β citronellal

Bornyl acetate (99%), camphene (95%), camphor (96%), carvarol (98%), (−)-carveol (95%), (+)-carvone (96%), β-caryophyllene (98.5%), caryophyllene oxide (95%), β-citronellal (95%), citral (95%), 1,8-cineole (99%), p-cymene (99%), decyl chloroformate (97%), dodecanoic acid (98%), β-farnesene (90%), geranyl acetate (97%), geraniol (98%), isopulegol (98%), linalool (97%), limonene (97%), limonene oxide (97%), methyl linolenate (99%), myrcene (90%), myristic acid (99%), palmitic acid (99%), α-phellandrene (85%), α-pinene (98%), pivalic acid (99%), sabinene (75%), α-terpineol (90%), γ-terpinene (97%), 4-terpineol (95%), terpinolene (90%), and tymol (99%) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Achillea millefolium L. flowers, Citrus aurantium L. fruits, Leptospermum petersonii F. M. Bailey leaves, Ruta graveolens L. leaves, and Thymus vulgaris L. leaves were collected from a local store in Chonju, Korea. Sample specimens were authenticated by Jeongmoon Kim at Chonbuk National University, Korea. Essential oils of the five plants were obtained by steam distillation extraction, and finally dried over Na₂SO₄ to extract the pure essential oils (Table 1).

The standards, including β-Myrcene (90.0%), Limonene (99.0%), terpinolene (94.0%), cis-rose oxide (96.0%), cis-furan linalool oxide (98.0%), linalool (96.0%), 4-terpinenol (95.0%), menthol (98.0%), β-citronellal (99.0%), myrtenol (95.0%), α-terpineol (99.0%), nerol (98.0%), neral, geraniol (97.0%), and geranial (98.0%), were obtained from Sigma-Aldrich (St. Louis, MO, USA). In total, 98% of 4-methyl-2-pentanol (internal standard) was also obtained from Sigma-Aldrich. The purified water used in this research was obtained from a Master Touch purification system (Shanghai, China). Polyvinylpolypyrrolidone (PVPP) was a product of huayueyang (Beijing, China). SYBR^® Premix Ex TaqTM and Plant Total RNA Kit were respectively purchased from TaKaRa Bio (Otsu, Shiga, Japan) and Gene-Better Life Science (Beijing, China). The reverse transcription system kit was purchased from Promega (Madison, WI, USA). All other reagents used in this study were obtained from the Beijing Chemical Works (Beijing, China), unless otherwise specified.