Xenobiotic conjugation higher plants

Isomerization of an S-cystelne conjugate to an -cysteine conjugate via the Smiles rearrangement has been observed In the metabolism of two trlazlne xenobiotics In higher plants atrazlne metabolism In sorghum (103,W ) 8 dlmethametryn metabolism In rice (J05). This nonenzymatic rearrangement (Equation 26) has not... 

The metabolism of xenobiotics in higher plants has been studied extensively over the last 20 years. In common plant species such as corn, it is frequently possible to predict the conjugation reactions that may be utilized in the initial phases of metabolism of a new xenobiotic. In less commonly studied species, predictions are more uncertain and exotic metabolites sire occaslonaly formed. In those cases where phase I oxidative reactions are likely, it is difficult to predict the course of metabolism because phase I oxidation reactions in plants are frequently very substrate and species specific. Phase I oxidative reactions have a profound effect on ensuing conjugation reactlcxis. The presence of multiple functional groups on a xenobiotic also Increases the uncertainty of the route of metabolism likely to be followed in a particular species. 

LAMOUREUX AND RUSNESS Xenobiotic Conjugation in Higher Plants... 

The conjugation of xenobiotics with glutathione (GSH) in higher plants was first demtxistrated to be a major enzymatic detoxication mechanism with the atrazine herbicide in sorghum, corn, and other atrazine resistant species (77-80) (Equation 15). Since this... 

Xenobiotic GSH conjugates are metabolically unstable in higher plants and rapidly undergo additional enzymatic and/or nonenzymatic transformations to a variety of products by processes that have been reviewed recently (15,26, ). With several exceptions, the primary routes of metabolism of GSH conjugates in plants are similar to those observed in mammals as discussed by Baldce in Chapter I6. In sorghum and corn, the first step in the catabolism of a xenobiotic... 

Acetylated xenobiotic conjugates are not commonly formed In higher plants however, the direct or Indirect conjugation of xenoblotlca... 

Xenobiotics that contain a free or potential carboxyl group can be metabolized by amino acid conjugation in both plants and animals. This reaction is illustrated by the conjugation of 2,4-D with aspartic acid (Equation 31). In higher plants, amino acid conjugation is... 

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