1.

The peptide antibiotic siomycin-A was transformed into half-esters with dicarboxylic acids with the intention of making siomycin-A soluble in water. Sodium salts of the half-esters were also prepared. Some of the salts showed antibacterial activities comparable to siomycin-A against Gram-positive bacteria in vitro and exhibited better therapeutic effects in infected mice than siomycin-A. The chemical structures of siomycin-A hemiadipate-II and -III were elucidated by comparing their 13C and 1H NMR spectra with those of siomycin-A. Their physicochemical properties are described.