Rapid determination of S-(+)-linalool in leaf of Cinnamomum osmophloeum ct. linalool using ultrasound-assisted microextraction

摘要

Cinnamomum osmophloeum ct. linalool is one chemotype of indigenous cinnamon in Taiwan. Its leaf essential oil (LEO) and main component S -(+)-linalool both possess great anxiolytic activities. The aim of this study was to establish ultrasound-assisted microextraction (UAME) for extracting LEO from C. osmophloeum ct. linalool. The absolute content of S -(+)-linalool and chemical composition of LEO were analyzed using GC-MS and GC-FID. To obtain the optimal conditions for UAME, four parameters (ultrasonic extraction duration, power of ultrasound, times of extraction, and leaf weight of extraction) were investigated according to the S -(+)-linalool content extracted. Results showed that the optimal condition was 10?mg of leaf extracted using n -hexane in an ultrasonicator with ultrasonic power of 80?W for 1?min. Furthermore, the absolute content of S -(+)-linalool obtained by UAME (28.3 ± 0.5?mg/g leaf) was comparable with that extracted by the 30-min hydrodistillation (HD) (26.9 ± 2.7?mg/g leaf). UAME was then employed to extract S -(+)-linalool from leaves at different stages of maturity (young, semi-mature, and mature). Results indicated that only mature leaf contains large amounts of S -(+)-linalool. Of note is that the LEO extracted by UAME contains coumarin, while that extracted by HD does not. Coumarin is an important ingredient in a number of cosmetic products due to its odor-fixing properties. With UAME, the leaf of C. osmophloeum ct. linalool has potential to be used as an aromatic material for further applications. In conclusion, UAME established in the present study provides a simple and rapid method for the determination of S -(+)-linalool and chemical composition of LEO from C. osmophloeum ct. linalool.