title: Bi-bicyclic and bi-tricyclic compounds from Dendrobium thyrsiflorum.
abstract: One bi-bicyclic and two bi-tricyclic derivatives of coumarin-benzofuran, phenanthrene-phenanthrene and phenanthrene-phenanthraquinone, along with seven known compounds, were isolated from stems of Dendrobium thyrsiflorum Rchb.f. (Orchidaceae). On the basis of chemical, NMR (1H, 13C, HMQC, HMBC and NOESY) and mass spectrometry data, their structures were elucidated as denthyrsin [3-(5',6'-dimethoxybenzofuran-2'-yl)-6,7-dimethoxy-2H-chromen-2-one; 1], denthyrsinol (4,5'-dimethoxy-[1,1']biphenanthrenyl-2,5,4',7'-tetraol; 2), and denthyrsinone (7,4',7'-trihydroxy-2,2',8'-trimethoxy-[5,1']biphenanthrenyl-1,4-dione; 3). Compounds 1-3 and denthyrsinin (1,5,7-trimethoxyphenanthrene-2,6-diol; 4) showed significant cytotoxic activities against Hela (13.5, 9.3, 9.9 and 2.7 microM, respectively), K-562 (0.45, 1.6, 6.0 and 2.3 microM, respectively) and MCF-7 (18.1, not tested, 3.5 and 4.8 microM, respectively) cell lines.
authors.affiliation: Department of Pharmacognosy, China Pharmaceutical University, Nanjing 210038, China.
authors.forename: Guang-Nong
authors.initials: GN
authors.lastname: Zhang
authors.forename: Ling-Yan
authors.initials: LY
authors.lastname: Zhong
authors.forename: S W Annie
authors.initials: SW
authors.lastname: Bligh
authors.forename: Ying-Li
authors.initials: YL
authors.lastname: Guo
authors.forename: Chao-Feng
authors.initials: CF
authors.lastname: Zhang
authors.forename: Mian
authors.initials: M
authors.lastname: Zhang
authors.forename: Zheng-Tao
authors.initials: ZT
authors.lastname: Wang
authors.forename: Luo-Shan
authors.initials: LS
authors.lastname: Xu
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D031667:Dendrobium / Q000737:chemistry*; D006801:Humans; D006844:Hydrocarbons, Cyclic / Q000737:chemistry* / Q000494:pharmacology; D015394:Molecular Structure; D018547:Plant Stems / Q000737:chemistry
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D006844:Hydrocarbons, Cyclic