茶樹精油的使用歷史悠久，主要萃取方法為水蒸餾萃取其枝葉所得，成分為萜烯類化合物組成，如單萜烯類、倍半萜烯類，以及衍生醇類。由於茶樹精油的主成分Terpinen-4-ol具有良好的生物活性功能，使茶樹精油的應用從抗菌性，抗黴菌、抗病毒，以及抗癌性等，建立精油在醫藥、香粧品、以及日常用品等領域的重要性。在國際間有限的供給下，如何有效率的萃取出精油為重要課題，本研究期望在相同原料質量中，能萃取更多精油，故引入實驗設計法，除了探討水蒸餾萃取時間、萃取液/茶樹原料比例對產率的影響，並加入食品級的非離子型界面活性劑 Tween 20，期望輔助萃取效率。茶樹精油由於受到國際重視，國際標準組織制訂世界通用的茶樹成分標準，促使茶樹精油國際化時，可以減少技術性的差異與障礙，在國際標準ISO 4730中規範了15種茶樹精油成分，本研究以其中9種含量較高之成分為分析成分，並評估其抗菌與抗癌活性。
　　在中央合成設計 (Central Composite Design, CCD) 中，影響茶樹精油萃取最顯著的因子為時間、時間×時間；最高萃取效率條件為Tween 20濃度3000 ppm、萃取液/茶樹原料比例22.5，以及萃取時間135分鐘。以此條件執行驗證實驗，加入校正因子於預測產率後，實際產率與預測值相近，放大實驗尺寸亦可以得到相近的產率；而將精油成分分析，得到主成分Terpinen-4-ol與萃取時間關係，當萃取時間越長，Terpinen-4-ol所占比例降低。與市售茶樹精油比較溶解度測試中，本研究之茶樹精油有更好的溶解效果，溶液也具有良好穩定性；在抑菌活性的定性實驗中，茶樹精油對大腸桿菌以及金黃色葡萄球菌皆展現抑菌效果，在大腸桿菌試驗中更與抗生素安比西林有相同的抑菌圈大小；抗癌實驗中，本研究茶樹精油對MG-63骨肉瘤細胞，於24小時的 IC50 為0.021%，48小時的 IC50 為0.015%，展現有效抑制癌細胞生長。

The aim of this study is to evaluate the effects of added surfactant (Tween 20), the ratio of extractant liquid/ Melaleuca alternifolia (tea tree) leaf (aka, liquid/solid ratio), extraction time and the block on the extraction yield of tea tree oil (TTO). A central composite design (CCD) was used to optimize the processing condition of the extraction from tea tree leaves. The significant interactions of factors terms were the extraction time and the cross factor of extraction time×extraction time. Moreover, the optimal processing conditions showed as follows: concentration of surfactant: 3000 ppm, liquid/solid ratio: 22.5, and the processing time: 135 min. Under these conditions, the confirmation experiment was close to the predicted values calculated from the polynomial response surface model equation with a corrected factor. The composition of tea tree oil of the CCD was analyzed by GC-FID. The higher levels of main component, terpinen-4-ol, was found in short extraction time. The tea tree oil was focused on the stability of its microemulsion formulations compared to the commercial tea tree oil, antibacterial and anticancer properties. Tea tree oil had higher solubility in the microemulsion formulation than the commercial tea tree oil. Moreover, the stability of the microemulsion was determined by particle size measurement with dynamic light scattering (DLS) machine. Both of their microemulsion were stable for over 30 days. To evaluate the antibacterial activity, the disc diffusion method under in vitro conditions was prepared. Tea tree oil has fairly better antibacterial activity against Escherichia coli TOP10 and Staphylococcus aureus than the commercial tea tree oil. In addition, dose-dependent cytotoxicity of tea tree oil towards human tumor cell line, MG-63, was using the MTT assay. The IC50 values were given 0.021% (v/v) at 24 h and 0.015% (v/v) at 48 h for MG-63 respectively.

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