干燥方法对欧薄荷精油化学成分及生物活性的影响

Effect of Drying Method on Composition and Bioactivity of Essential Oil of Mentha longifolia L.

干燥方法是影响精油组成成分和品质的主要因素之一,为研究干燥方法对欧薄荷精油产率、组成成分及生物活性的影响,以阴干、晒干、40℃烘干3种不同方法对采自新疆阿克苏地区的生长期野生欧薄荷地上部分进行干燥处理。以新鲜未经干燥处理的欧薄荷为对照,水蒸气蒸馏法提取欧薄荷精油,研究了干燥方法对精油产率的影响。通过气相色谱-四极杆-飞行时间质谱联用仪分析了精油化学成分、气相色谱-氢火焰离子检测器分析了精油化学成分的相对含量,研究了干燥方法对欧薄荷精油组成成分及其含量的影响。通过DPPH自由基清除实验及ABTS阳离子自由基清除实验研究了干燥方法对欧薄荷精油抗氧化活性的影响,并用纸片扩散法研究了干燥方法对精油抑菌活性的影响。结果表明:干燥方法对欧薄荷精油产率、化学成分及生物活性有显著影响。其中阴干欧薄荷精油产率最高(0.49%±0.01%),其次是40℃烘干(0.42%±0.03%)、晒干(0.19%±0.02%)和新鲜(0.12%±0.03%)。精油中主要成分均为香芹酮(46.58%~50.75%)和柠檬烯(24.01%~29.71%),但含量上有显著区别。抗氧化及抑菌实验结果表明:从3种经干燥处理过的欧薄荷植物中提取出的精油,其抗氧化活性彼此之间无显著差异,但都远远高于新鲜欧薄荷精油,抑菌效果也较新鲜欧薄荷精油有不同程度增强,综合精油产率及生物活性,阴干可作为欧薄荷较佳干燥方法。

Drying method is one of the main factors affecting the composition and quality of essential oil.In order to study the effect of drying method on the yields,compounds and biological activities of the essential oil extracted from Mentha longifolia L.,shade-drying,sun-drying and oven-drying at 40℃were used to dry the aerial part of Mentha longifolia L.in growing period which collected from Aksu of Xinjiang.In comparison with essential oil extracted from fresh Mentha longifolia L.,steam-distillation was used to extract essential oils of Mentha longifolia L.,and the effects of drying methods on the yields of essential oils were analyzed.Gas chromatography-quadrupole-time-of-flight-mass spectrometry was used to analyze the chemical composition of essential oil.The Gas chromatography-flame ionization detector was used to analyze the relative contents of compounds in essential oils,and the effects of drying methods on the composition and content of essential oil of Mentha longifolia L.was studied.DPPH and ABTS radical scavenging tests were used to study the effect of drying methods on the antioxidant activities of essential oil,and disk diffusion method was used to study the effect of drying methods on the antibacterial activities of essential oil.The results showed that drying methods had significant effect on the yields,composition and bioactivities of essential oil.The highest yield of essential oil was found in the shade-drying Mentha longifolia L.(0.49%±0.01%),followed by oven-drying at 40℃(0.42%±0.03%),sun-drying(0.19%±0.02%)and fresh Mentha longifolia L.(0.12%±0.03%).Carvone(46.58%-50.75%)and limonene(24.01%-29.71%)were the main compounds of essential oil.However,the contents had significant differences.The results of antioxidant and antibacterial tests showed that there was no significant difference of antioxidant activity among the essential oil of Mentha longifolia L.extracted from three drying methods.However,antioxidant and antibacterial activities were much higher than the essential oil obtained from fresh Mentha longifolia L..According to the yield and biological activities of essential oil,shade-drying could be considered as the best drying method of Mentha longifolia L..