State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
J Chromatogr A. 2010 Apr 16;1217(16):2441-6. doi: 10.1016/j.chroma.2009.12.022. Epub 2009 Dec 21.
The simultaneous ultrasonic and microwave assisted extraction (UMAE) technique was first employed to obtain phenolics. The effects of UMAE variables including extraction time, microwave power, and solvent to solid radio on the yield of phenolics were investigated. The optimized conditions were as follows: solvent to solid ratio was 20:1 (ml/g), extraction time was 30s, microwave power was 500W and two times of extraction. Moreover, the phenolic yield of UMAE was higher than that by maceration, indicating a significant reduction of extraction time and an improvement of efficiency. The phenomenon is related to the strong disruption of leaf tissue structure by microwave induced expansion and ultrasonic shaking, which had been observed with the scanning electron microscopy. The phenolic compositions of the extract was then identified by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), 10 compounds had been characterized, providing a more complete identification of phenolic compounds in burdock leaves than previously reported. The occurrence of benzoic acid and p-coumaric acid is reported for the first time. This study suggests that UMAE is a good alternative for the extraction of phenolics, with a great potential for industrial application. Also, UMAE provides a new sample preparation technique for characterization of the phenolic compounds from plants.
首次采用超声辅助微波萃取（UMAE）技术提取酚类物质。考察了萃取时间、微波功率和溶剂固比等 UMAE 变量对酚类物质产率的影响。优化条件为：溶剂固比为 20:1（ml/g），萃取时间为 30s，微波功率为 500W，萃取 2 次。此外，UMAE 的酚类物质产率高于浸渍法，表明萃取时间显著缩短，效率提高。这一现象与微波诱导的叶片组织结构强烈膨胀和超声振动有关，这一现象可以通过扫描电子显微镜观察到。然后通过超高效液相色谱串联质谱（UPLC-MS/MS）对提取物的酚类成分进行鉴定，鉴定出 10 种化合物，比以前的报道更完整地鉴定了牛蒡叶中的酚类化合物。首次报道了苯甲酸和对香豆酸的存在。本研究表明，UMAE 是一种提取酚类物质的良好替代方法，具有很大的工业应用潜力。此外，UMAE 为植物中酚类化合物的特征分析提供了一种新的样品制备技术。
