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1996 (1)
1990 (1)
1Author    DonaldE. Moreland, FrederickT. Corbin, WilliamP. Novitzky, CarolE. Parker, KennethB. TomerRequires cookie*
 Title    Metabolism of Metolachlor by a Microsomal Fraction Isolated from Grain Sorghum ( Sorghum bicolor) Shoots  
 Abstract    A microsomal fraction isolated from the shoots of 3-to 4-day-old, dark-grown, grain sor­ ghum (Sorghum bicolor cv. Funk G 522 D R) seedlings was characterized. The preparations had a cytochrome P-450 content that varied from approximately 90 to 150 pmol P-450/mg protein with cytochrome P-420 varying from 0 to 3% of the P-450 content. Type I difference spectra were formed with cinnamic acid and metolachlor, and a type II spectrum was formed with tetcyclacis. In short-term assays with [14C]metolachlor as substrate, the preparations produced a single time-dependent product that separated on silica gel TLC plates developed in benzene/ acetone (2:1, v/v). R F values for metolachlor and the metabolite were approximately 0.70 and 0.48, respectively. The microsomal reaction required N A D PH and oxygen, and was inhibited by carbon monoxide, with the inhibition being partially reversed by actinic light. Compounds known to inhibit the activity of cytochrome P-450 monooxygenases (piperonyl butoxide, tet­ cyclacis, and tridiphane) also prevented formation of the metabolite. Identity of the metabolite was confirmed by TLC and positive ion thermospray LC/MS to be 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-hydroxy-l-methylethyl)acetamide. Hence, the reaction catalyzed by the sorghum microsomes involved O-demethylation of the methoxypropyl side chain of meto­ lachlor. 
  Reference    Z. Naturforsch. 45c, 558—564 (1990); received November 9 1989 
  Published    1990 
  Keywords    Microsomes, Metolachlor, Cytochrome P-450, Mixed Function Oxidase, Herbicide Metabolism 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0558.pdf 
 Identifier    ZNC-1990-45c-0558 
 Volume    45 
2Author    D. Onald, E. M. O Relan D, T. Hom, J. Fleischm, FrederickT C Orbina, JanisE M CfarlandbRequires cookie*
 Title    Differential Metabolism of the Sulfonylurea Herbicide Prosulfuron (CGA-152005) by Plant Microsomes  
 Abstract    Microsomes isolated from excised shoots of 3-day-old. dark grown, grain sorghum [Sor­ ghum bicolor (L.) Moench, Funk G522DR and DK 41Y] and corn seedlings [Zea mays (L.), Pioneer 3245] metabolized the sulfonylurea herbicide prosulfuron (CGA-152005). Corn microsomes predominantly formed a single major metabolite that resulted from hydroxyla-tion of the phenyl ring at the C5 position. However, sorghum microsomes formed two major metabolites in an approximate 1:1 ratio. One was the 5-hydroxyphenyl metabolite, whereas the second metabolite resulted from ö-demethylation at C4 of the triazine ring. Metabolite identity was established by mass spectrometry and co-chromatography with authentic stan­ dards. Metabolism in both corn and sorghum was greatly enhanced by pretreatment of the seed with naphthalic anhydride and by subirrigation with 2.5% ethanol 24 h prior to harvest. Metabolism required a reduced pyridine nucleotide and was affected by several cytochrome P450 monooxygenase inhibitors (carbon monoxide, tetcyclacis, piperonyl butoxide, 1 amino-benzotriazole, and SKF-525A). The inhibitors differentially affected metabolism of prosul­ furon. Microsomal oxidations from both untreated and inducer-treated tissue responded simi­ larly to the inhibitors. In exploratory studies, microsomes isolated from shoots of wheat [Triticum aestivum L., Pioneer 2548], barley [Hordeum vulgare L., Boone], oats [Avena sativa L., Southern States 76-30-P242] and rice [Oryza sativa L" Gulfmont], and room ripened avocado [Persea americana, Mill., Hass] mesocarp tissue also primarily formed the 5-hydroxy-phenyl metabolite. Titration of seven different avocado microsomal preparations with prosul­ furon provided typical type I difference spectra from which an average binding constant (/Cs) of 187 ± 35 [.im was obtained. Abbreviations: 1-ABT, 1-aminobenzotriazole; alachlor, 2-chloro-.'V-(2.6diethylphenyl)-/V-(methoxymethyl)acet-amide; ALS, acetolactate synthase; CG A 24704, 2-chloro-N-(2,6-dimethylphenyl)-/V-(2-methoxy-l-methylethyl)acet-amide; CGA-150829. 2-amino-4-methoxy-6-methyl-l,3,5-triazine; CGA-152005, prosulfuron, N-[[(4-methoxy-6-methyl-l,3,5-triazin-2-yl) amino]carbonyl]-2-(3,3,3-trifluoropropyl)benzenesulfonamide; CGA -l59902, 2-(3,3,3-tri-fluoropropyl)benzenesulfonamide; CGA-300406, 0-desmethyl prosulfuron, N[[(4-hydroxy-6-methyl-l,3,5-triazin-2-yl)amino]carbonyl]-2-(3,3,3-trifluoropropyl)benzenesulfonamide; CGA-300408, 5-hydroxy prosulfuron, N-[[(4me-thoxy-6-methyl-l,3,5-triazin-2-yl)amino]carbonyl]-2-(3,3,3-trifluoropropyI)-5-hydroxybenzenesulfonamide; chlorsul-furon, l-(2-chlorophenylsulfonyl)-3-(4-methoxy-6-methyl-l,3.5-triazin-2-yl)urea; pCMA, /?-chloro-./V-methylaniline: DMA, /V,/V-dimethylaniline; DMSO. dimethyl sulfoxide; DTT, dithiothreitol; G6P. glucose-6-phosphate; HPLC, high-performance liquid chromatography; LC/ESI/MS. liquid chromatography/ electrospray ionization/mass spectrome­ try; metolachlor, 2-chloro-/V-(2-ethyl-6-methylphenyl)-/V-(2-methoxy-l-methylethyl)acetamide; NA. 1,8-naphthalic anhydride; nicosulfuron, 2-[[(4.6-dimethoxypyrimidin-2-yl)aminocarbonyl]aminosulfonyl]-./V,/V-dimethyl-3-pyridinec-arboxamide; PBO. piperonyl butoxide; primisulfuron. 2-[[[[[4.6-bis(difluoromethoxy)-2pyrimidinyl]amino]carbony-l]amino]sulfonyl]benzoic acid: PVPP. polyvinylpolypyrrolidone; SKF-525A. 2-(diethylamino)ethyl-2.2-diphenylpen-tanoate; tetcyclacis, 5-(4-chlorophenyl)-3,4.5.9,10-pentaazatetracyclo[5.4.102-6,0811] dodeca-3.9-diene; TLC. thin layer chromatography: triasulfuron, l-(2-chloroethoxyphenylsulfonyl)-3-(6-methoxy-4-methyl-l,3.5-triazin-2-yl)urea. Reprint requests to Dr. D. E. Moreland. Telefax: (001) 919-515-7959. 0939-5075/96/0900-0698 $ 06.00 © 1996 Verlag der Zeitschrift für Naturforschung. All rights reserved. D D. E. Moreland et al. ■ M etabolism of Prosulfuron by Plant Microsomes 699 
  Reference    Z. Naturforsch. 51c, 698—710 (1996); received May 14/June 17 1996 
  Published    1996 
  Keywords    Microsomes, Prosulfuron, Cytochrome P450, Mixed Function Oxidases, Herbicide Metabolism 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0698.pdf 
 Identifier    ZNC-1996-51c-0698 
 Volume    51