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

Chemical investigation of the marine algal-derived endophytic fungus EN-547 resulted in the isolation of 4---shornephine A methyl ester () and 4---shornephine A carboxylic acid (), two new secondary metabolites having a rare diketomorpholine motif, and 28-acetoxy-12,15,25-trihydroxyergosta-4,6,8(14),22-tetraen-3-one (), a new highly conjugated ergostane-type steroid, together with four known metabolites (-). 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 - were evaluated.