Sordarin Diterpene Glycosides with an Unusual 1,3-Dioxolan-4-one Ring from the Zoanthid-Derived Fungus Curvularia hawaiiensis TA26-15

Six new sordarin tetracyclic diterpene glycosides, moriniafungins B-G (1-6), and a new sordaricin tetracyclic diterpene, sordaricin B (8), together with two known analogues, moriniafungin (7) and sordaricin (9), were isolated from the zoanthid-derived fungus Curvularia hawaiiensis TA26-15. The structures of the new compounds were elucidated by comprehensive analyses of spectroscopic data, including ID and 2D NMR and MS data. Compounds 1-6 represent the first case of sordarins from marine-derived fungi possessing a sordarose with a spiro 1,3-dioxolan-4-one ring, which is rare in the nature. Compound 4 showed antifungal activity against Candida albicans ATCC10231 with an MIC value of 2.9 mu M.