Optimization of Extraction of Luteolin from Schisandra chinensis by Ionic Liquid–Enzyme Complex System and Antioxidant Study Analysis

Abstract

The luteolin in Schisandra chinensis [Schisandraceae Schisandra (Turcz.) Baill.] were extracted by ultrasonic extraction assisted by an ionic liquid–enzyme composite system, and the content of luteolins was determined using high-performance liquid chromatography (HPLC). This process was initially conducted through a one-factor experiment and a Box–Behnken combinatorial design of response surface method. The extraction process was optimized, and the results demonstrated that the optimal extraction conditions were 13.31% enzyme addition, 0.53 mol/L ionic liquid concentration, 173.47 min ultrasonic shaking, and 0.2266 mg/g, which was 4.88 times higher than that of the traditional reflux extraction. Secondly, the antioxidant function of luteolins was studied based on network pharmacology. For the study of the antioxidant mechanism of luteolin, the herb group identification database, SwissTargetPrediction on luteolins target prediction, and GeneCards database to achieve the antioxidant target were used. For the analysis of the intersection of the target protein interactions, GO bioanalysis and KEGG signaling pathway enrichment analysis were used. There were 57 overlapping targets of luteolin and antioxidants, including AKT1, MMP9, ESR1, EGFR, and SRC. GO function and KEGG pathway enrichment analysis showed that luteolin antioxidants were related to zoerythromycin metabolic process, adriamycin metabolic process, negative regulation of apoptotic process, endocrine resistance and oxidoreductase. The key targets in the pathways, such as luteolin AKT1 and MMP9, exert antioxidant effects. The antioxidant activity of luteolins was investigated by determining the scavenging ability of luteolins against two types of free radicals: 2,2-bipyridine-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS+) free radicals and 1,1-diphenyl-2-trinitrophenylhydrazine free radicals (DPPH-). The results of the antioxidant test demonstrated that the ABTS radical scavenging rate was 87.26%, and the DPPH radical scavenging rate was 93.85% when the quality concentration of Schisandra luteolins was 0.1 mg/g, indicating the potential of this natural antioxidant. This method of extracting Schisandra chinensis luteolins is highly productive, environmentally friendly, and practical, and it facilitates the development and utilization of industrial Schisandra chinensis.