Essential Oils from The Dropped Flowers of Camellia japonica: Extraction Optimization, Chemical Profile and Antibacterial Property

Camellia japonica is one of the most economically valuable species that can be taxonomically placed in the Theaceae family. Many horticultural varieties of C. japonica have been cultivated as ornamental trees worldwide, owing to their charming flowers. However, young C. japonica flowers usually drop in a “decapitated” form during the peak flowering stage, causing a resource waste. In this study, Essential Oils from the Dropped C. japonica Flowers (EODCJF) were extracted with hydrodistillation and process was optimized by response surface methodology. The chemical profile and antibacterial activity were tested by gas chromatography-mass spectrometry and by disc diffusion, respectively. The optimal extraction parameters were: Immersion time of 9 h, extraction time of 8 h and liquid-to-solid ratio of 39: 1 (mL/g), under these conditions, the yield was 3.20%. The actual yield was in compliance with the predicted result with an error margin of 3.61%. Thirty-three volatile compounds accounting for 94.46% were authenticated in EODCJF with alkanes of 53.96% and alcohols of 28.59%, respectively. EODCJF exerted certain antibacterial capacities against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Bacillus pumilus. Their antibacterial activities could be contributed by the long-chain alcohols in EODCJF and alkanes may potentiate the dispersion of these liposoluble alcohols in EODCJF.