title: Phenanthrene derivatives from the orchid Coelogyne cristata.
abstract: Coeloginanthridin, a 9,10-dihydrophenanthrene derivative, and coeloginanthrin, the corresponding phenanthrene analogue, were isolated from the orchid Coelogyne cristata which earlier afforded coelogin (1a) and coeloginin (1b). The structures of coeloginanthridin and coeloginanthrin were established as 3,5,7-trihydroxy-1,2-dimethoxy-9,10-dihydrophenanthrene (2a) and 3,5,7-trihydroxy-1,2-dimethoxyphenanthrene (2c), respectively, from spectral and chemical evidence including the conversion of coeloginanthridin triacetate (2b) to coeloginanthrin triacetate (2d) by dehydrogenation with DDQ. In the light of earlier reports on structurally similar compounds, 2a and 2c may have biological activities of phytoalexins and endogenous plant growth regulators.
authors.affiliation: Department of Chemistry, University College of Science, 92, Acharya Prafulla Chandra Road, 700 009, Calcutta, India. priyalalm@hotmail.com
authors.forename: P L
authors.initials: PL
authors.lastname: Majumder
authors.forename: S
authors.initials: S
authors.lastname: Sen
authors.forename: S
authors.initials: S
authors.lastname: Majumder
mesh_terms: D015394:Molecular Structure; D029595:Orchidaceae / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry / Q000302:isolation & purification*; D013057:Spectrum Analysis
chemical_list: D010616:Phenanthrenes; C031181:phenanthrene