title: New antifeedant C20 terpenoids from Leucosceptrum canum.
abstract: Three novel C(20) terpenoids, norleucosceptroids A-C (1-3), were isolated from the leaves and flowers of Leucosceptrum canum (Labiatae) and were identified by comprehensive spectroscopic analysis and, in the case of 1, single-crystal X-ray diffraction. Structurally, compounds 1-3 should be categorized as pentanor-sesterterpenoids rather than diterpenoids. Moderate antifeedant activity of 1-3 against the generalist plant-feeding insect Helicoverpa armigera was detected, suggesting that they might also be involved in the plant defense against insect herbivores.
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: Chun-Huan
authors.initials: CH
authors.lastname: Li
authors.forename: Shu-Xi
authors.initials: SX
authors.lastname: Jing
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiao-Nian
authors.initials: XN
authors.lastname: Li
authors.forename: Xu
authors.initials: X
authors.lastname: Zhao
authors.forename: Sheng-Hong
authors.initials: SH
authors.lastname: Li
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D004354:Drug Screening Assays, Antitumor; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D018922:HL-60 Cells; D006801:Humans; D019686:Lamiaceae / Q000737:chemistry*; D007915:Lepidoptera / Q000187:drug effects; D018515:Plant Leaves / Q000737:chemistry; D054830:Sesterterpenes / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D054830:Sesterterpenes; C579659:norleucosceptroid A; C579660:norleucosceptroid B; C579661:norleucosceptroid C