Xiaoyao San against depression via glia-mediated neuroinflammation using network pharmacology and experimental validation

Xiaoyao San (XYS) has been proven effective in treating depression, but its underlying mechanisms remain to be elucidated. This study aims to explore the key phytochemicals and mechanisms of the anti-depressant effects of XYS. We focus on the 16 blood compounds of XYS identified through the UPLC-MS/MS method. We also validated the results of the network pharmacology analysis using an lipopolysaccharide (LPS)-induced depression mouse model and the BV2 microglial cell line. In silico prediction, atractylenolide I, ferulic acid, kaempferol, quercetin, and vanillic acid exhibit good oral bioavailability, safety, and ADMET properties. The results of GSEA and GO enrichment analysis showed that neuroinflammation is the key mechanism of the anti-depressant effect of XYS. Kaempferol, quercetin, atractylenolide II, z-ligustilide, paeoniflorin, saikosaponin A, atractylenolide III and glycyrrhizic acid (GA) were identified as the main phytochemicals targeting neuroinflammation. XYS gavage treatment significantly ameliorated LPS-induced depressive-like behaviors in mice by reducing neuroinflammation (microglial activation) in the prefrontal cortex. The reduction of LPS-induced pro-inflammatory cytokine levels by GA was also validated in BV2 cells, and its mechanism is associated with JNK pathway. The phytochemicals of XYS exhibit favorable safety and pharmacological parameters, with targeting neuroinflammation being the key mechanism underlying its anti-depressant effects.