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 5.2% 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 nor previously recorded in
the genus. (C) 2000 Elsevier Science Ltd. All rights reserved
