title: Cytotoxic hydroazulene diterpenes from the brown alga Dictyota dichotoma.
abstract: Two new hydroazulenoid (prenyl guaiane) diterpenes, dictyone acetate (2) and 3,4-epoxy 13-hydroxy pachydictyol A (4) were isolated from the petroleum ether fraction of the alcoholic extract of the brown alga, Dictyota dichotoma (Hudson) Lamouroux, which was collected from the Red Sea coasts at Hurgada, Egypt, together with three known ones, pachydictyol A (1), dictyone (3) and 11-hydroxypachydictyol A (dictyol E) (5). In addition, the steroidal compound, stigmasta-5,(E)-24(28)-dien-3-beta-ol (fucosterol) (6) was also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt.
authors.forename: Sahar R
authors.initials: SR
authors.lastname: Gedara
authors.forename: Osama B
authors.initials: OB
authors.lastname: Abdel-Halim
authors.forename: Saleh H
authors.initials: SH
authors.lastname: el-Sharkawy
authors.forename: Osama M
authors.initials: OM
authors.lastname: Salama
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Shier
authors.forename: Ahmed F
authors.initials: AF
authors.lastname: Halim
mesh_terms: D016475:3T3 Cells; D000473:Alkanes; D000818:Animals; D002470:Cell Survival / Q000187:drug effects*; D002472:Cell Transformation, Viral; D003603:Cytotoxins / Q000737:chemistry* / Q000302:isolation & purification; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D010578:Petroleum; D000459:Phaeophyceae / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D012623:Seawater
chemical_list: D000473:Alkanes; D003603:Cytotoxins; D004224:Diterpenes; D010578:Petroleum; D010936:Plant Extracts; C004544:naphtha