本文采用分光光度法研究了14种植物精油在液相和气相状态下清除DPPH自由基的能力。实验结果显示不同精油对DPPH自由基有不同的清除效果，在液相和气相条件中，肉桂精油、百里香油、丁香精油的清除效果最好；进一步选取肉桂精油、百里香油、丁香精油进行复配，丁香精油分别与肉桂精油、百里香油复配产生了协同增效效应，特别是丁香精油和百里香油复配时在气相、液相中均具有很好清除DPPH自由基的效果；丁香精油与百里香油复配时，28 ℃的气相清除率明显高于19 ℃，19 ℃时丁香精油占60~80%会出现气相复配增效效应，而在28 ℃时占20~60%则出现气相复配增效效应，在液相时丁香精油占40~80%出现复配增效效应。在不同的复配比例中，复配物中的不同抗自由基活性成分间会产生协同增效效应。

The 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging capacities of 14 types of essential oils in the gas and liquid phases were studied via spectrophotometry. The essential oils exhibited different DPPH free radical scavenging capacities. Under liquid and gas phase conditions, cinnamon, thyme, and clove essential oils exhibited the best scavenging capacities. Furthermore, cinnamon, thyme, and clove essential oils were used to prepare compounded essential oils, and the clove essential oil produced synergistic effects with the cinnamon and thyme oils. In particular, the compounded essential oil prepared from thyme and clove essential oils had good DPPH scavenging capacities in both the liquid and gas phases. When clove essential oil was compounded with thyme oil, the rate of DPPH radical scavenging in the gas phase at 28 ℃ was obviously higher than that at 19 ℃. Synergistic effects in the gas phase at 19 ℃ and 28 ℃, as well as in the liquid phase were appeared when clove essential oil accounted for 60% to 80%, 20% to 60%, and 40% to 80%, respectively. With different compounding ratios, the different anti-free radical active ingredients of the compound could produce synergistic effects.

广东省部产学研合作专项资金(2012A090300010，2012B091100477，2011A090200004)；广东省自然科学基金博士启动项目（S2012040007305）