Volatile constituents of four Helichrysum species growing in Greece

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, includ ing nonacosane (11.1%), and also caryophyllene epoxide (4.4%), while the oi l 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 mixtu re of four eudesmol isomers (31.4%), Analysis of oils before and after anth esis showed some significant quantitative differences. In H. doerfleri carv acrol increased noticeably, while in H. italicum ssp microphyllum the conte nt of alpha-pinene reduced from 5.2% to a trace. Besides showing species-sp ecific patterns in volatile oils, these four Mediterranean species differed from other Helichrysum analysed in the dominance of sesquiterpenes over mo noterpenes. Furthermore, two of the four species contained aliphatic hydroc arbons nor previously recorded in the genus. (C) 2000 Elsevier Science Ltd. All rights reserved.