Herbal medicine pair, composed of two single herbs, is a relatively fixed minimum prescription unit in the traditional Chinese medicine's formula and has special significance in clinic. The combination of Xiangfu (the rhizoma of Cyperus rotundus L, XF) and Chuanxiong (the rhizoma of Ligusticum chuanxiong Hort, CX) has been recoded as an herbal medicine pair XF-CX in the Yuan Dynasty (1347 CE) of China and widely used in traditional Chinese medicine formula, including Chaihu Shugan San, which has been clinically used for treatment of depression. However, the optimal ratio of the XF-CX herbal medicine pair and its antidepressant constituents are still unclear. Herein, the antidepressive-like effects of XF-CX herbal medicine pairs with different ratios of XF and CX (2:1, 1:1, 1:2) were evaluated using behavioral despair animal models in mice, and then its potential antidepressant constituents were recognized by spectrum-effect relationship analyses. Finally, the potential antidepressant constituents of the XF-CX herbal medicine pair were validated by molecular docking with glucocorticoid receptor and corticosterone (CORT)-induced PC12 cell injury model. The results indicated that different ratios of XF-CX pairs had antidepressive-like effects, and the XF-CX (2:1) exhibited a more significant effect. Thirty-two potential antidepressant constituents in the XF-CX herbal medicine pair were screened out from the spectrum-effect relationship combined molecular docking analyses. Among them, senkyunolide A, cyperotundone, Z-ligustilide, and levistilide A were validated to have protective effects against CORT-induced injury in PC12 cells. Our findings not only obtained the optimal ratio of XF-CX in the herbal medicine pair for the treatment of depression but also its potential antidepressant constituents, which will benefit in elucidating the mechanism of action and promoting the application of the herbal medicine pair in the clinic.
