Poster: Secondary Metabolism

Abs # 298: Isolation, chemical and biological characterization of mulberry phytoestrogens

Presenter:	Maier, Camelia G.-A., cmaier@twu.edu
Authors	Maier, Camelia G.-A. (A)   Ivette, Guzman  (A)
Affiliations:	(A): Texas Woman's University, Department of Biology

Phytoestrogens are natural components of plants, which have similar structures to mammalian estrogens. Estrogenic activities of extracts from female mulberry, Morus alba (Moraceae) were found to be significantly higher than those of male extracts in a transgenic yeast system expressing the human estrogen receptor alpha (hERa) (Maier et al., 1995, 1997). The objectives of this study were to isolate and characterize phytoestrogens in mulberry in an effort to understand their functions in plants. It was expected that phytoestrogens in mulberry would be flavonoids. Solid phase extraction (SPE) was used to separate fractions of ethanol plant extracts on reversed phase C18 columns. Fraction 80 (F80) was separated by one-dimensional and bi-dimensional TLC on silica C18 plates. Diphenyl boric acid 2-amino-ethyl ester (D-boric) was used to identify flavonoids on TLC plates. SPE and TLC fractions were assayed for estrogenic activity using the transgenic yeast system expressing hERa. The highest estrogenic activity, 4% of estradiol activity, among all SPE fractions assayed in transgenic yeast was detected with F80. Migration of SPE F80 alongside the standards genistein and apigenin on TLC D-boric treated plates resulted in fluorescent spots indicating that mulberry phytoestrogens are flavonoids. One compound co-migrated along with apigenin, a flavone, on TLC, suggesting that at least one phytoestrogen in mulberry may be apigenin. Chemical characterization with SPE and TLC, and biological characterization using the transgenic yeast system, demonstrated the presence of flavonoid phytoestrogens in Morus alba. Characterization will continue with RP-HPLC. Supported by NIH GM55380 grant.