Metabolic products of microorganisms. 261. Obscurolides, a novel class of phosphodiesterase inhibitors from streptomyces. I. Production, isolation, structural elucidation and biological activity of obscurolides A1 to A4.

Abstract

A novel class of butyrolactones, named obscurolides, was isolated from the culture nitrate of Streptomyces viridochromogenes by chemical screening methods. The structural elucidation of the obscurolides A₁ to A₄ (1 ~4) is described. The carboxy group of the 4-aminobenzoic acid moiety of obscurolide A₁ (1) is reduced in the other compounds. The isolated natural products have been proved to be diastereomeric mixtures by a partial racemization at C-7 which belongs to an allylic alcohol system. The obscurolides showed a weak inhibitory activity against calcium/calmodulin dependent and independent phosphodiesterases from bovine.