SF2809 compounds, novel chymase inhibitors from Dactylosporangium sp. 2. Structural elucidation.

Novel chymase inhibitors, SF2809-I, II, III, IV, V and VI, were isolated from the fermentation broth of Dactylosporangium sp. SF2809, and their structures were determined by spectroscopic analyses. SF2809 compounds commonly contain a substituted indole moiety and a quinolinone moiety. The two moieties are connected to a methylene carbon in SF2809-I and III. The other compounds, SF2809-II, IV, V and VI, have an additional moiety, a p-hydroxyphenyl group or a phenyl group. In these compounds, all of three moieties are connected to a methine carbon. Furthermore, studies concerning the stereochemistry of SF2809-V revealed that the isolated compound was racemic, and the isomer possessing (R)-configuration was about thirty times more potent than another isomer.