Optimisation of Ultrasound‐assisted Extraction of Puerarin and Total Isoflavones from Puerariae Lobatae Radix (Pueraria lobata (Wild.) Ohwi) with Response Surface Methodology

Abstract

Isoflavones, particularly puerarin, are a group of important components from Puerariae Lobatae Radix (PLR) which show diverse pharmacological activities, therefore giving rise to the development of various extraction methods. Ultrasound-assisted extraction (UAE) has been explored for isoflavone extraction from PLR as it provides higher extraction efficiency compared with traditional methods. To optimise the UAE conditions for puerarin and total isoflavone extraction from PLR using response surface methodology (RSM). Samples were prepared by use of ultrasound-assisted extraction, and then subjected to HPLC analysis. Box-Behnken Design (BBD), a widely used form of RSM, was used for the optimisation of the UAE process. The effects of ethanol concentration, extraction time and the solvent-to-material ratio on the yields of puerarin and total isoflavones were investigated. The Box-Behnken experimental results demonstrate that optimal extraction was obtained with an ethanol concentration of 71.35%, an extraction time of 49.08 min and a solvent-to-material ratio of 21.72 for puerarin, and an ethanol concentration of 80.00%, an extraction time of 55.00 min and a solvent-to-material ratio of 12.81 for total isoflavones. The yields of puerarin and total isoflavones were 41 ± 0.63 mg/g and 128 ± 0.82 mg/g, respectively, under the optimised extraction conditions, which are in agreement with the values predicted by the RSM. The RSM allows for optimising the extraction parameters such that maximum extraction of puerarin and total isoflavones was achieved experimentally.