A NOVEL INOSITOL MONO-PHOSPHATASE INHIBITOR FROM Memnoniella echinata

PRODUCING ORGANISM, FERMENTATION, ISOLATION, PHYSICO-CHEMICAL AND IN VITRO BIOLOGICAL PROPERTIES

Abstract

A novel inositol mono-phosphatase inhibitor, L-671, 776 (1), was discovered from a culture of the hyphomycete, Memnoniella echinata (ATCC 20928). 1 has a molecular weight of 388 and a molecular formula of C₂₃H₃₂O₅. The mode of inhibition is non-competitive, with a Ki of 450μM. It shows no inhibition of myo-inositol 1, 4-bisphosphate 1-phosphatase or myo-inositol 1, 4, 5-triphosphate 5-phosphatase, although it weakly inhibits myo-inositol 1, 4, 5-triphosphate 3-kinase (IC₅₀ = 3 mM). It elevates inositol monophosphates in rat parotid slices (EC₅₀ approximately 3 mM), but abolishes agonist effects. It also produces short-lived contraction of guinea pig trachea at 300 μM.