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

Chemical investigation of the marine algal-derived endophytic fungus <italic>Aspergillus alabamensis</italic> EN-547 resulted in the isolation of 4-<italic>epi</italic>-<italic>seco</italic>-shornephine A methyl ester (<bold>1</bold>) and 4-<italic>epi</italic>-<italic>seco</italic>-shornephine A carboxylic acid (<bold>2</bold>), two new secondary metabolites having a rare diketomorpholine motif, and 28-acetoxy-12<italic>β</italic>,15<italic>α</italic>,25-trihydroxyergosta-4,6,8(14),22-tetraen-3-one (<bold>3</bold>), a new highly conjugated ergostane-type steroid, together with four known metabolites (<bold>4</bold>–<bold>7</bold>). 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 <bold>1</bold>–<bold>7</bold> were evaluated. [ABSTRACT FROM AUTHOR]