Novobiocin and Coumermycin A1

Abstract

Coumermycin A1 was the most active of at least five antimicrobial agents produced by Streptomyces species isolated from soil samples in Hokkaido, Japan (Streptomyces rishiriensis) as well as in Gaspé, Canada (Streptomyces hazeliensis ; Berger etal., 1965a; Kawaguchi etal., 1965a). A mutant of S. rishiriensis was isolated that produced only two compounds, coumermycin A1 and coumermycin A2. The latter, which was up to 80 times less active than coumermycin A1 against some Staphylococcus aureus strains (Kawaguchi et al., 1965b, c; Cron et al., 1970), was not produced if the culture medium was supplemented with 0.01 μg/ml cobalt (Claridge et al., 1966). Determination of the structures of coumermycins A1 and A2 (Berger et al., 1965; Kawaguchi et al., 1965a, b, c) revealed that they only differed in that coumermycin A2 lacked the methyl group present at the five position of each terminal pyrrole group (Fig. 1).