Danggui
Buxue
Tang (DBT), a Chinese herbal decoction containing
Astragali
Radix (AR; roots of
Astragalus memebranaceus (Fisch.) Bunge var.
mongholicus (Bunge) Hsiao) and
Angelicae
Sinensis
Radix (ASR; roots of
Angelica sinensis Oliv.) at a weight ratio of 5:1, is used to improve menopausal syndromes in women. Several lines of evidence indicate that DBT has strong estrogenic property; however, the action mechanism of this herbal decoction is not known.
Calycosin, a major flavonoid in AR, shares similar structure with β-estradiol, and thus which is hypothesized to be the key compound of DBT in responsible for such estrogenic properties.
Aims
We aimed to determine the role of calycosin in DBT in terms of its estrogenic functions by the creation of calycosin-depleted DBT (DBTΔcal) and calycosin-added DBT (DBT+cal) herbal extracts.
Methods
The signalings triggered by DBT∆cal, DBT+cal, and parental DBT were compared in cultured MCF-7 cells by determining: (i) the activation of estrogen responsive element; (ii) the phosphorylation of estrogen receptor α (ERα); and (iii) the phosphorylation of Erk1/2. The DBT-induced responses were in dose- and/or time-dependent manners.
Results
The estrogenic signals triggered by DBT were markedly reduced in DBTΔcal, and in contrast the addition of calycosin in DBT, i.e. DBT+cal, enhanced the responses by 2–5 folds; however, calycosin alone did not show such properties. In parallel, the DBT-induced responses could be significantly blocked by inhibitors for estrogen receptor and mitogen activated protein kinases.
Conclusion
Thus, we hypothesize that calycosin is an indispensable chemical in DBT, and which plays a linker in orchestrating multi-components of DBT as to achieve the maximal estrogenic functions. These discoveries should be invaluable in drug development and in investigating the modernization of traditional Chinese medicine from a new perspective.
