Antidepressant-like effects of the fractions of Xiaoyaosan on rat model of chronic unpredictable mild stress.

ETHNOPHARMACOLOGICAL RELEVANCE Xiaoyaosan (XYS), composed of Radix Bupleuri, Radix Angelicae Sinensis, Radix Paeoniae Alba, Rhizoma Atractylodis Macrocephalae, Poria, Herba Menthae, Rhizoma Zingiberis Recens and Radix Glycyrrhizae, is a valuable traditional Chinese medicine (TCM) which is used for the treatment of depression in China. In the formula, Radix Bupleuri usually serves as the principal drug, Radix Angelicae Sinensis and Radix Paeoniae Alba serve as the ministerial drugs, Rhizoma Atractylodis Macrocephalae, Poria, Herba Menthae and Rhizoma Zingiberis Recens serve as adjunctive drugs, Radix Glycyrrhizae serves as messenger drug, they coordinate with each other and enhance the effect of the formula. In our previous experiments, the antidepressant effect of XYS was revealed. However, the antidepressant part (or component) of this prescription was still obscure. We divided the XYS into five different polar fractions, and explored the antidepressant activity of five different polar fractions to identify the active fraction. MATERIALS AND METHODS Behavior research and metabonomics method based on (1)H NMR were used for efficacy study of different fractions in chronic unpredictable mild stress (CUMS) model of depression. Rats were divided into 8 groups and drugs were administered during the 21 days model building period. The urine samples of rats were collected overnight (12h) on 21 day and the metabolic profiling of the urine was measured using NMR. Multivariate analysis was also utilized to evaluate the active fraction of XYS. RESULTS In the behavior research, there were significant difference between the lipophilic fraction group (XY-A) and the model group. In addition, with pattern recognition analysis of urinary metabolites, the results showed a clear separation of the model group and control group, while XY-A group was much closer to the control group in the OSC-PLS score plot. Seven endogenous metabolites contributing to the separation of the model group and control group were detected, while XY-A group regulated the 5 perturbed metabolites showing a tendency of recovering to control group. CONCLUSIONS The present work suggested that petroleum ether fraction was the most effective fraction, implying that lipophilic components contribute to the antidepressant effect of XYS.