RT Journal Article SR Electronic T1 Isolation and Identification of Diglucuronides of Some Endogenous Steroids in Dogs JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 368 OP 374 DO 10.1124/dmd.107.019059 VO 36 IS 2 A1 Takahiro Murai A1 Naotoshi Yamamura A1 Takashi Nitanai A1 Naozumi Samata A1 Makoto Takei A1 Haruo Iwabuchi A1 Kohji Tanaka A1 Kei Mikamoto A1 Toshihiko Ikeda YR 2008 UL http://dmd.aspetjournals.org/content/36/2/368.abstract AB Diglucuronidation is a novel glucuronidation reaction where the second glucuronosyl moiety is attached at the C2′ position of the first glucuronosyl moiety. To examine whether diglucuronidation takes place in endogenous substrates in vivo, control urine and bile samples were collected from male Crl:CD(SD) IGS rats, beagle dogs, and cynomolgus monkeys and analyzed by liquid chromatography-mass spectrometry (LC-MS) after solid phase extraction. Several diglucuronides of C19 steroids, including M1 (C31H46O14) and M2 (C31H44O14), were detected in the urine and bile of the dogs but not in the excreta of the rats and monkeys. A milligram quantity of M1 was successfully isolated from the pooled dog urine and analyzed by nuclear magnetic resonance (NMR) spectroscopy. M1 was unambiguously identified as epiandrosterone 3-O-diglucuronide by comparing the LC-MS and two-dimensional NMR data of M1 with those of the biosynthesized epiandrosterone 3-O-diglucuronide. M2 was identified as dehydroepiandrosterone 3-O-diglucuronide. According to these findings, the diglucuronidation reaction was proven to be occurring on steroid hormones in vivo in dogs. The American Society for Pharmacology and Experimental Therapeutics