Metabolism of a novel hypnotic,N3-phenacyluridine,and hypnotic and sedative activities of its enantiomer metabolites in mouse |
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| Authors: | T. Kimura M. Miki K. Watanabe S. Kondo I. K. Ho I. Yamamoto |
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| Affiliation: | 1. Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Hokuriku University, 3-Ho, Kanagawa-machi, Kanazawa 920-1181, Japan;2. Nissui Pharmaceutical Co., Ltd, Yuuki Ibaraki 307-0036, Japan;3. Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA |
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| Abstract: | 1. The metabolism of N3-phenacyluridine (3-phenacyl-1- beta-D-ribofuranosyluracil), a potent hypnotic nucleoside derivative, was studied in mouse. 2. Of the radioactivity, 65% was excreted in urine within 48 h after intraperitoneal (i.p.) administration of [3H] N3-phenacyluridine. The urinary metabolites N3-phenacyluracil and N3-alpha-hydroxy-beta-phenethyluridine were extracted, isolated and analyzed by mass spectrometry. 3. Racemates of N3-alpha-hydroxy-beta-phenethyluridine were synthesized and both isomers were separated as N3-(S)-(+)-alpha-hydroxy-beta-phenethyluridine and N3-(R)-(-)-alpha hydroxy-beta-phenethyluridine by hplc (CHIRALCEL-OJ column) with retentions of 13.8 and 17.9 min respectively. The reduction process took place with high stereo-selectivity, which gave an alcohol product in the urine with the same retention (17.9 min) as one of the synthetic isomers separated by hplc. 4. One of urinary metabolites was identified as N3-(S)-(+)-alpha-hydroxy-beta-phenethyluridine. N3-phenacyluridine was predominantly converted to an alcoholic metabolite of (S)-(+)-configuration. 5. N3-phenacyluracil and uridine were also identified as minor metabolites. 6. The pharmacological effects of the metabolites and related compounds were also evaluated in mouse. N3-(S)-(+)-alpha-hydroxy-beta-phenethyluridine, but not N 3-(R)-(-)-alpha hydroxy-beta-phenethyluridine, possessed hypnotic activity and potentiated pentobarbitalinduced sleeping time with a similar potency to the parent compound, N3-phenacyluridine. N3-alpha-hydroxy-beta-phenethyluridine (racemate) had almost two thirds of the hypnotic activity of N3-(S)-(+)- alpha-hydroxy-beta-phenethyluridine. No other metabolites exhibited hypnotic activities. 7. The present study indicates that N3-(S)-(+)-alpha-hydroxy-beta-phenethyluridine, a major metabolite of N3-phenacyluridine, is an active metabolite and contributes a significant CNS depressant effect. |
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