Neocucurins A and B, two novel rearranged diterpenes from marine-derived fungus Neocucurbitaria unguis-hominis

Abstract

Neocucurins A (1) andB (2), were isolated from Neocucurbitaria unguis-hominis FS685. Neocucurin A was a diterpene with a unique 5/6/6/9 tetracyclic system, while neocucurins B featured the characteritic of bicyclo[8.3.1]tetradeca core skeleton, which was rearranged from the phomatin diterpene.Neocucurbitaria unguis-hominis Wanas., E.B.G. Jones & K.D. Hyde (basionym: Pyrenochaeta unguis-hominis Punith. & M.P. English) was first described in 1974 from a clinical isolation on human toe-nails by English & Atkinson. [1] Then, it was also found in human finger-nails and cornea to cause fungus infection. [2,3] In the present study, the strain N. unguis-hominis was isolated for the first time from a the deep-sea marine sediment sample. Secondary metabolisms from the genus Neocucurbitaria have been scarcely documented in the literature, with only a few of pyrones, 4-6 alkaloids, 7 and biphenyl compounds 7 . Recently, in the continuing research for structurally unique and biologically significant natural products from marine fungi, 8-12 the strain N. unguis-hominis FS685 was found in rich of novel phomactin diterpenes, which was the first report of this class of compounds in genus Neocucurbitaria. [13,14]