title: ent-Beyerane diterpenoids from the heartwood of Excoecaria parvifolia.
abstract: Chromatographic fractionations of the toluene extract of the heartwood of Excoecaria parvifolia collected in Australia resulted in the isolation of 12 beyerane diterpenes (1-12), and the triterpene, lupeol. Four of the isolated diterpenoids (5-7 and 12) have unusual structures: ent-3-oxa-beyer-15-en-2-one, (5); ent-15,16-epoxy-2-hydroxy-19-norbeyer-1,4-dien-3-one (6); methyl ent-2,4-seco-15,16-epoxy-4-oxo-3,19-dinorbeyer-15-en-2-oate (7); and ent-2,17-dihydroxy-19-norbeyer-1,4,15-trien-3-one (12). The structures were established by spectroscopic analyses, NMR data comparisons with similar diterpenes, and chemical correlations. All the diterpenes are assumed to have the same absolute configuration as the co-occurring (+)-stachenol (4). Diosphenol 2 and nor-lactone 5 exhibited significant potency in bioassays for cytotoxic activity against leukemia cells (L1210). Plausible biosynthetic pathways are proposed to explain the origin of the diterpene metabolites.
authors.affiliation: Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, 1201 S Dorner Drive, Urbana, IL 61801, USA.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Grace
authors.forename: Juan A
authors.initials: JA
authors.lastname: Faraldos
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Lila
authors.forename: Robert M
authors.initials: RM
authors.lastname: Coates
mesh_terms: D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification*; D019665:Euphorbiaceae / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010938:Plant Oils / Q000737:chemistry; D014934:Wood
chemical_list: D004224:Diterpenes; D010938:Plant Oils