title: New scalarane-based sesterterpenes from the sponge Phyllospongia madagascarensis.
abstract: Two new natural scalaranes, 16beta-acetoxy-20,24-dimethyl-12,24-dioxo-25-norscalarane and 12beta-hydroxy-20,24-dimethyl-13,18-oxa-25-norscalarane, were isolated from the Madagascaran sponge Phyllospongiamadagascarensis, together with three previously decribed tetracyclic sesterterpenoids, phyllofolactones F, G, and B, and a new artifactual ethyl ether of scalaradisin B. Structure determinations were based on NMR and other spectral data. Compounds 1 and 2 represent new examples of 20,24-dimethyl-25-norscalarane sesterterpenes, and compound 2 has a seven-membered oxacycle that makes its skeletal system unique.
authors.affiliation: Pacific Institute of Bioorganic Chemistry, Far East Branch of the Russian Academy of Sciences, Prospect 100 let Vladivostoku, 159, Vladivostok 690022, Russia.
authors.forename: Ljudmila P
authors.initials: LP
authors.lastname: Ponomarenko
authors.forename: Anatoly I
authors.initials: AI
authors.lastname: Kalinovsky
authors.forename: Valentin A
authors.initials: VA
authors.lastname: Stonik
mesh_terms: D000818:Animals; D008270:Madagascar; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011161:Porifera / Q000737:chemistry*; D054830:Sesterterpenes; D013329:Structure-Activity Relationship; D013729:Terpenes / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: C493117:12beta-hydroxy-20,24-dimethyl-13,18-oxa-25-norscalarane; C493116:16beta-acetoxy-20,24-dimethyl-12,24-dioxo-25-norscalarane; D054830:Sesterterpenes; D013729:Terpenes