title: Metabolism of a new herbicide, [(14)c]pyribenzoxim, in rice.
abstract: The in vivo metabolism of a new herbicide pyribenzoxim (benzophenone Ο-[2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoyl]oxime) in rice was carried out using container trials. Two radiolabeled forms of [carbonyl-(14)C]pyribenzoxim (P1) and [ring-(14)C(U)]pyribenzoxim (P2) were treated separately as formulations for foliar treatment by single applications of 50 g of active ingredient (ai)/ha at the 4-6 leaves stage. At 0, 7, 30, and 60 days after treatment (DAT), samples of panicle, foliage/rest of plant, and roots were taken for analysis. Upon harvest (120 DAT), rice plants were separated into grain, husk, straw, and root parts. Total radioactive residues (TRRs) at each sampling date were determined to show that the final radioactive residues at harvest were low in grain, husk, straw, and roots, accounting for <17 ppb. The concentration of final residues in the rice plant decreased rapidly, and less than 0.1% of initial TRRs remained at harvest. At 7 DAT, metabolite 1 [M1, 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid] and two unknown compounds (other-1 and other-2) were detected in foliage extract, accounting for 3.5% TRRs (21.0 ppb), 3.1% TRRs (19.0 ppb), and 9.0% TRRs (54.3 ppb), respectively, while 26.1% of M1 was observed in solvent wash. Any other metabolites were not detected in the plant, including expected metabolite M3 (benzophenone oxime). On the basis of the results obtained, a metabolic pathway of pyribenzoxim in a rice plant was proposed.
authors.affiliation: Environmental Toxicology Division, Toxicological Research Center, Hoseo University , 165 Sechul, Baebang, Asan, Chungnam 336-795, Korea.
authors.forename: Hee-Ra
authors.initials: HR
authors.lastname: Chang
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Keum
authors.forename: Suk-Jin
authors.initials: SJ
authors.lastname: Koo
authors.forename: Joon-Kwan
authors.initials: JK
authors.lastname: Moon
authors.forename: Kyun
authors.initials: K
authors.lastname: Kim
authors.forename: Jeong-Han
authors.initials: JH
authors.lastname: Kim
mesh_terms: D001577:Benzophenones / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D002250:Carbon Radioisotopes; D006540:Herbicides / Q000378:metabolism*; D012275:Oryza / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry
chemical_list: D001577:Benzophenones; D002250:Carbon Radioisotopes; D006540:Herbicides; C454324:benzophenone O-(2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoyl)oxime