Danggui Buxue Tang (DBT; 當歸補血湯), a herbal decoction that is composed of Astragali Radix (AR; Huangqi, 黃芪) and Angelica Sinensis Radix (ASR; Danggui, 當歸), has been used for treating menopausal irregularity in women for more than 800 years in China. Among thousands of traditional Chinese medicine (TCM) herbal formulae, most of them consist of multiple herbs, while DBT is considered to be the simplest decoction. Here, we chose DBT as an example to explain the TCM theory by using chemical and biological assessment....[ Read more ]

Danggui Buxue Tang (DBT; 當歸補血湯), a herbal decoction that is composed of Astragali Radix (AR; Huangqi, 黃芪) and Angelica Sinensis Radix (ASR; Danggui, 當歸), has been used for treating menopausal irregularity in women for more than 800 years in China. Among thousands of traditional Chinese medicine (TCM) herbal formulae, most of them consist of multiple herbs, while DBT is considered to be the simplest decoction. Here, we chose DBT as an example to explain the TCM theory by using chemical and biological assessment.

According to the traditional record of DBT preparation, ASR had to be processed by yellow wine before usage, which markedly increased the efficacy of ASR, as well as enhanced the bioactivities of DBT. However, the underlying mechanism of the wine-processing is unknown. Here, the level of ligustilide, a volatile oil, could be reduced by wine-processing, while the level of ferulic acid could be increased by wine-processing. The evidence suggested that ligustilide and ferulic acid could be the critical regulators of DBT. After chemical and biological evaluations, ligustilide and ferulic acid had been demonstrated to be a negative regulator and a positive regulator of DBT, respectively. The current results strongly supported the traditional practice of preparing DBT by using the wine-processed ASR.

To reveal the mechanism of DBT-induced erythropoietin (EPO) expression, the upstream regulator of this gene was revealed in cultured human embryonic kidney fibroblasts (HEK293T). The plasmid containing hypoxia response element (HRE), when being transfected into fibroblasts, was highly responsive to the challenge of DBT. To account for the transcriptional activation of HRE, DBT treatment was shown to increase the expression of mRNA and protein of hypoxia-inducible factor-1 (HIF-1α), as well as the blockage of the degradation pathway of HIF-1α protein. In addition, the activation of a mitogen-activated protein kinase (MAPK)-dependent signaling by DBT could also enhance the translation of HIF-1α mRNA, suggesting the multiple actions of DBT in stimulating the EPO expression. Furthermore, AR-derived flavonoids, including formononetin, ononin, calycosin and calycosin-7-O-β-D-glucoside, had been demonstrated to be the major active ingredients for the erythropoietic effect of DBT. Taken together, the current results revealed the molecular mechanism of this ancient herbal decoction in enhancing the erythropoietic functions.

In order to demonstrate synergistic effects of AR and ASR during the chemical absorption, the absorption across human epithelial colorectal adenocarcinoma (Caco-2) cell monolayers of AR-derived astragaloside IV, calycosin, formononetin, and ASR-derived ferulic acid, ligustilide were determined by triple quadrupole tandem mass spectrometer (QQQ-MS/MS). The pharmacokinetic results showed that the membrane permeability of calycosin and formononetin, which are considered as moderate permeable compounds, could be markedly increased in the presence of ASR extract. The results suggested that the possibility of herb-herb interactions in a synergistic manner, which supports that the necessity of co-existence of AR and ASR during the preparation of DBT.

Our results, in agreement with the previous studies, strongly support the preparation and biological efficacy of DBT: (i) the traditional preparation of DBT was proved to be reasonable, including the composition of AR and ASR, and the wine-processing of ASR, which should be complied nowadays; (ii) the elucidation of biochemical mechanism of “Blood” nourishing could establish a scientific for the use of DBT. Taken together with the current and previous studies on DBT, we have been able to integrated develop a systematic approach for investigating TCM formulae through chemical and biological assessments.