title: LC-1H NMR used for determination of the elution order of S-naproxen glucuronide isomers in two isocratic reversed-phase LC-systems.
abstract: The reactive metabolite S-naproxen-beta-1-O-acyl glucuronide was purified from human urine using solid phase extraction (SPE) and preparative HPLC. The structure was confirmed by 600 MHz 1H NMR. Directly coupled 600 MHz HPLC-1H NMR was used to assign the peaks in chromatograms obtained when analysing a sample containing S-naproxen aglycone and the 1-, 2-, 3-, and 4-isomers of S-naproxen-beta-1-O-acyl glucuronide in two simple isocratic reversed phase HPLC-systems. Using mobile phase 1 (50 mM formate buffer pH 5.75/acetonitrile 75:25 v/v) the elution order was: 4-O-acyl isomers, beta-1-O-acyl glucuronide, 3-O-acyl isomers, 2-O-acyl isomers, and S-naproxen aglycone. Using mobile phase II (25 mM potassium phosphate pH 7.40/acetonitrile 80:20 v/v) the elution order was: alpha/beta-4-O-acyl isomers, S-naproxen aglycone, beta-1-O-acyl glucuronide, 3-O-acyl isomers, and alpha/beta-2-O-acyl isomers. In both systems the elution order for the 2-, 3- and 4-O-acyl isomers corresponded with previously published results for 2-, 3-, and 4-fluorobenzoic acid glucuronide isomers determined by reversed phase HPLC-1H NMR (U.G. Sidelmann, S.H. Hansen, C. Gavaghan, A.W. Nicholls, H.A.J. Carless, J.C. Lindon, I.D. Wilson, J.K. Nicholson, J. Chromatogr. B Biomed. Appl. 685 (1996) 113-122]. The alpha-1-O-acyl isomer was found to be present at approximately 3% of the initial S-naproxen-beta-1-O-acyl glucuronide concentration in the glucuronide isomer mixture after 6 h of incubation at pH 7.40 and 37 degrees C. In both HPLC systems it eluted just before the beta-1-O-acyl glucuronide well separated from other isomers. Investigators should consider the possible formation of a alpha-1-O-acyl isomer when studying glucuronide reactivity and degradation.
authors.affiliation: Department of Analytical and Pharmaceutical Chemistry, Royal Danish School of Pharmacy, Copenhagen. rasmus.mortensen@leo-pharma.com
authors.forename: R W
authors.initials: RW
authors.lastname: Mortensen
authors.forename: O
authors.initials: O
authors.lastname: Corcoran
authors.forename: C
authors.initials: C
authors.lastname: Cornett
authors.forename: U G
authors.initials: UG
authors.lastname: Sidelmann
authors.forename: J
authors.initials: J
authors.lastname: Troke
authors.forename: J C
authors.initials: JC
authors.lastname: Lindon
authors.forename: J K
authors.initials: JK
authors.lastname: Nicholson
authors.forename: S H
authors.initials: SH
authors.lastname: Hansen
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D020719:Glucuronides / Q000737:chemistry / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009288:Naproxen / Q000737:chemistry / Q000302:isolation & purification*; D011522:Protons; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
chemical_list: D020719:Glucuronides; D011522:Protons; D009288:Naproxen