title: New metabolites of thiabendazole and the metabolism of thiabendazole by mouse embryo in vivo and in vitro.
abstract: Thiabendazole [2-(4'-thiazolyl)benzimidazole; TBZ], a teratogen in ICR mice, is known to be mainly metabolized to 5-hydroxy-TBZ (5-OH-TBZ) and its conjugates in domestic and laboratory animals. Besides the known metabolites of TBZ, 4-hydroxy-TBZ and 2-acetylbenzimidazole (ABI) were identified as new metabolites of TBZ in the urine of F344 rats and ICR mice. 5-OH-TBZ and ABI, as well as TBZ, were found in the embryos of ICR mice given TBZ orally on day 10 of gestation. In the whole-embryo culture system, 5-OH-TBZ and ABI in the medium, and TBZ, 5-OH-TBZ and ABI in the embryo were detected after 24 hr of culture in 25 or 50 micrograms TBZ ml. However, the amount of metabolites in the embryo in vitro was very small compared with that detected in vivo, whereas the amount of TBZ was comparable. Furthermore, the mouse embryo homogenate, at organogenesis, metabolized TBZ to 5-OH-TBZ or ABI. The specific activity required by this homogenate to form 5-OH-TBZ or ABI was less than 1/1000 of that of the liver microsomal fraction. The results suggested that mouse embryos at organogenesis could metabolize TBZ, although most of the metabolites in the embryo in vivo came from the dam.
authors.affiliation: Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujitani
authors.forename: M
authors.initials: M
authors.lastname: Yoneyama
authors.forename: A
authors.initials: A
authors.lastname: Ogata
authors.forename: T
authors.initials: T
authors.lastname: Ueta
authors.forename: K
authors.initials: K
authors.lastname: Mori
authors.forename: H
authors.initials: H
authors.lastname: Ichikawa
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004622:Embryo, Mammalian / Q000378:metabolism*; D005260:Female; D005865:Gestational Age; D066298:In Vitro Techniques; D008297:Male; D013058:Mass Spectrometry; D008431:Maternal-Fetal Exchange; D051379:Mice; D008813:Mice, Inbred ICR; D008862:Microsomes, Liver / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D013723:Teratogens / Q000378:metabolism*; D013827:Thiabendazole / Q000378:metabolism* / Q000633:toxicity; D014018:Tissue Distribution; D015017:Yolk Sac / Q000378:metabolism
chemical_list: D013723:Teratogens; D013827:Thiabendazole