Objective: To research the antioxidant activity of Chaihu Shugansan (CSGS) from different compatibility rules in vitro

further identify its antioxidant components and evaluate its regulation ability in the treatment of CSGS in depression. Method: After CSGS was divided into eight compatibility groups

their free radical scavenging activity was determined respectively by 1

1-diphenyl-2-picryl-hydrazyl (DPPH) method

with the mass concentration value at a clearance rate of 50%(IC50) as an evaluation index. Orthogonal partial least squares (OPLS) method was used to investigate the correlation between the characteristic peaks and the efficacy of CSGS

and subsequently the significant active ingredients were identified by the variable importance of projection (VIP) based on the high performance liquid chromatography (HPLC) characteristic chromatograms. SYBYL 2.0 software was used for molecular docking studies of the antioxidant components in CSGS and regulation of CSGS treatment on depression-related enzymes. Finally

the binding capacity of small molecules and macromolecules was determined on the basis of total score value. Result: The results demonstrated that the contribution order of eight herbs for antioxidant activity was as follows:Aurantii Fructus>Citri Reticulatae Pericarpium>Chuanxiong Rhizoma>Bupleuri Radix>Cyperi Rhizoma>Paeoniae Radix Alba>Glycyrrhizae Radix et Rhizoma. Besides

three ingredients including hesperidin

neohesperidin and narirutin were identified as the antioxidant activity components. Docking results of both antioxidant components in CSGS and the enzymes regulated by CSGS in the treatment of depression showed a good binding ability. Among them

the binding energy of hesperidin and tryptophanase (TPH)

neohesperidin and superoxide dismutase (SOD)

narirutin and tryptophan 2

3-dioxygenase (TPHD) was 9.088 7

8.734 0

9.271 8

respectively. Conclusion: Hesperidin

neohesperidin and narirutin might be the main effective components of CSGS for the antioxidant activity in vitro and they play a regulatory role in the CSGS treatment of depression.