The essential oil of juniper berries (Juniperus communis L., Cupressaceae) is traditionally used for medicinal and flavoring purposes. As elucidated by gas chromatography/flame ionization detector (GC/FID) and gas chromatography/mass spectrometry (GC/MS methods), the juniper berry oil from Bulgaria is largely comprised of monoterpene hydrocarbons such as α-pinene (51.4%), myrcene (8.3%), sabinene (5.8%), limonene (5.1%) and β-pinene (5.0%). The antioxidant capacity of the essential oil was evaluated in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging, 2,2-azino-bis-3-ethylbenzothiazoline-6 sulfonic acid (ABTS) radical cation scavenging, hydroxyl radical (ОН^•) scavenging and chelating capacity, superoxide radical (^•O₂⁻) scavenging and xanthine oxidase inhibitory effects, hydrogen peroxide scavenging. The antioxidant activity of the oil attributable to electron transfer made juniper berry essential oil a strong antioxidant, whereas the antioxidant activity attributable to hydrogen atom transfer was lower. Lipid peroxidation inhibition by the essential oil in both stages, i.e., hydroperoxide formation and malondialdehyde formation, was less efficient than the inhibition by butylated hydroxytoluene (BHT). In vivo studies confirmed these effects of the oil which created the possibility of blocking the oxidation processes in yeast cells by increasing activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx).

The specific physiological responses induced by inhaling R-(-)- as well as S-(+)-linalool in 24 human subjects undergoing experimental stress were investigated in this study. Various physiological parameters of the autonomous nervous system (heart rate, blood pressure, electrodermal activity) as well as the endocrine system (salivary cortisol) were monitored. The study clearly indicated that odorants can modulate salivary cortisol levels, with both linalool enantiomers exerting relaxing effects. Concerning blood pressure and heart rate, S-(+)-linalool acted as an activating agent in contrast to electrodermal activity. R-(-)-linalool proved to be stress-relieving as determined by heart rate. In conclusion, the results revealed that (1) chirality crucially influences the physiological effects of odorants and that (2) odorants may act differently on certain physiological parameters.

The pure aromatic volatiles p-cymene, carvacrol, eugenol and thymol as well as commercial essential oils of Cinnamomum zeylanicum, Origanum vulgare, Pimenta dioica, Pimenta racemosa, Satureja hortensis, Syzygium aromaticum, Thymus vulgaris and Trachyspermum ammi were investigated concerning antimicrobial activities. Therefore, these samples and, as reference substances, synthetic antibiotics and the natural antimicrobial components carveol, m-, o- and p-cresol were tested against strains of two Gram-positive and five Gram-negative bacteria and the yeast Candida albicans using agar dilution and agar diffusion methods. The analysis of the chemical composition of the essential oils by means of GC and GC/MS focusing on aromatic volatiles produced the following results: C. zeylanicum: eugenol (74.9%); O. vulgare: carvacrol (66.1%) and p-cymene (9.2%); P. dioica: eugenol (76.0%); P. racemosa: eugenol (45.6%); S. hortensis: carvacrol (41.5%), p-cymene (10.7%) and thymol (8.7%); S. aromaticum: eugenol (76.8%); T. vulgaris: thymol (43.4%), p-cymene (23.5%) and carvacrol (4.1%); T. ammi: thymol (43.7%) and p-cymene (17.7%). All investigated aromatic volatiles and essential oils exhibited strong effects against the yeast Candida albicans and medium to strong antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus and Enterococcus faecalis and the Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, and Salmonella sp., whereas weaker effects were observed against Pseudomonas aeruginosa.

In the present study, the chemical composition and antioxidant potential of an essential oil of ginger rhizomes from Ecuador was elucidated. The analysis of the essential oil by GC/FID/MS resulted in identification of 71 compounds, of which the main are citral (geranial 10.5% and neral 9.1%), α-zingiberene (17.4%), camphene (7.8%), α-farnesene (6.8%) and β-sesquiphellandrene (6.7%). The in vitro antioxidant activity of the essential oil expressed by IC₅₀ in descending order is: hydroxyl radical (OH^•) scavenging (0.0065 μg/mL) > chelating capacity (0.822 μg/mL) > 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS^•+) scavenging (3.94 μg/mL) > xanthine oxidase inhibition (138.0 μg/mL) > oxygen radical (CV) scavenging (404.0 μg/mL) > 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•) scavenging (675 μg/mL). Lipid peroxidation inhibition of the essential oil was less efficient than butylhydroxy-toluol (BHT) in both stages, i.e. hydroperoxide and malondialdehyde formation. In vivo studies in Saccharomyces cerevisiae demonstrated a significant dose-dependent increase in antioxidant marker enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), blocking the oxidation processes in yeast cells. Moreover, ginger essential oil in concentrations of 1.6 mg/mL increases the viability of cells to oxidative stress induced by H₂O₂.