Preliminary study on metabolism of pyribambenz-propyl by wheat microsomes

Microsomes were prepared from etiolated wheat seedlings pretreated with 5% (v/v) ethanol and 10mmol/L Pyribambenz-propyl for 24h at 25 degree C in a dark and reacted with [C ring-U-14C] pyribambenz-propyl). Radioactive labeled compounds were extracted from the reaction solution with ethyl acetate, separated and determined by HPLC-LSC, and then identified by HPLC-MS (ESI). Three major metabolites (Y1, Y2 and Y3), presumably related to Smiles rearrangement, indicated that Pyribambenz-propyl underwent hydroxylation in wheat microsomes and the in vitro system might also facilitate isomerization of Pyribambenz-propyl. Further studies are required to clarify whether rearrangement reactions of Pyribambenz-propyl is ready to occur within plant cells and whether these Smiles rearrangement-related metabolites are involved in herbicidal activities and/or detoxification of the (pro-) herbicide. (authors)