title: Sesquiterpenes from Celastrus vulcanicola as photosynthetic inhibitors.
abstract: Three new sesquiterpenoids (1- 3) with a dihydro-beta-agarofuran skeleton were isolated from Celastrus vulcanicola. Their structures were elucidated on the basis of spectroscopic analysis, including homonuclear and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC, and HMBC), and the absolute configurations were determined by circular dichroism and chemical correlations. Their effects on photosynthesis were tested. Sesquiterpene 1 (50 microM) inhibits both light-dependent synthesis of ATP and the electron flow in chloroplasts, whereas at high concentrations the electron flow inhibition was partially reversed. Therefore, 1 behaves as a Hill reaction inhibitor and a weak energy transfer inhibitor and has two targets of interaction: one located at the oxygen-evolving complex, and the other located at the light-activated Mg (2+)-ATPase. Compound 2 was inactive, whereas 3 acts with the same mechanisms as 1 but was less active. Celastrus vulcanicola J. Donnell Smith (Celastraceae) is a subtropical woody vine distributed in Central America and the Caribbean. Its chemical constituents and biological activity have not yet been investigated.
authors.affiliation: Instituto Universitario de Bio-Orgánica Antonio González, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Torres-Romero
authors.forename: Beatriz
authors.initials: B
authors.lastname: King-Díaz
authors.forename: Ignacio A
authors.initials: IA
authors.lastname: Jiménez
authors.forename: Blas
authors.initials: B
authors.lastname: Lotina-Hennsen
authors.forename: Isabel L
authors.initials: IL
authors.lastname: Bazzocchi
mesh_terms: D031247:Celastrus / Q000737:chemistry*; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D010788:Photosynthesis / Q000187:drug effects*; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D012717:Sesquiterpenes