Extraction Optimization of Galla Turcica Polysaccharides and Determination of Its Antioxidant Activities In Vitro

Though natural polysaccharides commonly show antioxidant activities, the current research on the isolation of polysaccharides from Galla Turcica and their antioxidant activities still remain as an ongoing challenge. In this work, response surface analysis was employed to optimize an ultrasonic-assisted extraction method for polysaccharides of Galla Turcica. Their antioxidant and free radical scavenging activities were then evaluated using 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), total antioxidant activity, and iron ion reduction assays. Moreover, the protective effects of polysaccharides of Galla Turcica were determined on human embryonic kidney fibroblast 293 and hepatoma 7721 cells by cell proliferation assay. Overall, the key parameters of Galla Turcica polysaccharides extraction were optimized as crushing degree 100 mesh, ultrasonic time 50 min, and materials–liquid ratio 1:50. The isolated polysaccharides presented dose-dependent antioxidant and free radical scavenging effects in vitro. It also demonstrated an effective protective effect for human cells under oxidative damage. The results firstly determined the antioxidant activities of polysaccharides from Galla Turcica, thus providing a new natural resource for future investigation and development of the polysaccharides-based antioxidant drugs, health products, or additives.