title: Three biscembranoids and their monomeric counterpart cembranoid, a biogenetic Diels-Alder precursor, from the soft coral Sarcophyton elegans.
abstract: Two new cembranoids, methyl tetrahydrosarcoate ( 1) and methyl tetrahydroisosarcoate ( 2), were isolated from the soft coral Sarcophyton elegans, collected at Kitangambwe Kenya, together with four biscembranoids, the known nyalolide ( 3) and the unprecedented desacetylnyalolide ( 4), diepoxynyalolide ( 5), and dioxanyalolide ( 6). The structures and relative stereochemistry of the compounds were elucidated by interpretation of MS, 1D NMR, COSY, HSQC, HMBC, and NOESY experiments. Compound 1 is most likely the dienophile affording, by a Diels-Alder reaction, the four biscembranoids. Dioxanyalolide ( 6) possesses antibacterial activity against Escherichia coli at a concentration of 1.25 microg/mL. Methyl tetrahydrosarcoate ( 1) and diepoxynyalolide ( 5) exhibited LC 50 values of 1.5 microM in a brine shrimp bioassay, while desacetylnyalolide ( 4) was only mildly active.
authors.affiliation: School of Chemistry and Department of Zoology, Tel-Aviv University, Ramat Aviv, Israel.
authors.forename: Ashgan
authors.initials: A
authors.lastname: Bishara
authors.forename: Amira
authors.initials: A
authors.lastname: Rudi
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Benayahu
authors.forename: Yoel
authors.initials: Y
authors.lastname: Kashman
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry*; D001156:Artemia / Q000187:drug effects; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D007630:Kenya; D015394:Molecular Structure; D013729:Terpenes / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D004224:Diterpenes; D013729:Terpenes; C527001:methyl tetrahydrosarcoate; C492401:nyalolide