FK409, A NOVEL VASODILATOR ISOLATED FROM THE ACID-TREATED FERMENTATION BROTH OF STREPTOMYCES GRISEOSPOREUS

I. TAXONOMY, FERMENTATION, ISOLATION, AND PHYSICO-CHEMICAL AND BIOLOGICAL CHARACTERISTICS

Abstract

FK409, a novel vasodilator with anti-platelet aggregation activity, has been isolated from the acid-treated fermentation broth of Streptomyces griseosporeus No. 16917, which was cultured on a medium containing NaNO₃ for 4 days. FK409 was purified from the culture-filtrate by extraction with ethyl acetate after adjusting the pH to 3.0 with HCl, followed by silica gel chromatography. The molecular formula of this compound was determined to be C₈H₁₃N₃O₄.
In vitro, FK409 showed a potent relaxation activity on noradrenaline induced contraction of rat aorta. In addition to the vasodilating activity, this compound also showed potent anti-aggregation activities towards rabbit platelets. In vivo, intravenously administered FK409 resulted in marked blood pressure lowering in rats.