Effects of Extraction Methods on Volatile Oil Profiles of Cinnamomi ramulus–Zingiberis rhizoma recens Couplet Medicines

Abstract

Cinnamomi ramulus (CR, Guizhi in Chinese) and Zingiberis rhizoma recens (ZRR, Shengjiang in Chinese) are couplet medicines (drug pairs or drug combinations) in traditional Chinese medicine prescriptions. They contain a high amount of volatile oils which endow them with unique flavors and pharmacological activities. Extraction methods have a great influence on the extraction efficiency and composition of volatile oils. Firstly, the volatile oils of CR and ZRR were extracted by steam distillation (SD) and analyzed by GC-MS to obtain their chemical profiles. In total, 35 and 55 compounds were identified in the volatile oils of CR and ZRR, respectively. In order to find a suitable extraction method for the couplet medicine CR-ZRR, subsequently, steam distillation (SD), azeotropic distillation (AD) and supercritical fluid extraction (SFE) were applied to extract the volatile oils from CR-ZRR. The average extraction yields by SD, AD and SFE were 0.573%, 0.62% and 2.135%, respectively. The chemical composition of the volatile oils was then analyzed by GC-MS. In total, 73, 59 and 71 compounds were identified from the extracts obtained by SD, AD and SFE, respectively. Principal component analysis (PCA) and OPLS-DA showed that citral, (E)-cinnamaldehyde dimethyl acetal, zingiberene, cinnamaldehyde and β-sesquiphellandrene were the main contributors to distinguish the volatile oils that were obtained by different processes. Considering the chemical diversity and the total content of the main bioactive components of the volatiles oils, SD was more suitable for CR-ZRR volatile oil extraction. This study provides a basis for elucidating the chemical composition and suitable extraction method for the volatile oils of CR-ZRR.