关键词: 红花玉兰花蕾挥发油；超临界CO2萃取；气相色谱-质谱联用；抗氧化活性；抗菌活性

Abstract: In order to investigate the effect of drying methods for flower buds on the extraction, antioxidant and antibacterial activities of essential oil from Magnolia wufengensis, essential oils from the flower buds of Magnolia wufengensis ‘Jiaohong 1’ dried by freeze drying, shade drying, sun drying or oven drying at 55 ℃ were obtained by supercritical CO2 fluid extraction and analyzed for chemical composition by using gas chromatography-mass spectrometry (GC-MS) combined with retention index (RI). Furthermore, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging and reducing power assays were used to evaluate the antioxidant activity of the essential oils. Disk diffusion method was used to measure the antibacterial activity. The results indicated that the highest essential oil yield was obtained from the freeze-dried sample, up to (2.736 ± 0.138)%, and in total 49 compounds were identified in the essential oils from the four dried samples, among which, 26 compounds were found to be present in the essential oil from the freeze-dried sample, the most abundant being γ-sitosterol and 4H-xanthalongia; and 20, 20 and 30 compounds in the essential oils from the sun-dried, oven-dried and shade-dried samples, respectively, the most abundant being γ-sitosterol and hydrocarbon. The antioxidant activity of the four essential oils was in the decreasing order of freeze drying > shade drying > sun drying > oven drying, all of which had broad-spectrum antibacterial activity. In general, freeze drying is the best pretreatment method for extracting essential oils from the buds of M. wufengensis.

Key words: essential oils from buds of Magnolia wufengensis; supercritical CO2 fluid extraction; gas chromatography-mass spectrometry; antioxidant activity; antibacterial activity