title: Silphiperfolene-Type Terpenoids and Other Metabolites from Cultures of the Tropical Ascomycete Hypoxylon rickii (Xylariaceae).
abstract: A culture isolated from ascospores of Hypoxylon rickii, a xylariaceous ascomycete collected in Martinique, had yielded botryane, noreremophilane and abietane-type terpenoids in a preceding study, but additional metabolites were detected by extensive HPLC-MS analysis in other fractions. Herein we report the further isolation of four new sesquiterpenoids with a silphiperfol-6-ene skeleton from extracts of H. rickii. The planar structures were elucidated by NMR and HRMS data as 13-hydroxysilphiperfol-6-ene (1), 9-hydroxysilphiperfol-6-en-13-oic acid (2), 2-hydroxysilphiperfol-6-en-13-oic acid (3) and 15-hydroxysilphiperfol-6-en-13-oic acid (4). For compounds 2-4 we propose the trivial names rickinic acids A-C. Their stereochemistry was assigned by ROESY correlations as well as by the specific optical rotation. Additionally, the known compounds, botryenanol, dehydrobotrydienol, cyclo(Phe-Pro), cyclo(Pro-Leu), (+)-ramulosin and α-eleostearic acid were isolated. The antimicrobial and cytotoxic activities of the new compounds are also reported.
authors.affiliation: Department Microbial Drugs, Helmholtz Centre for Infection Research GmbH, Inhoffenstraße 7, 38124, Braunschweig, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Surup
authors.forename: Eric
authors.initials: E
authors.lastname: Kuhnert
authors.forename: Elena
authors.initials: E
authors.lastname: Liscinskij
authors.forename: Marc
authors.initials: M
authors.lastname: Stadler