白千層葉子精油成分分析及活性探索

Component analysis and bioactivity investigation of leaf essential oil from Melaleuca leucadendra

白千層（Melaleuca leucadendra）為台灣重要造林樹種之一，具優良的耐旱、耐鹽、抗風、抗二氧化硫能力，適合作為行道樹、海岸防風林、工業區綠美化樹種。目前為止並沒有關於白千層葉子精油成分及其活性之具體研究，因此本研究使用水蒸氣蒸餾法及水蒸餾法來萃取白千層葉子精油，並比較不同製備方法之精油收率並分析其組成成分，同時比較採集自不同地區的白千層樹葉之成分差異及評估其抗發炎、抗氧化活性。試驗結果顯示，不同株之白千層所得之精油收率會有所不同，收率為10至24 mL/kg。以水蒸餾法製備精油時，收率隨著萃取時間的增加而增加。本研究並利用氣相層析質譜儀，自白千層葉子精油中鑑定出32種成分，而不同萃取方法、時間與地區所得之精油成分均是以Viridiflorol和1,8-Cineole為最主要成分，但在一些微量的成分會有所差異。由主成分（PCA）分析，可作為精油產地辨識之用。最後，經由DPPH自由基能力測試，結果顯示白千層精油之抗氧化能力不顯著；但在抗發炎活性評估方面，證實白千層精油對RAW 264.7小鼠巨噬細胞株之 NO產生有顯著的抑制效果。參考化合物薑黃素之自由基半數抑制濃度（IC50）值為6.5 μg/mL，雖然1 hr萃取時間所得之葉子精油於100 μg/mL濃度下亦無法表現出抗發炎活性，但隨著萃取時間的增加，葉子精油的抗發炎活性顯著的增加，9 hr的精油之IC50為49.09 μg/mL，且試驗濃度下並不具細胞毒性，值得進一步的開發其藥用保健活性。 Melaleuca leucadendra is an important plantation tree species in Taiwan, with the ability of drought tolerance, salt tolerance, wind resistance and anti-sulfur dioxide, is suitable as street trees, windbreaks at coast and greening trees in the industrial area. So far, there isn't any research about the component analysis and bioactivity investigation of leaf essential oil from M. leucadendra. There are two methods we used in this research, including steam distillation and water distillation, to extract the essential oil from leaf. The variation of yield and compositions of essential oils prepared from different trees and extraction methods were analyzed in this study. According to the results, obtained in this study, the yields of essential oil are different for each tree, the variation is from 10 mL/kg to 24 mL/kg. Moreover, the yields were increased when prolonged the extraction time in the water distillation method. There are 32 compounds identified from the leaves essential oils by using GC/MS analysis. Although the minor compositions for different trees are slight different, the major compounds, i.e. Viridiflorol and 1,8-Cineole, are same for each essential oils. We further demonstrated that it would be possible to distinguish the origin of essential oils by using PCA analysis. Finally, we could not find the significant antioxidative activity for leaves essential oils, based on the results obtained in DPPH radical scavenging assay. However, the essential oil possessed the anti-inflammation activity to inhibit the NO production in the LPS-induced acute inflammation in mice macrophage. The IC50 value is 49.09 μg/mL for the essential oils extracted with 9 hr.