Composition and antioxidant and antibacterial activities of essential oils from three yellow Camellia species

Key messageRemarkable differences between the chemical compositions of the essential oils from three yellow Camellias were found, and the antioxidant and antimicrobial activities of the three oils were reported for the first time.AbstractAlthough yellow Camellia is a popular tea tree with golden flowers, there is insufficient information available about its volatile constituents and biological activity. In the present work, the essential oils from the leaves of Camellia tunghinensis, Camellia nitidissima and Camellia euphlebia were obtained by hydrodistillation. A total of 75, 56 and 55 constituents, accounting for approximately 86.9%, 77.5% and 84.5% of the oils of C. tunghinensis, C. nitidissima and C. euphlebia, respectively, were identified. GC/MS analysis showed that the principal components of the oil of C. tunghinensis were n-hexanal (17.2%), 2-pentylfuran (10.6%), phytone (7.5%) and geranylacetone (5.0%). The oil of C. nitidissima is rich in linalool (35.8%), phytol (7.9%), geranylacetone (7.3%) and methyl salicylate (6.8%), while phytol (58%), geranylacetone (5.6%) and n-hexanal (3.3%) are the major constituents of the oil of C. euphlebia. The antioxidant activities of the three oils were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS) assays. The IC50 values of the oils varied from 42.82 to 164.98 mu g/mL for DPPH and from 120.56 to 321.91 mu g/mL for ABTS, which indicated that the three oils possess moderate antioxidant effects. Moreover, the antimicrobial activities of the oils were tested against four microorganisms (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) by the disc diffusion method. Except for Pseudomonas aeruginosa, the tested microorganisms were sensitive to the oils, and inhibition zones from 12.1 to 24.3mm were observed. The minimum inhibitory concentrations (MIC values) were determined to be 0.625-2.5mg/mL, indicating the oils had weak antibacterial effects.