Optimization of Microwave-Assisted Extraction of Antioxidant Compounds from Roots of Polygonum multiflorum Thunb. at Vietnam using Response Surface Methodology

Response surface methodology (RSM) was used to optimize the extraction conditions for the determination of total phenolic content (TPC), total flavonoid content (TFC) and Antioxidant Activity (DPPH) in the roots of Polygonum multiflorum Thunb.using Microwave-Assisted Extraction (MAE).The process variables were extraction temperature (40 -60 o C), extraction time (30 -60 min), ethanol concentration (30 -70 %) and microwave power (300 -500 W).The results showed that temperature, time, ethanol concentration and microwave power had significant impacts on TPC, TFC and DPPH.The optimum extraction conditions obtained with RSM were: extraction temperature of 53 o C, extraction time of 49 min, ethanol concentration of 48 % and microwave power level of 420 W. The experimental values obtained for TPC, TFC and DPPH radical scavenging activity were 34.15 0.2 mg GAE/g, 6.52 0.15 mg QE/g and 93.82 0.3 %, respectively.