Extraction of essential oils from tea tree (<i>Melaleuca alternifolia</i>) and lemon grass (<i>Cymbopogon citratus</i>) using betaine‐based deep eutectic solvent (DES)
Natsuki Mori, Toyonobu Usuki
Abstract
Abstract Introduction The essential oils of tea tree ( Melaleuca alternifolia ) leaves mainly contain eucalyptol, α‐terpinene, ‐terpinene, and terpinen‐4‐ol and have anti‐bacterial, anti‐fungal, anti‐infective, and anti‐inflammatory actions. The essential oils of lemon grass ( Cymbopogon citratus ) leaves mainly contain neral, geranial, and geraniol and have anti‐microbial and anti‐fungal activities and hypocholesterolemic effect. Objectives The present study describes the use of low‐toxicity solvents called betaine‐based deep eutectic solvents (DESs) for efficient extraction of essential oils from tea tree and lemon grass. H 2 O and EtOH were used for extraction as control methods. Methodology Quantitative analysis was performed using gas chromatography–mass spectrometry (GC–MS) in selected ion monitoring mode. Scanning electron micrography (SEM) and antioxidant assays for extracted samples were also conducted. Results The results indicated that extraction for tea tree using betaine/sucrose (molar ratio 2:1) improved the yields of terpinolene and eucalyptol 2.5‐ and 1.9‐fold, respectively, compared with the control method. In lemon grass, extraction using betaine/sucrose (molar ratio 2:1) improved the yields of neral and geranial 1.9‐ and 1.7‐fold, respectively, compared with the control method. Conclusion These results demonstrated the effective extraction of essential oils from plant leaves under milder conditions than those needed for the conventional methods. The environmentally benign DESs for the extraction would be applicable to the food and cosmetic industries.