Phytoestrogen kaempferol (3,4',5,7-tetrahydroxyflavone) protects PC12 and T47D cells from beta-amyloid-induced toxicity.

In clinical studies, it has been shown that estrogen replacement therapy in menopause is strongly correlated with a reduced risk of the development of Alzheimer's disease (AD). In in vitro experiments, it was demonstrated that estradiol protects cells against the toxic effects of beta-amyloid, the major component of plaques in brains of AD patients. Therefore, estrogens have become interesting candidates for a possible treatment of neurodegeneration. In plants, a class of compounds has been identified that bind to human estrogen receptor, so-called phytoestrogens, which are part of our daily diet. Here, we compared the effects of alpha- and beta-estradiol with plant-derived kaempferol on beta-amyloid peptide-induced toxicity in PC12 neuroblastoma and T47D human breast cancer cells. The present results demonstrate a protective effect of kaempferol comparable to that observed with estradiol. The effects of the weak estrogen receptor agonists alpha-estradiol and kaempferol were found to be similar to the effects of the strong estrogen receptor agonist beta-estradiol, suggesting a mode of action independent from the nuclear estrogen receptor.