Abstract: Objective To establish a method for evaluating the biological activity of water soluble extracts of Radix Glycyrrhizae based on a macrophage phagocytosis model. Methods Aquatic extracts of Radix Glycyrrhizae were provided by China National Traditional Chinese Medicine Co., Ltd. with the batch numbers of GCGSQ, GCGSC, GCNMG and GCXJ, and GSGSC is used as a verification batch. The optimized experimental conditions were investigated. The seeding density of cells, LPS concentration, action duration, drug concentration-response curves were determined by CCK-8 assay. The phagocytosis indexes of RAW 264.7 macrophages were determined by neutral red uptake assay and repeated at least 5 times to set the dose limit. Results The optimum cell density was chosen to be 3.0×10⁵/mL and 100μL was seeded in 96-well plates, the drug action time was 24h and LPS concentration was 0.25μg/mL, which obtained more stable effects. The aquatic extracts of Radix Glycyrrhizae stimulated proliferation and phagocytic activity in RAW264.7 in a concentration-dependent manner when the concentrations ranged from 125 to 500μg/mL. At the concentration of 125μg/mL, better activity with good precision (RSD=0.9%) and repeatability (RSD=2.15%) was observed in the extracts of bathes of GCGSQ, GCGSC, GCXJ. Under this experimental condition, the concentration of 125 μg/mL was selected as the dose limit, and the phagocytosis indexes of macrophages that ranged from 115% to 129% were set as the bioassay quality control supplement. Conclusion Combined with clinical indications, the effects of Radix Glycyrrhizae on phagocytic activity in RAW264.7 macrophages might be used as an indicator for bioassay as the supplementary quality control.

Key words: water soluble extracts of Radix Glycyrrhizae, RAW264.7, phagocytosis, biological evaluation, macrophage, quality control