市售42 種精油之DPPH 自由基清除能力、總酚含量測定及主要化學成分分析之研究   全文下載

DPPH Free-Radical Scavenging Activity, Total Phenolic Contents and Chemical Composition Analysis of Forty-Two Kinds of Essential Oils

本研究主要為分析市售42 種精油之二苯聯苦基（1, 1-Diphenyl-2-picrylydrazyl，DPPH）自由基清除能力、總酚含量及主要化學成分。當精油濃度為5 mg/mL 時，肉桂枝之DPPH 自由基清除能力最高（91.4 ± 0.002），總酚含量相當於658.40 ± 4.383 μg 的沒食子酸，其次為野馬鬱蘭（86.66 ± 0.008）及野生百里香（52.54 ± 0.016），總酚含量則分別相當於1107.20 ± 0.768 μg 及275.50 ± 0.607 μg 的沒食子酸。將肉桂枝精油及野馬鬱蘭精油與標準品2，6- 二第三丁基羥基苯甲醚（Butyl Hydroxy Anisole，BHA）進行比較，其半數有效抑制濃度（EC50）的順序為BHA（25.11 μg/mL）< 肉桂枝（90.63 μg/mL）< 野馬鬱蘭（751.51 μg/mL），其結果與DPPH 自由基清除能力一致。利用光化學放光（Photochemiluminescence ，PCL）試驗方法，檢測三種精油中脂溶性物質之抗氧化力，結果顯示每克之肉桂枝精油抗氧化力相當於133.9 ± 0.26 μmol 之 trolox 為最高，其次為野馬鬱蘭（62.63 ± 1.73 μmol trolox/g）及野生百里香（5.88 ± 0.16 μmol trolox/g）。最後藉由氣相層析質譜儀（GC-MS）分析精油之化學成分，並將含量較高之化學成分再與精油本身進行DPPH 自由基清除率測試，由測試結果可得知造成肉桂枝精油、野馬鬱蘭精油及野生百里香精油清除率高之原因分別來自於丁香酚、百里香酚及香芹酚之作用。"

Forty-two commonly used essential oils were investigated for the antioxidant capabilities by DPPH free-radical scavenging activity, total phenolic contents and photochemiluminescence (PCL) assay. At the concentration of 5 mg/mL, cinnamon bark (91.4 ± 0.002%), origanum (86.66 ± 0.008%) and thyme wild (52.54 ± 0.016%) were shown to own the strongest DPPH free-radical scavenging activity. Their total phenolic contents were 658.40 ± 4.383, 1107.20 ± 0.768 and 275.50 ± 0.607 (μg GAE / 5 mg essential oil), respectively. To compare with the standard reference BHA (μg/mL), their EC50 were in the order: BHA (25.11 μg/mL) < cinnamon bark (90.63 μg/mL) origanum (62.63 ± 1.73 μmol trolox/g) > theme wild (5.88 ± 0.16 μmol trolox/g). The chemical compositions of cinnamon bark, origanum and thyme wild were analyzed by GC-MS and followed by DPPH free-radical scavenging activity assay to confirm that eugenol, carvacrol and thymol were the major compositions contributing the antioxidative capabilities of the essential oils.