ARS | Publication request: Estrogenic and antiestrogenic activities of phytoalexins from red kidney bean (Phaseolus vulgaris L.)

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2010
Publication Date: February 15, 2011
Citation: Boue, S.M., Burow, M.E., Wiese, T.E., Shih, B.Y., Elliott, S., Carter Wientjes, C.H., Mclachlan, J.A., Bhatnagar, D. 2011. Estrogenic and antiestrogenic activities of phytoalexins from red kidney bean (Phaseolus vulgaris L.). Journal of Agricultural and Food Chemistry. 59:112-120.

Interpretive Summary: Legume phytoalexins (induced isoflavones) are produced under conditions of stress that include insect damage, wounding, or application of elicitors. The estrogenic and anti-estrogenic activities of methanolic extracts obtained from red kidney bean treated with the fungus Aspergillus sojae were compared with untreated controls using several assays for estrogenic activity. A. sojae-treated red kidney bean extracts displayed both estrogenic and antiestrogenic activities. The phytoalexins kievitone and phaseollin were isolated from A. sojae treated red kidney bean extracts. Both kievitone and phaseollin binded with estrogen receptors (alpha and beta). Both kievitone and phaseollin stimulated breast cancer cell growth and both inhibited the cell growth of cancer cells in an MCF-7 cell colonial survival assay. This work provides evidence that the red kidney bean phytoalexins kievitone and phaseollin possess both estrogenic and anti-estrogenic activities.

Technical Abstract: Legumes are the predominant source of isoflavones that are considered phytoestrogens that mimic the hormone 17B-estradiol (E2). Due to the risks associated with hormone replacement therapy there is a growing need for alternative sources of estrogenic formulations for the treatment of menopausal symptoms. Legume phytoalexins (induced isoflavones) are produced under conditions of stress that include insect damage, wounding, or application of elicitors. The estrogenic and antiestrogenic activities of methanolic extracts obtained from red kidney bean treated with the fungus Aspergillus sojae were compared with untreated controls using an estrogen responsive element-based (ERE) luciferase reporter assay. A. sojae-treated red kidney bean extracts displayed both estrogenic and antiestrogenic activities. Analysis of elicitor-treated red kidney bean extracts showed that A. sojae treatments achieved maximal levels of kievitone at 1199 plu or minus 101 µg/g and phaseollin at 227.8 plus or minus 44 µg/g. The phytoalexins kievitone and phaseollin were isolated from A. sojae treated red kidney bean extracts, and analyzed for estrogenic activity using ERx and ERB binding, ERE luciferase assays in MCF-7 and HEK 293 cells, and MCF-7 cell proliferation. Kievitone showed the highest relative binding affinity to ERx with kievitone (0.48%) > phaseollin (0.21%), and phaseollin showed the highest relative binding affinity to ERB with phaseollin (0.53%) > kievitone (0.42%). In a ERE luciferase assay in MCF-7 cells, kievitone displayed high ER transactivation at 10 µM; phaseollin displayed low ER transactivation. Both kievitone and phaseollin stimulated MCF-7 cell proliferation with kievitone displaying agonist activity between.