title: Defense sesterterpenoid lactones from Leucosceptrum canum.
abstract: Ten sesterterpenoids, leucosceptroids E-N (1-10), possessing an α,β-unsaturated γ-lactone moiety, were isolated from the leaves and flowers of a woody Labiatae, Leucosceptrum canum. Their structures including relative stereochemistry were determined by comprehensive 1D and 2D NMR, MS, and in the case of 1 and 10, by single crystal X-ray diffraction analyses. This class of unique plant terpenoids was designated as leucosceptrane sesterterpenoids (=leucosceptroids). The potent antifeedant activity of the most abundant compound, leucosceptroid G (3), and a representative compound, leucosceptroid N (10), against the generalist plant-feeding insect Helicoverpa armigera suggested that they might also be defense compounds of L. canum against insects.
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, PR China.
authors.forename: Shi-Hong
authors.initials: SH
authors.lastname: Luo
authors.forename: Juan
authors.initials: J
authors.lastname: Hua
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Niu
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Chun-Huan
authors.initials: CH
authors.lastname: Li
authors.forename: Yan-Ying
authors.initials: YY
authors.lastname: Zhou
authors.forename: Shu-Xi
authors.initials: SX
authors.lastname: Jing
authors.forename: Xu
authors.initials: X
authors.lastname: Zhao
authors.forename: Sheng-Hong
authors.initials: SH
authors.lastname: Li
mesh_terms: D000818:Animals; D007313:Insecta / Q000187:drug effects*; D007783:Lactones / Q000737:chemistry* / Q000494:pharmacology*; D019686:Lamiaceae / Q000737:chemistry*; D015394:Molecular Structure; D054830:Sesterterpenes / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D007783:Lactones; D054830:Sesterterpenes