Tebuconazole-d₉is intended for use as an internal standard for the quantification of tebuconazole by GC- or LC-MS. Tebuconazole is a triazole fungicide that is active against both seed and foliar fungi.¹It inhibits 14α-demethylase isolated fromU. maydisandS. bicolorwith IC₅₀values of 0.05 and 0.16 nM, respectively.²It inhibits the androgenic effect of the androgen receptor agonist DHT (IC₂₀= 2.89 µM) and is cytotoxic (EC₂₀= 38.9 µM) in an MDA-kb2 assay.³Tebuconazole (50 and 100 mg/kg per day) administered during gestation reduces testosterone levels and increases testicular levels of progesterone and 17α-hydroxyprogesterone in male rat fetuses.⁴It has a feminizing effect on male pups and a virilizing effect on female pups. When administered to rats gestationally through postnatal day 42, tebuconazole (20 and 60 mg/kg per day) leads to cell death of pyramidal cells in the CA3-4 region of the hippocampus and layer V of the cortex concomitant with impairment in learning the platform location in the Morris water maze.⁵

1.Reinecke, P., Kaspers, H., Scheinpflug, H., et al.BAY HWG 1608, a new fungicide for foliar spray and seed-treatment use against a wide spectrum of fungal pathogensBr. Crop Prot. Conf.--Pests Dis., Proc. 141-46(1986) 2.Zarn, J.A., BrÜschweiler, B.J., and Schlatter, J.R.Azole fungicides affect mammalian steroidogenesis by inhibiting sterol 14 α-demethylase and aromataseEnviron. Health Perspect.111(3)255-261(2003) 3.Orton, F., Rosivatz, E., Scholze, M., et al.Widely used pesticides with previously unknown endocrine activity revealed as in vitro antiandrogensEnviron. Health Perspect.119(6)794-800(2011) 4.Taxvig, C., Hass, U., Axelstad, M., et al.Endocrine-disrupting activities in vivo of the fungicides tebuconazole and epoxiconazoleToxicol. Sci.100(2)464-473(2007) 5.Moser, V.C., Barone, S., Jr., Smialowicz, R.J., et al.The effects of perinatal tebuconazole exposure on adult neurological, immunological, and reproductive function in ratsToxicol. Sci.62(2)339-352(2001)