Application of ionic liquids in the microwave-assisted extraction of podophyllotoxin from Chinese herbal medicine

摘要

A micelle-mediated extraction technique, i.e. ionic liquid-based microwave-assisted extraction (ILs-nMAE) technique has been developed for the effective extraction of podophyllotoxin from three Chinesenmedicinal plants. Several operating parameters were successively optimized by single-factor and L9 (34)northogonal array experiments. 1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-decyl-n3-methylimidazolium tetrafluoroborate ([demim][BF4]) and 1-allyl-3-methylimidazoliumntetrafluoroborate ([amim][BF4]) were selected as the optimal surfactants for Dysosma versipellis,nSinopodophyllum hexandrum and Diphylleia sinensis, respectively. Compared with other extractionntechniques, such as ionic liquids-based maceration extraction (ILs-ME), heat extraction (ILs-HE) andnultrasound-assisted extraction (ILs-UAE), the ILs-MAE technique not only took a shorter time butnalso afforded a higher extraction rate of podophyllotoxin from the herbs. Reversed phase highnperformance liquid chromatography was employed for the analysis of podophyllotoxin. The resultsnshowed that the linearity for analyzing podophyllotoxin in all three herbs was in the concentrationnrange of 0.005–0.4 mg mLu00011 with the correlation coefficient between 0.9993 and 0.9996. LODs weren2.05–2.58 mg mLu00011 and RSDs of inter-day stability were less than 5.8%. Repeatability and intermediatenprecision were separately lower than 3.3% and 6.3%. The recoveries for podophyllotoxin extracted withnthe ILs-MAE technique were in the range of 97.1–102% and all RSDs were lower than 3.0%.nFurthermore, the mechanism of ILs-MAE was preliminarily studied by means of kinetic mechanism,nsurface structures and chemical compositions of samples before and after different extractionntechniques. On the basis of the destruction of herb surface microstructures and high solubility of ILs,nthe ILs-MAE technique eventually got the maximum yield value.