Essential Oil Composition and Volatile Profile of Seven Helichrysum Species Grown in Italy.

Helichrysum genus consists of about 600 species widespread throughout the world, especially in South Africa and in the Mediterranean area. In this study the aroma profile (HS-SPME) and the EO compositions of seven Helichrysum species (H. cymosum, H. odoratissimum, H. petiolare, H. fontanesii, H. saxatile, H. sanguineum, and H. tenax) were evaluated. All the plants were grown in Italy under the same growth conditions. The volatile constituents, particularly monoterpenes, depended by the plant's genotype and ecological adaptation. This study represents the first headspace evaluation on the selected plants and the results evidenced that monoterpenes represented the main class of constituents in five of the seven species analysed (from 59.2% to 95.0%). The higher content in sesquiterpene hydrocarbons was observed in the Mediterranean species of H. sanguineum (68.0%). Only H. saxatile showed relative similar abundance of monoterpenes and sesquiterpene hydrocarbons. The essential oil composition of the majority of examined species are characterised by high percentage of sesquiterpenes (especially β-caryophyllene and δ-cadinene) ranging from 51.3% to 92.0%, except for H. cymosum, H. tenax, and H. sanguineum leaves where monoterpenes predominated (from 51.7% to 74.7%).