title: Ergosterimide, a new natural Diels-Alder adduct of a steroid and maleimide in the fungus Aspergillus niger.
abstract: Ergosterimide (1), a natural Diels-Alder adduct of ergosteroid and maleimide, was characterized from the culture extract of Aspergillus niger EN-13, an endophytic fungus isolated from the marine brown alga Colpomenia sinuosa. In addition, four known steroids including (22E,24R)-ergosta-5,7,22-trien-3beta-ol (2), (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (3), (22E,24R)-5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol (4), and (22E,24R)-ergosta-7,22-dien-3beta,5alpha,6beta-triol (5) were also isolated and identified. The structures of these compounds were elucidated by extensive analysis of 1D and 2D NMR and IR spectra and MS data. The plausible biosynthetic pathway of 1 was also discussed. To the best of our knowledge, 1 is the first natural Diels-Alder adduct of steroid and maleimide reported so far.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Li
authors.forename: Peter
authors.initials: P
authors.lastname: Proksch
authors.forename: Bin-Gui
authors.initials: BG
authors.lastname: Wang
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism*; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D008301:Maleimides / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D008301:Maleimides; C525010:ergosterimide; D004875:Ergosterol