FK409, a novel vasodilator isolated from the acid-treated fermentation broth of streptomyces griseosporeus. II. Structure of FK409 and its precursor FR-900411.

Abstract
In a purification study of novel vasodilator FK409 from the fermentation broth of Streptomyces griseosporeus, we found the existence of FR-900411, a precursor of FK-409 in the broth, suggesting that FK409 was derived from fR-900411 via a chemical reaction. We therefore isolated FR-900411 from the broth. The structure of FK409 and FR-900411 were determined to be 1 and 2 respectively, on the basis of spectroscopic and chemical evidence.