We investigated the estrogenic and breast cancer inhibitory activities of chemical constituents isolated from Rhei undulati Rhizoma (roots of Rheum undulatum L.), which is used as a laxative, an anti-inflammatory, and an anti-blood stagnation agent. Estrogen-like activity was studied using the well characterized E-screen assay in estrogen receptor (ER)-positive MCF-7 cells. The mechanism underlying the breast cancer inhibitory activity of the compounds was studied using human ER-negative MDA-MB-231 and ER-positive MCF-7 cells. The activation of apoptosis pathway-related proteins was investigated by western blotting, using extracts of R. undulatum prepared in three solvent conditions (EX1, EX2, and EX3). The R. undulatum chemical constituents (compounds 1–3) showed estrogen-like activity in the concentration range of 10 to 50 µM, by increasing the proliferation of human ER-positive MCF-7 cells. These effects were attenuated by co-treatment with 100 nM fulvestrant, an ER antagonist. Compounds 1–3 decreased the viability of MCF-7 cells in a concentration-dependent manner. Compounds 1 (aloe emodin) and 2 (rhapontigenin) induced mitochondria-independent apoptosis by activating the caspase-8 pathway, whereas the cytotoxic effect of compound 3 (chrysophanol 1-O-β-D-glucopyranoside) was mediated through the mitochondria-dependent apoptotic pathway.
Bibliographical noteFunding Information:
Funding: This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017R1A2B2011807), and Basic Science Research Program for Young Researchers funded by the Richwood Pharmaceutical Company, Republic of Korea.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Chemistry (miscellaneous)
- Molecular Medicine
- Pharmaceutical Science
- Drug Discovery
- Physical and Theoretical Chemistry
- Organic Chemistry