Analysis of Cleistopholis patens leaf and trunk bark oils using combined GC- flame ionisation detection, GC-retention index, GC-MS and (13) C-NMR

• Published in: Phytochemical analysis 2013-11, Vol.24 (6), p.574-580
• Main Authors: Ouattara, Zana A, Boti, Jean Brice, Ahibo, Antoine Coffy, Casanova, Joseph, Tomi, Félix, Bighelli, Ange
• Format: Article
• Language: English
• Subjects: Annonaceae - chemistry; Cote d'Ivoire; Gas Chromatography-Mass Spectrometry; Nuclear Magnetic Resonance, Biomolecular; Plant Bark - chemistry; Plant Leaves - chemistry; Plant Oils - analysis; Sesquiterpenes, Germacrane - analysis; Sesquiterpenes, Germacrane - chemistry
• ISSN: 1099-1565
• DOI: 10.1002/pca.2435

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. 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. 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. 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. 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.