Isolation and structures of novel fungal depsidones, emeguisins A, B, and C, from Emericella unguis

Abstract

Three novel depsidones designated emeguisins A (1), C₂₃H₂₃ClO₅, B (2), C₂₄H₂₅ClO₅, and C (3), C₂₄H₂₄Cl₂O₅, were isolated from the mycelium of Emericella unguis, strain IFM 42017. Their structures were determined on the basis of spectroscopic and chemical investigations of these compounds and their derivatives. This is the first example of depsidones bearing two 1-methylprop-1-enyl groups in one molecule having been isolated. It is also interesting to note that 3-ethyl-5,7-dihydroxy-3,6-dimethylphthalide (7) was isolated from the same fungus, in view of the probable biogenesis of the above three depsidones.