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1991[X]
1Author    DonaldE M Oreland, FrederickT. CorbinRequires cookie*
 Title    Influence of Safeners on the in vivo and in vitro Metabolism of Bentazon and Metolachlor by Grain Sorghum Shoots: a Preliminary Report  
 Abstract    Metabolism of bentazon and m etolachlor by excised shoots and a microsomal fraction iso­ lated from the shoots, of 3-day-old, dark-grown, grain sorghum (Sorghum bicolor cv. Funk G 522 DR) seedlings was studied. The effects of seed treatments, on the subsequent m etabo­ lism of the herbicides, with the safeners naphthalic anhydride, oxabetrinil, and CGA 133205 were compared against surface-sterilization and Captan-treatm ents. Bentazon was aryl hydroxylated in both in vivo and in vitro studies with the hydroxylated derivative undergoing glycosylation only under in vivo conditions. Both shoots and microsomes isolated from shoots of safener-treated seed showed enhanced metabolism of bentazon relative to the controls. In­ hibition by tetcyclacis, a potent inhibitor of plant cytochrome P-450 monooxygenases, in both the in vivo and in vitro studies, and a requirement for N A DPH in the in vitro studies suggested that the formation of hydroxybentazon was mediated by a cytochrome P-450 monooxygenase. Metolachlor was metabolized to polar material and O-desmethylmetolachlor under in vivo conditions. Only the demethylated product was formed in vitro. Shoots isolated from safener-treated seed showed enhanced form ation o f polar com pounds which were assumed to have arisen from conjugation with glutathione. Tetcyclacis did not affect the formation of the polar components. However, the form ation of O-desmethylmetolachlor was depressed in the shoots excised from safener-treated seed under both in vivo and in vitro conditions. Tetcyclacis com ­ pletely prevented form ation of the demethylated metabolite. Hence, formation of this m eta­ bolite is considered to be P-450 mediated. The differential response obtained with the safeners, i.e., stimulation of aryl hydroxylation o f bentazon and depression of metolachlor demethyla-tion, suggests that the reactions are probably catalyzed by different cytochrome P-450 m ono­ oxygenases. 
  Reference    Z. Naturforsch. 46c, 906—914 (1991); received M arch 26 1991 
  Published    1991 
  Keywords    Microsomes, Metolachlor, Bentazon, Cytochrome P-450, Mixed Function Oxidase 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0906.pdf 
 Identifier    ZNC-1991-46c-0906 
 Volume    46