Inhibitory Effect of Rhei Rhizoma Constituents on the Cortisol Production in ACTH-Stimulated Bovine Adrenal Fasciculata Cells

Abstract

Depression can be activated by dysfunction of the hypothalamus–pituitary–adrenal (HPA) axis and is sometimes accompanied by increased cortisol production. In this study, the effects of Kampo extract products on cortisol production in bovine adrenal fasciculata cells via adrenocorticotropic hormone (ACTH) stimulation were investigated with the aim of identifying substances that can improve the function of the HPA axis. Daiokanzoto extract product, which is prepared from Rhei Rhizoma and Glycyrrhizae Radix as the constituent crude drugs, was found to potently inhibit cortisol production in bovine adrenal fasciculata cells. Because only Rhei Rhizoma decoction showed potent inhibitory effect, the cortisol production inhibitory substances in Rhei Rhizoma was analyzed. As a result, six anthraquinones: chrysophanol, emodin, aloe-emodin, rhein, chrysophanol-8-O-β-D-glucopyranoside, and physicion-8-O-β-D-glucopyranoside were isolated and identified from Rhei Rhizoma decoction. Among these compounds, emodin showed the strongest inhibition of the ACTH-induced cortisol production in cells (IC50 = 13.1 ± 1.9 µM). These results suggest that emodin may help of stress-induced illnesses such as depression.