Uptake and degradation of natural and synthetic estrogens by maize seedlings

Abstract

Runoff from manure-fertilized crop fields constitutes a significant source of natural estrogens (e.g., estradiol [E2] and estrone [E1]) and synthetic estrogen mimics (e.g., zeranol [α-ZAL] and zearalanone [ZAN]) in the environment. However, processes such as sorption to and uptake by plants may inhibit the environmental mobility of hormonally-active compounds. To evaluate the role of plants in the environmental fate of such compounds, we exposed maize seedlings to hydroponic solutions containing E2, E1, α-ZAL, and ZAN. After 12 days of exposure, ZAN concentrations decreased by 78%, E1 and α-ZAL decreased 99.9%, and E2 was undetectable. Exposure to seedlings resulted in both oxidation (i.e., transformations of E2 to E1 and α-ZAL to ZAN) and reduction reactions (i.e., E1 to E2 and ZAN to α-ZAL). Although the oxidation of E2 and α-ZAL may be attributed to plant-associated microbes, the reduction of E1 and ZAN is unlikely to be microbially-mediated.