title: Analysis of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors using liquid chromatography-electrospray mass spectrometry.
abstract: Employing high-performance liquid chromatography-electrospray mass spectrometry, we describe a new assay for monitoring 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity. Incubations were carried out with HMG-CoA reductase (rat liver), HMG-CoA and NADPH, and terminated by the addition of HCl. The reaction product, mevalonolactone, and internal standard, were extracted with ethyl acetate, dissolved in methanol, and analyzed by LC-MS. Using an isocratic mobile phase of 10% acetonitrile and 0.1% formic acid (flow-rate, 0.2 ml/min), the protonated molecules of mevalonolactone at m/z 131 and internal standard, beta,beta-dimethyl-gamma-(hydroxymethyl)-gamma-butyrolactone, at m/z 145, were detected using selected ion monitoring. The limit of detection was approximately 6.5 pg, and the limit of quantitation was approximately 16.3 pg. Extraction recovery was >90%. The relative standard deviations for intra- and inter-day assays were approximately 4.1+/-2.7 and 9.4+/-3.4%, respectively. Mevalonolactone was examined over a period of 3 days and found to be stable. Using this assay, lovastatin and mevastatin inhibited HMG-CoA reductase activity with IC50 values 0.24+/-0.02 and 2.16+/-0.31 microM, respectively. These methods offer some advantages over those reported previously which employ radiolabeled substrate and products, and should be useful in searching for compounds that could lower serum cholesterol or alter cell growth and differentiation.
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 60612, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Park
authors.forename: D
authors.initials: D
authors.lastname: Lee
authors.forename: Y G
authors.initials: YG
authors.lastname: Shin
authors.forename: D D
authors.initials: DD
authors.lastname: Lantvit
authors.forename: R B
authors.initials: RB
authors.lastname: van Breemen
authors.forename: A D
authors.initials: AD
authors.lastname: Kinghorn
authors.forename: J M
authors.initials: JM
authors.lastname: Pezzuto
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D005260:Female; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D008798:Mevalonic Acid / Q000031:analogs & derivatives* / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D012015:Reference Standards
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; C015367:mevalonolactone; D008798:Mevalonic Acid