title: Constituents of glandular trichomes of Tithonia diversifolia: relationships to herbivory and antifeedant activity.
abstract: The herbivory activity of the bordered patch larvae (Chlosyne lacinia, Lepidoptera) on leaves of a Brazilian population of Tithonia diversifolia and the antifeedant potential of its leaf rinse extract were investigated. The caterpillars fed only on the adaxial face, where the density of glandular trichomes is very low, and avoided the abaxial face, which contains high levels of trichomes. Deterrent activity against the larvae was observed in leaf discs treated with leaf rinse extract at concentrations of 1-5% of fresh leaf weight. High-performance liquid chromatography (HPLC) analysis indicated that sesquiterpene lactones are the main constituents of the glandular trichomes. Dichloromethane rinse extracts of the leaves and inflorescences were chemically investigated, and 16 compounds were isolated and identified: 14 sesquiterpene lactones, a flavonoid and a diterpenoid. In this study, five sesquiterpene lactones are described for the first time in the genus, including two lactones, one of which has an unusual seco-guaianolide skeleton. Our findings indicate that the caterpillars avoid the sesquiterpene-lactone-rich glandular trichomes, and provide evidence for the antifeedant activity of the dichloromethane leaf rinse extract. In addition, a study of the seasonal variation of the main constituents from the leaf surface throughout a year demonstrated that a very low qualitative but a very high quantitative variation occurs. The highest level of the main metabolite tagitinin C was observed between September and October and the lowest was from March to June, the later corresponding to the period of highest infestation by the larvae.
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Ribeirão Preto, SP, Brazil.
authors.forename: Sérgio Ricardo
authors.initials: SR
authors.lastname: Ambrósio
authors.forename: Yumi
authors.initials: Y
authors.lastname: Oki
authors.forename: Vladimir Constantino Gomes
authors.initials: VC
authors.lastname: Heleno
authors.forename: Juliana Siqueira
authors.initials: JS
authors.lastname: Chaves
authors.forename: Paulo Gustavo Barboni Dantas
authors.initials: PG
authors.lastname: Nascimento
authors.forename: Juliana Espada
authors.initials: JE
authors.lastname: Lichston
authors.forename: Mauricio Gomes
authors.initials: MG
authors.lastname: Constantino
authors.forename: Elenice Mouro
authors.initials: EM
authors.lastname: Varanda
authors.forename: Fernando Batista
authors.initials: FB
authors.lastname: Da Costa
mesh_terms: D000818:Animals; D019659:Asteraceae / Q000737:chemistry*; D004435:Eating / Q000187:drug effects / Q000502:physiology; D007313:Insecta / Q000187:drug effects* / Q000502:physiology*; D007814:Larva / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D012621:Seasons
chemical_list: D010936:Plant Extracts