Extraction, antioxidant capacity and identification of Semen Astragali Complanati (Astragalus complanatus R. Br.) phenolics.

A study about the ultrasonic extraction, antioxidant capacity and identification of phenolics from Semen Astragali Complanati was undertaken. The optimised extraction condition with an orthogonal experiment design of L9(3(4)) was 50°C, 30min and 15:1 (methanol solution:sample, mL:g). An extraction yield of 40.12±1.10mg gallic acid/g dry seed and the antioxidant capacity of 0.85±0.13mg dry extract/mg DPPH were obtained with the optimum condition, respectively. For each extraction set, the antioxidant capacity by 2,2-diphenyl-1-picrylhydrazyl radical assay highly correlated to its total phenolic content by Folin-Ciocalteu method. Twelve phenolic components obtained with the optimised extraction procedure were tentatively identified by Ultra Performance Liquid Chromatography coupled with Q-TOF Mass Spectrometer (UPLC-Q-TOF) according to their mass spectrometry, UV/vis spectrometry, and related literature reports. Furthermore, the ultrasonic effect on the particles' microstructure of Semen Astragali Complanati was also investigated by scanning electron microscopy (SEM) analysis.