Reactions of 17β-Estradiol Mediated by Lignin Peroxidase: Phase Distribution of Products.

We have demonstrated in a recent study that a few natural and synthetic estrogens can be effectively transformed through reactions that are mediated by lignin peroxidase (LiP), and the behaviors of such reactions are variously influenced by the presence of natural organic matter (NOM) and/or veratryl alcohol (VA). Certain white rot fungi, e.g. Phanerochaete chrysosporium, produce VA as a secondary metabolite along with LiP in natural environments where NOM is ubiquitously present. In this presentation, we will introduce a systematic investigation on the products of 17β-estradiol (E2), as a model estrogen, resulting from LiP-mediated oxidative coupling reactions, and in particular, how the presence of NOM and/or VA impacts the product distribution. A total of six products of E2 reactions were identified using HPLC in combination with MS/MS techniques. We found that the products are oligomers resulting from E2 coupling and seem to form the solid phase in water that can be removed by filtration with 0.45µm filter. When VA was present in the reaction system, the product distribution was found varied towards higher degree of oligomers , and an additional product resulting from cross-coupling between estrone (E1) and E2 was identified. When NOM was included in the reaction system, we found evidence indicating cross-coupling between E2 and NOM. Apparently such reactions will significantly impact estrogen transport and bioavailability in the environment.