Optimization of Extraction Process by Response Surface Methodology, Composition Analysis and Antioxidant Activity of Total Flavonoids from Scutellaria baicalensis Georgi

In order to further enhance the extraction yield of total flavonoids from <i>Scutellaria baicalensis</i> Georgi, the extraction process was optimized, and its composition and antioxidant activity were also analyzed. Through single-factor and response surface methodology optimization, the optimal extraction process of total flavonoids from <i>S. baicalensis</i> was obtained as follows: 56% ethanol concentration, 40:1 (mL/g) ratio of liquid to solid, 50 °C extraction temperature, and 1 h of extraction time. Under the optimal extraction conditions, the total flavonoid yield reached was 165.40 mg/g, which was 70.16% higher than the blank group and 89.68% higher than previously reported results. The major composition of total flavonoids was analyzed using UHPLC-MS/MS. A total of 60 flavonoid compounds were identified, of which 20 flavonoids had not been reported previously. The in vitro antioxidant activity of the total flavonoids was analyzed by DPPH and ABTs assays. IC₅₀ of the total flavonoids on DPPH and ABTs free radicals were 0.52 μg/mL and 0.66 μg/mL, respectively, which indicated that the total flavonoids of <i>S. baicalensis</i> had a remarkable free radical scavenging ability. This study should provide theoretical and technical support for the industrial production and bioactivity-oriented utilization of flavonoids from <i>S. baicalensis</i>.