The essential oil of Hypericum hirsutum was analysed for the first time. Twenty-seven components were identified. The non-terpene compounds had the highest contribution (46.6%). A low monoterpenes content (1.3%) characterized the oil. The major constituents were n-undecane (32.2%), patchoulene (11.8%) and caryophyllene oxide (9.3%), which are not significantly represented in the essential oils of other species of the genus Hypericum examined. Copyright

For the first time the composition of the essential oil of Hypericum maculatum Crantz has been determined by GC and GC-MS. The oil consisted of a large number of components in low percentages. Only five components exceeded a 5% level:ˇ-farnesene (10.0%), n-undecane (8.2%),ˇ-caryophyllene (7.6%), υ-cadinene (7.2%) and -muurolene (5.2%). The oil showed strong antimicrobiological activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, Klebsiella pneumoniae, Bacillus subtilis, Sarcina lutea, Aspergillus niger and Candida albicans, documented in vitro by MIC and MMC values.

The essential oil of Hypericum olympicum L. was analysed for the first time and was compared to the essential oil of Hypericum perforatum L. from the same location. Eighteen components were common for both species. The main components of H. olympicim oil were (E)-anethole (30.7%) andˇ-farnesene (12.4%), and for H. perforatum oil they wereˇ-caryophyllene (14.2%) and 2-methyl-octane (13.1%).

The essential oil of Hypericum atomarium Boiss. was analysed for the first time. Seven components were identified, accounting for 83.6% of the total oil. The three most abundant components (isocaryophyllene, y-cadinene and 2.4 diisopropenyl-i-methyl-i-vinyl-cyclohexane) represented 64.5% of the oil. A high content of sesquiterpenes (79.6%) characterized the oil

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