The immature fruit of Citrus aurantium L. (Zhi-Qiao, ZQ) has been used as a traditional medicine in China. Our previous study has shown that ZQ decoction may contribute to the antidepressant-like action of Chaihu-Shu-Gan-San. However, there are no reports on the chemical constituents of ZQ aqueous extract or its anti-depression effects. Firstly, this research reported the on-line identification of the chemical constituents in the aqueous extract of ZQ by coupling ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC-Q-TOF/MS). A total of 31 chemical constituents were identified in ZQ aqueous extract, including one tannic acid, five flavones, 13 flavanones, one limonoid, three coumarins, three cyclic peptides, and five polymethoxylated flavonoids. The antidepressant effect of ZQ aqueous extract was evaluated in vivo and the results indicated that the mice immobility time during the forced swimming test and the tail suspension test were significantly reduced with ZQ treatment. MTT assays showed both ZQ aqueous extract and its major constituents (naringin, hesperidin, neohesperidin, and nobiletin) had neuroprotective effect on corticosterone-induced neurotoxicity in PC12 cells. The in vivo and in vitro results suggest that ZQ has an antidepressant effect.

Cyperi Rhizoma (CR) is a well-known functional food and traditional herbal medicine in Asian countries for the treatment of menstrual or emotional disturbances in women. Recent studies have shown the pharmacological effects of CR on neuronal diseases, such as Parkinson’s disease (PD) and depression. Thus, the neuroprotective effect of CR might play a vital role in exerting its effect. Here, corticosterone-induced PC12 cells were applied to screen the active fraction of CR and evaluate its neuroprotective effect. The results indicated that the fraction containing medium-polarity chemical constituents (CR-50E) displayed the best protection effect. CR-50E could increase the cell viability and reduce cell apoptosis through inhibiting oxidative stress and decreasing the lactate dehydrogenase LDH release induced by corticosterone. Further, the mechanism of action was explored by cell metabolomics. The result showed CR-50E mediated the sphingolipids metabolism of corticosterone-induced PC12 cells, which suggested inhibition of Ca²⁺ overloading may involve the protection of CR-50E against cell damage. The expression levels of three key proteins in calcium transport, including phospholipase A2 (PLA2), calcium/calmodulin independent protein kinase II (CaMK II), and caspase-3, confirmed the above result by Western blot. The findings suggest that CR-50E can suppress the disequilibrium of calcium homeostasis-mediated apoptosis by improving the abnormal sphingolipids metabolism as well as remedying the damage of the cell membrane.