title: Enzyme-assisted synthesis and structural characterization of nitrocatechol glucuronides.
abstract: Enzyme-assisted synthesis and characterization are described for 3-O-beta-D-glucuronides 1b-4b of the aglycons E- and Z-2-cyano-N, N-diethyl-3-(3,4-dihydroxy-5-nitrophenyl)propenamide (entacapone), 1a and 2a, respectively, 3-(3,4-dihydroxy-5-nitrobenzylidene)-2, 4-pentanedione (nitecapone) 3a and 4'-methyl-3, 4-dihydroxy-5-nitrobenzophenone (tolcapone) 4a, and 1-o- and 2-o-glucuronides 5b and 6b of the aglycon 1, 2-dihydroxy-4-nitrobenzene 5a. Liver microsomes from rats pretreated with Aroclor 1254 were used as catalyst in the synthesis. Glucuronidation was regio- and stereoselective in the case of 1a-4a; only one product was observed by HPLC, HPTLC, and NMR. The glucuronidation of 1,2-dihydroxy-4-nitrobenzene 5a resulted in equal amounts of 1-O-beta-D- and 2-O-beta-D-glucuronides. Purification of the crude products by C18 solid-phase extraction and/or flash chromatography gave compounds 1b-6b in 38-98% yields (50-84 mg). The structures of the glucuronides were characterized on the basis of UV and IR spectra and confirmed with FAB-MS and NMR spectroscopy.
authors.affiliation: Department of Pharmacy, Division of Pharmaceutical Chemistry, POB 56, FIN-00014, University of Helsinki, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Luukkanen
authors.forename: I
authors.initials: I
authors.lastname: Kilpeläinen
authors.forename: H
authors.initials: H
authors.lastname: Kangas
authors.forename: P
authors.initials: P
authors.lastname: Ottoila
authors.forename: E
authors.initials: E
authors.lastname: Elovaara
authors.forename: J
authors.initials: J
authors.lastname: Taskinen
mesh_terms: D000818:Animals; D001577:Benzophenones / Q000138:chemical synthesis* / Q000737:chemistry; D065098:Catechol O-Methyltransferase Inhibitors; D002396:Catechols / Q000138:chemical synthesis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry; D005965:Glucuronates / Q000138:chemical synthesis* / Q000737:chemistry; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D009570:Nitriles; D009596:Nitrophenols; D010422:Pentanones / Q000138:chemical synthesis* / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D000077867:Tolcapone
chemical_list: D001577:Benzophenones; D065098:Catechol O-Methyltransferase Inhibitors; D002396:Catechols; D004791:Enzyme Inhibitors; D005965:Glucuronates; D009570:Nitriles; D009596:Nitrophenols; D010422:Pentanones; C071192:entacapone; C057364:nitecapone; D000077867:Tolcapone