Optimization of Microwave Extraction Conditions for Antioxidant Phenolic Compounds from Ligustrum lucidum Aiton Using Response Surface Methodology

ABSTRACT Response surface methodology (RSM) was applied to optimize the microwave-assisted extraction (MAE) conditions for electron-donating ability, total phenol content, and total flavonoid content of Ligustrum lucidum Aiton. Ligustrum lucidum Aiton from different regions was tested, and Ligustrum lucidum Aiton from Haenam was chosen due to its higher total phenolic content, total flavonoid content, DPPH radical scavenging activity and ABTS radical scavenging activity compared to the other samples. Central composite design was used to optimize extraction of Ligustrum lucidum Aiton from Haenam as well as determine the effects of extraction temperature (X1) and extraction time (X2) on dependent variables (Yn). Determination coefficients (R2) of the regression equations for dependent varia-bles ranged from 0.8858 to 0.9517. The optimum points were 131.68°C for extraction temperature and 5.49 min for extraction time. Predicted values of the optimized conditions were acceptable when compared to experimental values