Cytosporin Derivatives from Arctic-Derived Fungus Eutypella sp. D-1 via the OSMAC Approach.

A chemical investigation of the Arctic-derived fungus Eutypella sp. D-1 based on the OSMAC (one strain many compounds) approach resulted in the isolation of five cytosporin polyketides (compounds 1 - 3 and 11 - 12 ) from rice medium and eight cytosporins (compounds 2 and 4 - 11 ) from solid defined medium. The structures of the seven new compounds, eutypelleudesmane A ( 1 ), cytosporin Y ( 2 ), cytosporin Z ( 3 ), cytosporin Y 1 ( 4 ), cytosporin Y 2 ( 5 ), cytosporin Y 3 ( 6 ), and cytosporin E 1 ( 7 ), were elucidated by analyzing their detailed spectroscopic data. Structurally, cytosporin Y 1 ( 4 ) may be a key intermediate in the biosynthesis of the isolated cytosporins, rather than an end product. Compound 1 contained a unique skeleton formed by the ester linkage of two moieties, cytosporin F ( 12 ) and the eudesmane-type sesquiterpene dihydroalanto glycol. Additionally, the occurrence of cyclic carbonate moieties in compounds 6 and 7 was found to be rare in nature. The antibacterial, immunosuppressive, and cytotoxic activities of all compounds derived from Eutypella sp. D-1 were evaluated. Unfortunately, only compounds 3 , 6 , 8 , and 10 - 11 displayed immunosuppressive activity, with inhibitory rates of 62.9%, 59.5%, 67.8%, 55.8%, and 68.7%, respectively, at a concentration of 5 μg/mL.