title: Minor sesquiterpenes with new carbon skeletons from the brown alga Dictyopteris divaricata.
abstract: Five minor sesquiterpenes (1-5) with two novel carbon skeletons, together with a minor new oplopane sesquiterpene (6), have been isolated from the brown alga Dictyopteris divaricata. By means of spectroscopic data including IR, HRMS, 1D and 2D NMR, and CD, their structures including absolute configurations were assigned as (+)-(1R,5S,6S,9R)-3-acetyl-1-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0]non-3-ene (1), (+)-(1R,3S,4S,5R,6S,9R)-3-acetyl-1,4-dihydroxy-6-isopropyl-9-methylbicyclo[4.3.0]nonane (2), (+)-(1R,3R,4R,5R,6S,9R)-3-acetyl-1,4-dihydroxy-6-isopropyl-9-methylbicyclo[4.3.0]nonane (3), (+)-(1S,2R,6S,9R)-1-hydroxy-2-(1-hydroxyethyl)-6-isopropyl-9-methylbicyclo[4.3.0]non-4-en-3-one (4), (-)-(5S,6R,9S)-2-acetyl-5-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0]non-1-en-3-one (5), and (-)-(1S,6S,9R)-4-acetyl-1-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0]non-4-en-3-one (6). Biogenetically, the carbon skeletons of 1-6 may be derived from the co-occurring cadinane skeleton by different ring contraction rearrangements. Compounds 1-6 were inactive (IC(50) > 10 mug/mL) against several human cancer cell lines.
authors.affiliation: Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College (Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education), Bejing 100050, P.R. China.
authors.forename: Fuhang
authors.initials: F
authors.lastname: Song
authors.forename: Xiuli
authors.initials: X
authors.lastname: Xu
authors.forename: Shuai
authors.initials: S
authors.lastname: Li
authors.forename: Sujuan
authors.initials: S
authors.lastname: Wang
authors.forename: Jielu
authors.initials: J
authors.lastname: Zhao
authors.forename: Yongchun
authors.initials: Y
authors.lastname: Yang
authors.forename: Xiao
authors.initials: X
authors.lastname: Fan
authors.forename: Jiangong
authors.initials: J
authors.lastname: Shi
authors.forename: Lan
authors.initials: L
authors.lastname: He
mesh_terms: D004354:Drug Screening Assays, Antitumor; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D000459:Phaeophyceae / Q000737:chemistry*; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D004365:Drugs, Chinese Herbal; D012717:Sesquiterpenes