Chemical composition and antimicrobial and antioxidant activity of Helichrysum italicum (Roth) G.Don subspecies essential oils

The chemical composition and the antimicrobial and antioxidant activity of essential oils from two Helichrysum italicum (Roth) G.Don subspecies grown in Bulgaria were investigated. As a result, 95 compounds with concentrations above 0.05% were detected by GC/MS and 46 of them, mainly mono- and sesquiterpenes, representing 79.81% and 85.51% of the total content of the samples, were identified. The main constituents of the essential oil from Helichrysum italicum subsp. microphyllum (plant origin from Bosnia) were monoterpene α-pinene (20.84%) and sesquiterpene γ-curcumene (16.53%), followed by β-selinene (5.59%), ar-curcumene (4.39%), trans-caryophyllene (4.35%), β-diketone italidione I (4.32%), α-selinene (4.28%), and neryl acetate (3.81%). The sesquiterpene hydrocarbons were the dominant groups of chemical constituents in the essential oil, followed by the oxygenated aliphatic hydrocarbons. The main constituents in the H. İtalicum essential oil (plant origin from France) were neryl acetate (33.87%), γ-curcumene (8.84%), rosifoliol (5.46%), geranyl propionate (4.98%), αr-curcumene (4.31%), italidione I (3.56%), α-eudesmol (3.19%), and limonene (3.02%). The main class of chemical compounds was the oxygenated monoterpenes, followed by sesquiterpene hydrocarbons. H. İtalicum essential oil from France showed more pronounced antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, and the fungus Aspergillus brasiliensis, as well as stronger antioxidant potential.