Comparative analysis of volatile components in the Bupleuri Radix and Cinnamomi Ramulus herb pair and their potential mechanism in depression treatment.Volatile constituents from the individual herbs (Bupleuri Radix,Cinnamomi Ramulus) and their herb pair were analyzed and compared using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS).Key components in the herb pair were identified based on relative peak area.Subsequently,an integrated approach combining bioinformatics analysis and experimental validation was employed to screen the critical targets and potential mechanisms underlying the antidepressant activity of these volatile components.The results demonstrated that 55,31,and 43 volatile compounds were identified in Bupleuri Radix,Cinnamomi Ramulus,and the herb pair,accounting for 93.02%,89.36%,and 96.87% of the total volatile content,respectively.The volatile profile was predominantly composed of terpenes and phenylpropanoids.Comparative analysis revealed substantial alterations in the levels of alkenes,aldehydes,and ethers in the herb pair compared to the individual herbs.Notably,new constituents such as 6,7-dihydroxycoumarin and β-bisabolene,which possess documented antidepressant potential,were detected in the herb pair.Conversely,the content of harmful components like 4-allylanisole,known for its genotoxicity and carcinogenicity,was significantly reduced.Principal component analysis further confirmed a distinct separation between the volatile profiles of the single herbs and the herb pair,with the herb pair exhibiting the highest composite score,indicating a rational and synergistic combination.Furthermore,integrated bioinformatic analysis and experimental validation revealed that the volatile constituents from the herb pair effectively suppressed the elevated expression of three core genes—cathepsin S (CTSS),3-hydroxy-3-methylglutaryl-coa reductase (HMGCR),and p65 subunit of NF-κB (RELA)—in the peripheral blood of depressed mice.Concurrently,treatment with these volatiles ameliorated depression-like behaviors in the mouse model.In conclusion,building upon the observed changes in volatile composition,the combination of Bupleuri Radix and Cinnamomi Ramulus demonstrates an effect of "reducing toxicity and enhancing efficacy".The volatile constituents from the herb pair effectively alleviate depressive-like behaviors in mice,potentially through a mechanism involving the modulation of core gene expression,which may indirectly influence associated inflammatory pathways.