Optimization and comparison of three methods for extraction of volatile compounds from Cyperus rotundus evaluated by gas chromatography–mass spectrometry

The essential oil of Cyperus rotundus has multiple pharmacological activities. Therefore, the extraction with high yield and quality is very important for preparation of essential oil of C. rotundus. In this paper, three methods, namely hydrodistillation (HD), pressurized liquid extraction (PLE) and supercritical fluid extraction (SFE), for extraction of volatile compounds from C. rotundus were optimized and compared by gas chromatography–mass spectrometry. Among eight identified compounds in C. rotundus, five components including α-copaene, cyperene, β-selinene, β-cyperone and α-cyperone were quantitatively determined or estimated using α-cyperone as standard, which showed that PLE had the highest extraction efficiency, while SFE had the best selectivity for extraction of β-cyperone and α-cyperone. The contents of ingredients from C. rotundus extracted with HD, PLE and SFE are significantly different, which suggest that comparison of chemical components and pharmacological activities of different extracts is helpful to elucidate the active components in C. rotundus and control its quality.