Optimization of ionic liquid-based microwave-assisted extraction of isoflavones from Radix puerariae by response surface methodology

Abstract

Objective: The aim of this work was to develop a based microwave-assisted approach for extraction of isoflavonoids from the herbal medicines.Background: Room temperature ionic liquids (RTILs) as a design green solvent are regarded as an attractive alternative or replacement to conventional volatile organic solvents. The microwave-assisted extraction has been applied widely to extract natural products. But the extracting solvents used often include organic solvents, which have strong volatility and toxicity and can cause serious pollution issues. The extraction technique that combines microwave extraction technology with ionic liquids for application in the field of extraction and separation constitutes a new approach.Method: [bmim]Br was selected as the solvent. The microwave-assisted extraction parameters, including extraction time, extraction temperature, microwave power, and the concentration of [bmim]Br had been concerned. Response surface methodology was used to develop predictive models for simulation and optimization of the extraction process. The multivariate quadratic regression equation was obtained by Central Composite Design. The response surfaces were determined by using the yields of total isoflavonoids as response values. HPLC and SEM were performed to compare the ionic liquid based microwave extraction with the traditional alcohol MAE.Results: The optimum extraction conditions were: extraction temperature of 70oC, extraction time of 8 min, microwave power of 400 W, and the concentration of [bmim]Br of 1.2 mol/L. The extraction yield of total isoflavonoids was 10.09%, which is well in close agreement with the value predicted by the model.Conclusion: Compared to conventional organic solvents, the ionic liquid based MAE could provide higher extraction yields and take much shorter extraction time.