Structures of BAY o 6997 and BAY q 1313 microbial ACE inhibitors

BAY o 6997 and BAY q 1313 are two novel ACE inhibitors produced by Streptomyces WS 464 and Streptomyces WS 1065, respectively. Their structures were elucidated by NMR and MS analysis of the inhibitors and a substance which formed on decomposition of BAY o 6997 on heating in 4 M acetic acid. Both inhibitors are composed of the same amino acids, namely His and 2-methylamino-4-aminobutyric acid. The 2-amino group of His and the 4-amino group of the 2-methylamino-4-aminobutyric acid are bridged by differently substituted ethylene moieties. As determined by gas chromatography on a chiral phase, both amino acids isolated from the total hydrolysate after derivatisation, at least in BAY o 6997, possess the L-configuration.