Submitted to: Separation and Purification Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2009
Publication Date: 9/1/2009
Citation: Wang, X., Zheng, X., Lan, Y., Li, C., Shi, J., Xue, S.J. 2009. Application of response surface methodology to optimize microwave-assisted extraction of silymarin from milk thistle seeds. Separation and Purification Technology. 70:34-40. Interpretive Summary: Silymarin is a substance isolated from milk thistle seeds that has been used widely in herbal remedies for almost 200 years. Extracts of milk thistle seeds have a long tradition for treating liver ailments. New extraction methods are needed to reduce extraction times, decrease solvent volumes, and increase the yield of extracts. Although microwave-assisted extraction has been widely recognized as a simple, effective, and versatile extraction method, little information has been published on the use of microwave technology for the extraction of silymarin from milk thistle seeds. Results show that microwave-assisted extraction offers an ultra-fast extraction time of one hour as compared to at least eight hours using conventional methods, yielding almost the same quantity of extracts. Microwave-assisted extraction applied to silymarin from milk thistle seeds can be an alternative technique to the time- and energy-consuming conventional methods.
Technical Abstract: Several parameters of Microwave-assisted extraction (MAE) including extraction time, extraction temperature, ethanol concentration and solid-liquid ratio were selected to describe the MAE processing. The silybin content, measured by an UV-Vis spectrophotometry, was considered as the silymarin yield. A mathematical regression model was established to accurately predict the extraction yield of silymarin. The optimum extraction process was obtained as follows: extraction time of 60min, extraction temperature of 112', 81.5% (v/v) ethanol concentration, solid-liquid ratio 1:38 (g/mL). Under such conditions, the experimental value of the silymarin yield after extraction for three times was 56.67mg/g. A comparison among MAE and Soxhlet (SE) and reflux (RE) extractions indicates that MAE is a potential alternate method for the extraction of silymarin from milk thistle seeds.