Inhibitors of cyclic nucleotide phosphodiesterases produced by streptomyces. II. Isolation and structure of new isocoumarins.

Besides reticulol, the strain MD611-C6 produced two compounds which inhibited cyclic nucleotide phosphodiesterases [EC 3. 1. 4. C.] These substances were isolated and their structures were elucidated to be 8-hydroxy-6, 7-dimethoxy-3-hydroxymethylisocoumarin (II) and 6, 8-dihyroxy-7-methoxy-3-hydroxymethylisocoumarin (III). Concentrations of II and III for 50% inhibition of cAMP phosphodiesterase were 3.97×10-4M and 1.26×10-3M, respectively.