Ferulic acid enhances the chemical and biological properties of astragali radix: a stimulator for danggui buxue tang, an ancient Chinese herbal decoction.

Danggui buxue tang, an ancient formula composed of astragali radix and Angelicae sinensis radix, has been used for treating menopausal irregularity in women for more than 800 years in China. In danggui buxue tang, the complete functions of astragali radix require the assistance of Angelicae sinensis radix, and both herbs have to work harmoniously in order to achieve the maximal therapeutic purposes. In order to analyze the relationship of the two herbs, the role of ferulic acid, a major chemical within Angelicae sinensis radix, in chemical and biological properties of astragali radix was determined. Using ferulic acid in the extraction of astragali radix, the amounts of astragaloside IV, calycosin, and formononetin were increased in the final extract; however, the astragali radix polysaccharide showed a minor increase. The chemical-enriched astragali radix extract showed robust induction in osteogenic and estrogenic activities in cultured osteosarcoma MG-63 and breast MCF-7 cells. However, ferulic acid itself did not show such biological responses. The current results strongly suggest that Angelicae sinensis radix-derived ferulic acid is a positive regulator for danggui buxue tang, which enhanced the solubilities of active ingredients derived from astragali radix, and which therefore increased the biological efficacies of danggui buxue tang.