Iii and Iv Structural Studies

The production, isolation and characterization of rancinamycins I, II, III and IV have been described in a preceding communication." These metabolites, which exhibit in vitro activity against Gram-positive and Gram-negative bacteria, are produced by Streptomyces lincolnensis in media depleted of sulfur-containing inorganic or organic compounds. Rancinamycins I, II, III and IV behaved as single entities in several tlc and paper chromatographic systems. Gas chromatographic-mass spectroscopic analysis, however, revealed that each of rancinamycins I, II and III was a mixture of isomeric components". While each isomeric mixture was separated analytically the individual components have not been isolated. The studies reported in this communication, therefore, have been carried out on the isomeric mixtures. The present paper discusses the structure of the main components of the rancinamycin complex. Possible structures for the minor components and suggestions regarding the biosynthetic origin of rancinamycins are also discussed.