Fred S. Tanaka

Metribuzin metabolism in tomato: Isolation and identification of N-glucoside conjugates☆☆☆

Abstract Metribuzin [4-amino-6- tert -butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one] metabolism was studied in tomato ( Lycopersicon esculentum Mill. “Sheyenne”). Pulse-treatment studies with seedlings and excised leaves showed that [5- 14 C]metribuzin was rapidly absorbed, translocated (acropetal), and metabolized to more polar products. Foliar tissues of 19-day-old seedlings metabolized 96% of the root-absorbed [ 14 C]metribuzin in 120 hr. Excised mature leaves metabolized 85–90% of the petiole-absorbed [ 14 C]metrubuzin in 48 hr. Polar metabolites were isolated by solvent partitioning, and purified by adsorption, thin-layer, and high-performance liquid chromatography. A minor intermediate metabolite (I) was identified as the polar β- d -( N -glucoside) conjugate of metribuzin. The biosynthesis of (I) was demonstrated with a partially purified UDP-glucose: metribuzin N -glucosyltransferase from tomato leaves. A possible correlation between foliar UDP-glucose: metribuzin N -glucosyltransferase activity levels and differences in the tolerance of selected tomato seedling cultivars to metribuzin was suggested. The major polar metabolite (II) was identified as the malonyl β- d -( N -glucoside) conjugate of metribuzin.

Photolysis of 3‐(3,4‐dichlorophenyl)‐1, 1 ‐Dimethylurea (Diuron) in dilute aqueous solution

Diuron samples at 40mg/L concentration were photolyzed with ultraviolet lamps and with natural sunlight to determine if data from ultraviolet lamp photolysis could be used to predict results from sunlight photolysis. Seven photoproducts were identified from the photolysis experiments. The identified photoproducts and the photoproduct yields were essentially the same for the two light sources.

Chlorimuron ethyl metabolism in corn

Abstract [14C]Chlorimuron ethyl was readily absorbed by the roots of young intact corn seedlings and through the cut ends of excised leaves, but it was not readily absorbed by intact leaves. Under the conditions employed, [14C]chlorimuron ethyl was metabolized at a moderate rate in both intact roots and excised leaves (ca. 2.4 nmol/g fresh wt tissue/hr). Based upon high-performance liquid chromatography (HPLC) analysis, [14C]chlorimuron ethyl appeared to be metabolized by similar routes in both the roots and leaves. [14C]Chlorimuron ethyl and 10 radioactive metabolites were detected in the roots of corn 7 hr following herbicide treatment. [14C]Chlorimuron ethyl and seven metabolites, listed in approximate order of their abundance, were isolated and characterized: chlorimuron ethyl (N-[4-chloro-6-methoxypyrimidine-2-yl]-N′-[2-ethoxycarbonylbenzenesul-fonyl]urea; (I) N-(4-chloro-5-hydroxy-6-methoxypyrimidine-2-yl)-N′-(2-ethoxycarbonylbenzene-sulfonyl)urea; (II) 2-ethoxycarbonylbenzene sulfonamide, (IV) N-(4-[S-glutathionyl]-6-methoxypyrimidine-2-yl)-N′(2-ethoxycarbonylbenzenesulfonyl)urea, (VI) N-(4-[S-glutathionyl]-5-hydroxy-6-methoxypyrimidine-2-yl)-N′-(2-ethoxycarbonylbenzenesulfonyl)urea, (III) N-(4-chloro-5-[O-β- d -glucosyl]-6-methoxypyrimidine-2-yl)-N′-(2-ethoxycarbonylbenzenesulfonyl)urea, (VII) N-(4-chloro-6-methoxypyrimidine-2-yl)-N′-(2-ethoxy-?-[O-β- d -glucosyl]benzenesulfonyl)urea, and (V) N-(4-[S-cysteinyl]-6-methoxypyrimidine-2-yl)-N′-(2-ethoxycarbonylbenzenesulfonyl)urea. Chlorimuron ethyl and these metabolites were purified by HPLC and were characterized by fast atom bombardment mass spectrometry (FAB MS). In addition to FAB MS, the following methods were used in the characterization of some metabolites: synthesis, hydrolysis with β-glucosidase, analysis of hydrolysis products, electron impact mass spectrometry, and proton nuclear magnetic resonance (400 MH).

Photolysis of 3‐(3,4‐dichlorophenyl)‐1‐methoxy‐1 ‐Methylurea (Linuron) in dilute aqueous solution

Linuron samples at 75mg/L concentration were photolyzed with ultraviolet lamps or with natural sunlight. Ten photoproducts were identified and yields were determined for the more significant photoproducts resulting from either sunlight or ultraviolet lamp photolysis.

A Regiospecific Photoreaction for Synthesis of 3-Phenylpyridines

Abstract The regiospecific photocoupling of 3-(4-chloro-phenyl)-1,1-rdimethylurea with pyridine to afford 3-(4-dimethyl-ureidophenyl)pyridine was used to develop a synthetic scheme for the preparation of 3-phenylpyridine.

Test for photosynthetic inhibition by bis(N′,N′-dimethylureido)biphenyl photoproducts of monuron

Abstract Five substituted biphenyl photoproducts were identified from the photolysis of 3-(4-chlorophenyl)-1, 1-dimethylurea (monuron) under varying solution conditions. These photoproducts contained functional groups that conferred phytotoxic properties to phenylurea herbicides. Therefore, a study was conducted to determine if these biphenyl photoproducts at 1, 10 and 100 μM concentrations could exhibit phytotoxic effects using the Hill reaction as the biological assay. The results show that virtually no inhibitory effects were observed from the bis-(N′,N′-dimethylureido)biphyenyl photoproducts at any of the above concentrations.