1806-98-0

A library of steroid glucuronides was prepared using the glucuronylsynthase derived from Escherichia coli β-glucuronidase, followed by purification using solid-phase extraction. A representative range of steroid substrates were screened for synthesis on t

An automated synthesis system using a solid-phase extraction (SPE) system and column packed with octadecylsilica (ODS), which was coated with phospholipid and loaded with dog liver microsomes, was developed for synthesis of glucuronides. Preparation of the microsome-immobilized SPE column, glucuronidation of drugs to synthesize the glucuronides and elution of the products were performed by an automated synthesis system. The phospholipid-coated SPE column and then the microsome-immobilized SPE column were readily prepared by allowing a solution containing L-α- dipalmitoylphosphatidylcholine to flow through the SPE column, and then by recycling a buffer solution containing dog liver microsomes through the resulting phospholipid-coated SPE column. The microsome-immobilized SPE column exhibiting the uridine diphosphate (UDP)-glucuronosyltransferase activity catalyzed the glucuronidation of mefenamic acid and estradiol to the corresponding glucuronides in the presence of UDP-glucuronic acid, and three glucuronides of mefenamic acid and estradiol were synthesized using the automated synthesis system, by simply recycling a buffer solution containing UDP-glucuronic acid through the microsome-immobilized SPE column loaded with the substrate. We used β-cyclodextrin as a solubilizing agent for the synthesis of the glucuronides of estradiol that is practically insoluble in aqueous solutions. The productivity of these glucuronides using the microsome-immobilized SPE column was higher than that using the free microsomes (batch method). Furthermore, we developed a fully automated synthesis-isolation system by coupling the automated synthesis system to an automated preparative HPLC system. The automated synthesis system as well as the fully automated synthesis-isolation system should be very useful for synthesizing glucuronides for drug development.

The chimpanzee has recently been characterized as a surrogate for oxidative drug metabolism in humans and as a pharmacokinetic model for the selection of drug candidates. In the current study, the glucuronidation of acetaminophen, morphine and oestradiol was evaluated in the chimpanzee to extend the characterization of this important animal model. Following oral administration of acetaminophen (600 mg) to chimpanzees (n = 2), pharmacokinetics were comparable with previously reported human values, namely mean oral clearance 0.91 vs. 0.62 ± 0.05 l h-1 kg-1, apparent volume of distribution 2.29 vs. 1.65 ± 0.25 l kg-1, and half-life 1.86 vs. 1.89 ± 0.27 h, for chimpanzee vs. human, respectively. Urinary excretions (percentage of dose) of acetaminophen, acetaminophen glucuronide and acetaminophen sulfate were also similar between chimpanzees and humans, namely 2.3 vs. 5.0, 63.1 vs. 54.7, and 25.0 vs. 32.3%, respectively. Acetaminophen, oestradiol and morphine glucuronide formation kinetics were investigated using chimpanzee (n = 2) and pooled human liver microsomes (n = 10). V maxapp and Kmapp (or S 50app) for acetaminophen glucuronide, morphine 3- and 6-glucuronide, and oestradiol 3- and 17-glucuronide formation were comparable in both species. Eadie-Hofstee plots of oestradiol 3-glucuronide formation in chimpanzee microsomes were characteristic of autoactivation kinetics. Western immunoblot analysis of chimpanzee liver microsomes revealed a single immunoreactive band when probed with anti-human UGT1A1, anti-human UGT1A6, and anti-human UGT2B7. Taken collectively, these data demonstrate similar glucuronidation characteristics in chimpanzees and humans.

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