School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, China.
J Chromatogr A. 2011 Jun 10;1218(23):3608-15. doi: 10.1016/j.chroma.2011.04.031. Epub 2011 Apr 16.
In this paper, the application of polyethylene glycol (PEG) aqueous solution as a green solvent in microwave-assisted extraction (MAE) was firstly developed for the extraction of flavone and coumarin compounds from medicinal plants. The PEG solutions were optimized by a mono-factor test, and the other conditions of MAE including the size of sample, liquid/solid ratio, extraction temperature and extraction time were optimized by means of an orthogonal design L(9) (3(4)). Subsequently, PEG-MAE, organic solvent-MAE, and conventional heating reflux extraction (HRE) were evaluated with nevadensin extraction from Lysionotus pauciflorus, aesculin and aesculetin extraction from Cortex fraxini. Furthermore, the mechanism of PEG-MAE was investigated, including microwave-absorptive property and viscosity of PEG solutions, the kinetic mechanism of PEG-MAE and different microstructures of those samples before and after extraction. Under optimized conditions, the extraction yields of nevadensin from L. pauciflorus, aesculin and aesculetin from C. fraxini were 98.7%, 97.7% and 95.9% in a one-step extraction, respectively. The recoveries of nevadensin, aesculin and aesculetin were in the range of 92.0-103% with relative standard derivation lower than 3.6% by the proposed procedure. Compared with organic solvent-MAE and conventional extraction procedures, the proposed methods were effective and alternative for the extraction of flavone and coumarin compounds from medicinal plants. On the basis of the results, PEG solution as a green solvent in the MAE of active compounds from medicinal plants showed a great promising prospect.
本文首次开发了聚乙二醇（PEG）水溶液在微波辅助提取（MAE）中的应用，用于从药用植物中提取黄酮类和香豆素类化合物。通过单因素试验优化 PEG 溶液，并通过正交设计 L(9)（3(4)）优化 MAE 的其他条件，包括样品尺寸、液固比、提取温度和提取时间。随后，通过从少花米口袋中提取新伐辛、从秦皮中提取秦皮苷和秦皮素，评价 PEG-MAE、有机溶剂-MAE 和常规加热回流提取（HRE）的效果。此外，还研究了 PEG-MAE 的机制，包括 PEG 溶液的微波吸收特性和粘度、PEG-MAE 的动力学机制以及提取前后这些样品的不同微观结构。在优化条件下，一步提取法从少花米口袋中提取新伐辛的得率为 98.7%，从秦皮中提取秦皮苷和秦皮素的得率分别为 97.7%和 95.9%。采用所提出的方法，新伐辛、秦皮苷和秦皮素的回收率在 92.0-103%之间，相对标准偏差低于 3.6%。与有机溶剂-MAE 和常规提取方法相比，该方法是从药用植物中提取黄酮类和香豆素类化合物的有效替代方法。基于这些结果，PEG 溶液作为 MAE 中药用植物中活性化合物的绿色溶剂具有广阔的前景。
