seasonal variation of mono- and sesquiterpenes in the essential oil of pycnocycla spinosa decne. ex boiss.

pycnocycla spinosa aerial parts were collected weekly during four-month growth. hydrodistillation and gas chromatography coupled with mass spectroscopy techniques were used for essential oil and sesquiterpenes investigation. thirty-four components were identified, of which the characteristic sesquiterpenes were a -copaene, caryophyllene, a -humulene, b-ionene, d-cadinene, a -calacorene, caryophyllen oxide, a -cadinol, and b-eudesmol. the content of b-eudesmol in the essential oil varied 1.9-9.17%, and of a -cadinol did 0-5.59%. plant harvested in jun provided essential oil with high caryophyllen oxide. these results may indicate that essential oil of differ qualities can be obtained according to the harvest time of the plant.