Citronellol

Phenylethanol, limonene and α-terpinene (pract.) were purchased from Fluka Chemie GmbH (Buchs, Switzerland). Camphene (95%), β-damascone (>95%), citronellyl acetate (>95%), β-damascenone natural, (+)-β-pinene (analytical standard), (−)-β-pinene (99%), (+)-α-pinene (≥99%), (−)-α-pinene (analytical standard), farnesol (95%), geranyl acetate (>99%), linalool (97%), p-cymene (99%), rose oxide (cis/trans mixture) and cis-3-hexen-1-ol (internal standard (IS), 98%) were purchased from Sigma Aldrich (St. Louis, MO, USA). Eugenol and β-caryophyllene were obtained from Systema Natura GmbH (Flintbek, Germany). Citral (cis/trans mixture, >98%) and neryl acetate (>95%) were purchased from TCI Chemical (Eschborn, Germany). Citronellol (95%), geraniol (99%) and nerol (97%) were obtained from Acros Organics (Geel, Belgium), and methyleugenol and n-heptane (99.9%) were purchased from Carl Roth GmbH (Karlsruhe, Germany) and VWR chemicals (Schlieren, Switzerland), respectively. Authentic rose oil samples and other EOs were purchased in Swiss pharmacies and online. All samples were stored at room temperature and in brown glass vials. Helium 6.0, nitrogen 6.0 and hydrogen 5.0 gas were purchased from PanGas (Dagmersellen, Switzerland).

Trans-cinnamaldehyde, eugenol, and terpineol were obtained from Sigma-Aldrich (Lisbon, Portugal); citronellol was obtained from Acros Organics (Morris, NJ, USA) (Table 1). The EOs were dissolved in dimethyl sulfoxide (DMSO, Sigma-Aldrich, St. Louis, MO, USA). Control experiments were performed to ascertain the growth inhibitory effects in DMSO (5%–10%, v v⁻¹).

The Bacopa caroliniana herb was purchased from a local horticulture market (Taichung, Taiwan). The chemicals α-pinene (≥95%), β-pinene (≥96%), p-cymene (≥90%), sabinene (≥92%), linalool (≥97%), nerolidol (≥95%), α-terpineol (≥90%), 4-terpineol (≥95%), β-caryophyllene (≥85%), β-caryophyllene oxide (≥95%), 1-octen-3-ol (≥95%), 1,8-cineole (≥90%), α-terpinolene (≥92%), were obtained from K. F. Lings Co. (Taoyuan, Taiwan). Citronellol (≥95%) and α-terpinene (≥90%) was acquired from Alfa Aesar. Myrcene (≥90%) and γ-terpinene (≥97%) were purchased from Acros Organics. Limonene (≥95%), acetylthiocholine iodide, and 5,5-dithio-bis (2-nitrobenzoic acid) were purchased from Sigma-Aldrich Co.

DPPH, β-carotene, linoleic acid, chloroform, 5-LOX, α-tocopherol, Griess reagent, glycerol mono-oleate, sodium nitroprusside, sodium sulfate, 95% ethanol, Tween20, and Tween40 were purchased from Sigma-Aldrich (St. Louis, MO, USA). Methanol, l-ascorbic acid, 99% sodium chloride, and sodium phosphate dibasic were purchased from J.T. Baker (Phillipsburg, NJ, USA). l-Tyrosine and tyrosinase were purchased from Worthington (Lakewood, NJ, USA). 96% α-Bisabolol, 96% citronellal, and 95% citronellol were purchased From Alfa Aesar (Heysham, UK). Modified letheen broth was purchased from Oxoid (Basingstoke, UK). Agar, yeast extract, malt extract, peptone, and malt extract broth were purchased from HiMedia (Mumbai, India). Dextrose anhydrous was purchased from Nihon Shiyaku Reagent (Tokyo, Japan). Deionized distilled water was purified by the Milli-Q system (Millipore, Bedford, MA, USA).

Ultrapure 18.3 MΩ⋅cm water used for these experiments was produced from a Zeneer Power III TOC system (Human Corp., Seoul, Korea). All the following reagents were purchased from Sigma Aldrich, unless stated otherwise, and were standard grade: butyl acetate, hexanal (Alfa Aesar, Haverhill, MA, USA), butanol, 3-methyl-1-butanol (Alfa Aesar), (E)-hex-2-enal (Alfa Aesar), hexanol, (Z)-hex-3-en-1-ol (Alfa Aesar), nonanal, 2-ethyl-1-hexanol, acetophenone, α-terpineol, benzyl alcohol, 2-phenylethanol, ethyl tetradecanoate, ethyl dodecanoate, methyl 2-hydroxybenzoate (Alfa Aesar), citronellol, ethyl decanoate, benzaldehyde (Alfa Aesar), ethyl octanoate, ethyl heptanoate, isoamyl acetate, limonene, 2-methyl-1-butanol, ethyl hexanoate, ethyl acetate, ethyl butanoate, Saccharomyces cerevisiae (Franke, Italy), (NH₄)₂HPO₄ (Franke, Italy), K₂S₂O₅ (Franke, Italy), tartaric acid, polyvinylpolypyrrolidone (Alfa Aesar), sodium azide (Alfa Aesar), NaOH, Na₂PO₄(H₂O)₂, citric acid, HCl, 3-octanol, MeOH, CH₂Cl₂, β-glucosidase enzyme (Ecozim AROM, CRC Biotek, Roma, Italy), hydrocarbon mixture from C8–C23 (Sigma-Aldrich, St. Louis, MO, USA).