Volatile constituents of four Helichrysum species growing in Greece
2000
Roussis, V. | Tsoukatou, M. | Petrakis, P.V. | Chinou, I. | Skoula, M. | Harborne, J.B.
The essential oils obtained by steam distillation from the aerial parts of 38 populations of four Helichrysum species were analysed by GC-MS. The oil of Helichrysum orientale notably contained four linear hydrocarbons, including nonacosane (11.1%), and also caryophyllene epoxide (4.4%), while the oil of H. heldreichii was dominated by E-caryophyllene (38.5%). By contrast, the oil of H. italicum ssp microphyllum was characterised by beta-selinene (17.2%) and gamma-curcumene (13.7%), while that of H. doerfleri had a mixture of four eudesmol isomers (31.4%). Analysis of oils before and after anthesis showed some significant quantitative differences. In H. doerfleri carvacrol increased noticeably, while in H. italicum ssp microphyllum the content of alpha-pinene reduced from 8.2% to a trace. Besides showing species-specific patterns in volatile oils, these four Mediterranean species differed from other Helichrysum analysed in the dominance of sesquiterpenes over monoterpenes. Furthermore, two of the four species contained aliphatic hydrocarbons not previously recorded in the genus.
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