MA6 Environmental Chemistry and Toxicology of Chiral Pollutants
202 Oregon Ballroom
8:00 AM - 12:00 PM, Monday
() Enantiomer-specific effects of chiral pollutants.
Garrison, A1, Ekman, D1, Kenneke, J1, Mazur, C1, 1 U.S. Environmental Protection Agency, Athens, GA, USA
ABSTRACT- Enantiomers, the mirror image isomers of chiral pollutants, are known to be selective in their interaction with other chiral molecules, including enzymes and other biochemicals. Considerable research has shown, for example, that chiral pesticides are degraded selectively by microbes, leading to differential environmental persistence of the enantiomers. Enantioselectivity is also often observed in the residues of chiral pesticides and PCBs in animal tissues; the residues of several chiral PCBs in various tissues of rats injected with Aroclor 1254 were enantioselective. But, outside the pharmaceutical area, there has been little research on the effects of separate enantiomers. To distinguish these effects, it is necessary to use separate enantiomers, in our case separated by preparative HPLC. Measurements of endocrine disruptor (ED) activity of the enantiomers of several pesticides separated in this way have shown significant selectivity. Currently, we are measuring the toxicological selectivity of the enantiomers of vinclozolin, fipronil and other pesticides toward the luminescent bacterium V.fisheri using the Microtox assay system. In addition, vinclozolin and its enantiomers are being exposed to the Japanese medaka fish, after which the fish liver microsomal material is being assayed for cytochrome P450 activity. There will be corresponding assays using medaka DNA microarrays for indications of gene expression, and metabonomic measurements using high resolution NMR that will allow us to observe changes in the endogenous metabolites in the livers after exposure of the fish to vinclozolin and its enantiomers. Another project involves measurement of the enantioselectivity of certain conazoles, members of an important class of azole fungicides, upon reaction with the cytochrome P450 enzymes of rat microsomal material. Preliminary chromatographic analysis indicates enantioselectivity in the conazole reactivity. This abstract has been reviewed in accordance with the U.S. Environmental Protection Agency peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
Key words: chiral pollutants, enantiomers , enantioselective effects, cytochrome P450