Cytochrome P450-Dependent Hydroxylation of Prosulfuron (CGA 152005) by Wheat Seedling Microsomes

Abstract

Microsomes isolated from shoot tissues of etiolated wheat seedlings (Triticum aestivum L. var. Olaf) oxidized the sulfonylurea herbicide prosulfuron (CGA 152005). One major and two minor enzymatic oxidation products were isolated and identified by negative ion FAB/MS and cochromatography (TLC and HPLC) with reference standards. Identification of the major oxidation product (I) as 1-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-3-[2-(3,3,3-trifluoropropyl)-5-hydroxyphenylsulfonyl]urea was confirmed by proton NMR spectroscopy. Minor oxidation products were tentatively identified as 1-[4-(hydroxymethyl)-6-methoxy-1,3,5-triazin-2-yl]-3-[2-(3,3,3-trifluoropropyl)phenylsulfonyl]urea (II) and an intermediate oxidation product 1-[4-[(hydroxymethyl)oxy]-6-methyl]-1,3,5-triazin-2-yl]-3-[2-(3,3,3-trifluoropropyl)phenylsulfonyl]urea (III) that degraded to 1-(4-hydroxy-6-methyl-1,3,5-triazin-2-yl)-3-[2-(3,3,3-trifluoropropyl)phenylsulfonyl]urea (IV). Microsomal oxidation of prosulfuron required NADPH and molecular oxygen. C...