Anti-estrogenic Constituents from Medicinal Plants

Estrogen regulates various physiological responses in many target tissues and plays an important role in the development and the progression of breast and endometrial cancers. Estrogen exerts its biological effects by binding to estrogen receptors (ER), which mainly exists in the nucleus as transcription factors, named ERα and ERβ. Estrogen-bound ERs dimerize and function as transcription factors which bind to a specific DNA sequence named the estrogen response element (ERE) present in the promoter or enhancer regions of target genes or ER interacted with other transcription factors. Selective estrogen receptor modulators (SERMs) bound ER and exerted estrogen agonist action in some target tissues while acting as estrogen antagonists in others. The physiological ligand for progesterone receptor (PR) is progesterone (P4), which is also critical in mammary gland development in the reproductive tract. PR has two predominant isoforms, PR-A and PR-B. PR-B mediates the proliferative effects of P4 in the mammary gland and PR-A is essential for the functional response of P4 in the uterus and ovaries. Therefore, it was suggested that the regulators of PR or ER are used for the prevention and treatment of breast cancer and postmenopausal osteoporosis.

The present study aimed to discover anti-estrogenic compounds from medicinal plants and explore the anti-estrogenic activity of its extracts or individual compounds using MCF-7 BOS cell proliferation assay, ERE-luciferase reporter gene assay, human estrogen receptor (hER), human progesterone receptor (hPR) binding assay, and in vivo uterotrophic assay.