Two New Diketomorpholine Derivatives and a New Highly Conjugated Ergostane-Type Steroid from the Marine Algal-Derived Endophytic Fungus Aspergillus alabamensis EN-547

摘要

Chemical investigation of the marine algal-derived endophytic fungus Aspergillus alabamensis EN-547 resulted in the isolation of 4- epi - seco -shornephine A methyl ester ( 1 ) and 4- epi - seco -shornephine A carboxylic acid ( 2 ), two new secondary metabolites having a rare diketomorpholine motif, and 28-acetoxy-12 β ,15 α ,25-trihydroxyergosta-4,6,8(14),22-tetraen-3-one ( 3 ), a new highly conjugated ergostane-type steroid, together with four known metabolites ( 4 – 7 ). Their chemical structures were elucidated by detailed analysis of their NMR spectra, ECDs, HRESIMS, optical rotation, and X-ray crystallographic data, and by comparison with literature data as well. The antimicrobial activities of compounds 1 – 7 were evaluated.