KS-504 compounds, novel inhibitors of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase from Mollisia ventosa.

Novel inhibitors of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase were isolated from the culture broth of a fungus, Mollisia ventosa KAC-1148. They were designated as KS-504a, KS-504b and KS-504d. A degradative product of KS-504a, called KS-504e, was also isolated and found to inhibit the enzyme. The 50% inhibitory concentration (IC50) values of KS-504a, KS-504b, KS-504d and KS-504e for bovine brain enzyme were 122, 109, greater than 500 and 139 microM, respectively.