title: Analysis of Cleistopholis patens leaf and trunk bark oils using combined GC- flame ionisation detection, GC-retention index, GC-MS and (13) C-NMR.
abstract: BACKGROUND
  Germacrenes A-C are secondary metabolites produced by various plants. They are sesquiterpene hydrocarbons bearing the (E,E)-1,5-cyclodecadiene structure known to undergo thermal rearrangement through a [3.3]-sigmatropic reaction. Such a rearrangement was evidenced by comparing the contents of a given germacrene and the corresponding elemene calculated by GC-flame ionisation detection (FID) with the relative intensities of the signals of both molecules in the (13) C-NMR spectrum of the mixture, recorded at room temperature.
  
  
  OBJECTIVE
  To develop a protocol to identify and quantify germacrenes A, B and C and in parallel the corresponding elemenes, using a combination of GC-FID and (13) C-NMR and then provide a correct analysis of Cleistopholis patens essential oils.
  
  
  METHODS
  The essential oil was submitted to GC-FID, GC-retention index, GC-MS and (13) C-NMR analyses. The relative percentages of every couple of germacrene and elemene measured by GC-FID were summed. Then, the relative ratio of the mean intensities of the signals of the protonated carbons of a given germacrene and the corresponding elemene was calculated. The contents of both compounds were obtained by combining GC-FID and (13) C-NMR data.
  
  
  RESULTS
  The true content of germacrene A/β-elemene, germacrene B/γ-elemene and germacrene C/δ-elemene in leaf and root oils from C. patens was evaluated by combination of GC-FID and (13) C-NMR data. Correct analysis of the essential oils was provided.
  
  
  CONCLUSIONS
  Combined analysis of essential oil including (13) C-NMR without isolation of the components, appeared really efficient to identify and quantify germacrene isomers and in parallel elemene isomers in essential oils.
authors.affiliation: Université de Corse-CNRS, UMR 6134 SPE, Equipe Chimie et Biomasse, Route des Sanguinaires, 20000, Ajaccio, France; Laboratoire de Chimie Organique Biologique, UFR-SSMT, Université Félix Houphouët-Boigny, BPV 34, Abidjan, Côte d'Ivoire.
authors.forename: Zana A
authors.initials: ZA
authors.lastname: Ouattara
authors.forename: Jean Brice
authors.initials: JB
authors.lastname: Boti
authors.forename: Antoine Coffy
authors.initials: AC
authors.lastname: Ahibo
authors.forename: Joseph
authors.initials: J
authors.lastname: Casanova
authors.forename: Félix
authors.initials: F
authors.lastname: Tomi
authors.forename: Ange
authors.initials: A
authors.lastname: Bighelli
mesh_terms: D029061:Annonaceae / Q000737:chemistry*; D007560:Cote d'Ivoire; D008401:Gas Chromatography-Mass Spectrometry; D019906:Nuclear Magnetic Resonance, Biomolecular; D024301:Plant Bark / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000032:analysis*; D045788:Sesquiterpenes, Germacrane / Q000032:analysis* / Q000737:chemistry
chemical_list: D010938:Plant Oils; D045788:Sesquiterpenes, Germacrane
keywords: 13C-NMR; Cleistopholis patens; elemene; essential oil composition; germacrene