Abstract
We purified phytoestrogens from Pueraria root (Pueraria mirifica from Thailand and Pueraria lobata from Korea), which is used as a rejuvenating folk medicine in Thailand and China. Dried, powdered plant material was extracted with 100% ethanol and further separated by concentration, filtration, and thin layer silica gel chromatography. Using the fractions obtained during separation, we first investigated their cytotoxicity in several cancer cell lines from various tissues. The ethanol-extracted components (PE1, PE4) had significant antiproliferative effects on breast cancer cell lines, including MCF-7, ZR-75-1, MDA-MB-231, SK-BR-3, and Hs578T. Second, we compared these results with the cytotoxic effects of known flavonoids, sterols, and coumarins from Pueraria root. The known compounds were not as effective, and occurred in a different polarity region on HPLC. Third, further separation resulted in the isolation of eight different components (Sub PE-A to -H). One of these, PE-D, affected the growth of some breast cancer cell lines (MCF-7, MDA- MB-231) in a dose- and time-dependent manner, as well as the growth of ovarian (2774) and cervical cancer cells (HeLa). Finally, a transfection assay showed that this component had an estrogenic effect similar to 17beta - estradiol, which activates both estrogen receptor alpha (ERalpha) and ERbeta. The NMR analysis determined that spinasterol (stigmasta-7, 22-dien-3beta-ol) is an active cytotoxic component of Pueraria root.
Highlights
Estrogen exerts a wide variety of effects on growth, development, differentiation, and reproduction
Estrogen mediates these activities via binding to a specific nuclear receptor protein, the estrogen receptor (ER), which is encoded by two genes (ERα and ERβ) that function as transcription factors to regulate the expression of target genes (Osborne et al, 2001)
We found that the profiles of the phytoestrogens extracted from the two Pueraria roots were similar, and demonstrated that Pueraria extract has antiproliferative effects on certain gynecological cancer cell lines, and acts on both ERs
Summary
Estrogen exerts a wide variety of effects on growth, development, differentiation, and reproduction (for review, see Nilsson et al, 2001). We found that the profiles of the phytoestrogens extracted from the two Pueraria roots were similar, and demonstrated that Pueraria extract has antiproliferative effects on certain gynecological cancer cell lines, and acts on both ERs. The active cytotoxic component in the final fraction appears to be spinasterol, an isomer of stigmasterol, which is one of the known phytoestrogens in Pueraria extract.
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