Essential oils and ethanol extract from Camellia nitidissima and evaluation of their biological activity

Camellia nitidissima, a well-known species of yellow Camellia, has undergone commercial cultivation as a new tea resource recently. Herein, the composition, antioxidant and antimicrobial activities of the essential oil and ethanol extract of C. nitidissima were investigated. The essential oils from the leaves and flowers of C. nitidissima were obtained by hydro-distillation. A total of 56 and 34 constituents accounting for 77.5 and 96.8% of the oils were identified by GC-MS. Linalool (35.8%), phytol (7.9%), cis-geranyl acetone (7.3%) and methyl salicylate (6.8%) were found to be the primary components in the leaf oil, while the flower oil was rich in α-eudesmol (34.3%), γ-eudesmol (31.5%) and linalool (11.1%). The ethanol extract of C. nitidissima leaves contained 281.04 mg gallic acid equivalent/g of total phenols. The antioxidant activities of the two oils and extract were evaluated by DPPH and ABTS radical-scavenging assays. The IC₅₀ values varied from 17.4 (extract) to 720.3 μg/mL (flower oil) for DPPH and from 28.8(extract) to 889.6 μg/mL (flower oil) for ABTS. Both essential oils exhibited moderate antioxidant activities, and the extract possessed strong effects close to ascorbic acid. Additionally, the antimicrobial activities of the oils and extract against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa were evaluated by agar dilution assay. No considerable bactericidal activities were observed for either essential oil or extract compared with ampicillin and tobramycin standards. The results indicated the extract was more efficient than the two essential oils against S. aureus (MIC = 0.625 mg/mL) and B. subtilis (MIC = 1.25 mg/mL).