四十五種常用精油與其主要化學成分抗氧化活性之比較研究   全文下載

Comparative Study of the Antioxidant Activity of Forty-five Commonly Used Essential Oils and their Potential Active Components

本研究目的為分析常用之四十五種精油與其主要之化學成分其清除ABTS+‧自由基、螯合亞鐵離子能力及還原能力之抗氧化能力研究。清除ABTS+‧自由基和還原能力以肉桂葉和丁香精油最為顯著。當肉桂葉和丁香精油樣品濃度於1 mg/mL時，分別能清除96.45 ± 0.01%和96.33 ± 0.01%的ABTS+‧自由基，半數有效抑制濃度（EC50）分別為12 μg/mL和10 μg/mL。當肉桂葉和丁香精油樣品濃度於10 mg/mL 時，分別能顯現相對於 BHA的119.42 ± 0.68%和112.92 ± 0.87%的還原能力。丁香酚是肉桂葉和丁香精油的主要成分，也是造成高清除ABTS+.自由基和還原能力的主因。螯合金屬離子之能力以羅勒精油最為顯著，其金屬螯合活性為57.84 ± 0.25%，半數有效抑制濃度為984 μg/mL。甲基胡椒酚是羅勒精油的主成分，也是造成高金屬螯合活性之主因。四十五種常用精油中，較高的酚類化合物含量就有相對較高之ABTS+‧自由基清除和還原能力。高電子密度的氧原子與低立體障礙的平面分子，是甲基胡椒酚具有較高金屬螯合能力的二個可能原因。

This study was to examine the in vitro antioxidant activities of forty-five commonly used essential oils and their major components. The oils and major components were subjected to screening for their possible antioxidant activity by measuring the ABTS+‧ radical scavenging ability, reducing power and metal chelating activity. The ABTS+‧ radical scavenging ability and reducing power of cinnamon leaf and clove bud essential oils are the best two among these essential oils. At the concentration of 1 mg/mL, cinnamon leaf (96.45 ± 0.01%) and clove bud (96.33 ± 0.01%) essential oils showed the strongest ABTS+‧ radical scav-enging ability. The EC50 values of cinnamon leaf and clove bud essential oils are 12 μg/mL and 10 μg/mL, respectively. At the concentration of 10 mg/mL, cinnamon leaf and clove bud essential oils showed reducing power of 119.42 ± 0.68% and 112.92 ± 0.87% relative to butylated hydroxyanisole (BHA), respectively. Eugenol is the main component of cinnamon leaf and clove bud essential oils that contributes significantly to their ABTS+‧ radical scavenging activity and reducing power. In the metal chelating activity test system, basil essential oil was determined to be 57.48 ± 0.25% and its EC50 value is 984 μg/mL. Methyl chavicol is the major component of the basil essential oil that attributes greatly to its metal chelating activity. The higher phenolic content may explain the higher ABTS+‧ radical scavenging and reducing power activity of the forty-five kinds of commonly used essential oils. High electron density of the oxygen atom and low steric hindrance of the plane molecule of the methyl chavicol are the two possibili-ties that account for its higher metal chelating ability.