Comparative study on the essential oils of six Hawk tea (Litsea coreana Levl. var. lanuginosa) from China: Yields, chemical compositions and biological activities

Hawk tea, prepared from the young leaves of Litsea coreana Levl. var. ianuginosa, is consumed as a tonic in China. Essential oils (EOs) from Hawk tea collected from six habitats in China were obtained by hydro distillation. Extraction yields ranged from 0.42% (g/g) in samples from Ningguo to 0.11% (g/g) in samples from Qingchuan. A total of 50 compounds in the six 30 samples were identified by Gas Chromatography-Mass Spectrometer. The dominant compounds were citral (4.67-21.12%), caryophyllene (2.31-15.74%), dodecanal (2.10-15.38%), alpha-humulene (1.45-13.56%) and decanal (1.91-13.17%). Altitude may contribute the greatest effect on the chemical variation of the six EO samples. All the EO samples showed bioactivities. Among them, the EOs from the Pingshan sample showed the best ABTS radical scavenging activity (78.67 mg TEs /g) and better antimicrobial activities (MIC = 156.25-625 mu g/mL) and had stronger DPPH radical scavenging activity (IC50 = 0.71 mg/mL) than BHT (IC50 = 0.76 mg/mL). The EOs from the Ningguo sample showed the highest reducing power (26.06 mg Fe2+/g) in a FRAP assay, the best inhibitory effect on alpha-glucosidase (1.71 mg/mL) and was the most cytotoxic (66.03-77.03 mu g/mL) in an MTS assay. Therefore, the EOs from Hawk tea could be suitable for commercialization in the food, cosmetic or medical industries. Due to the activities of their FIN, plants growing in Pingshan and Ningguo are the optimal candidates.