Surugapyrone A from Streptomyces coelicoflavus strain USF-6280 as a new DPPH radical-scavenger.

Surugapyrone A, a novel 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging 2-pyrone, was isolated from the culture filtrate of an actinomycete strain USF-6280. This strain was assigned to the genus Streptomyces owing to its morphological and chemotaxonomic characteristics. Phylogenetic analysis based on 16S ribosomal RNA gene sequences supported the classification of the producing strain as a member of the genus Streptomyces and indicated that it was closely related to Streptomyces coelicoflavus. As the morphological, physiological and biochemical characteristics of the producing strain were in agreement with those of the type strain of S. coelicoflavus, we concluded that strain USF-6280 should be identified as a member of S. coelicoflavus. The structure of surugapyrone A was determined to be 4-hydroxy-6-isopropyl-3-methyl-2-pyrone on the basis of the spectroscopic data. The results of feeding experiments with (13)C-labeled compounds indicated that surugapyrone A was biosynthesized through a polyketide pathway involving isobutyrate, acetate and propionate.