Generation of statin drug metabolites through electrochemical and enzymatic oxidations
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The generation of key drug metabolites for the purpose of their complete structural characterization, toxicity testing, as well as to serve as standards for quantitative studies, is a critical step in the pharmaceutical discovery and development cycle. Here, we utilized electrochemistry/mass spectrometry for the detection and subsequent generation of six phase I metabolites of simvastatin and lovastatin. Both simvastatin and lovastatin are widely used for the treatment of hypercholesterolemia. There are known drug–drug interaction issues of statin therapy, and it has been suggested that the oxidative metabolites may contribute to the cholesterol-lowering effect of both statins. Of the known phase I metabolites of simvastatin and lovastatin, none are commercially available, and chemical means for the synthesis of a very few of them have been previously reported. Here, we report that electrochemical oxidation of less than 1 mg each of simvastatin and lovastatin led to the generation of three oxidative metabolites of each parent to allow complete nuclear magnetic resonance characterization of all six metabolites. The yields obtained by the electrochemical approach were also compared with incubation of parent drug with commercially available bacterial mutant CYP102A1 enzymes, and it was found that the electrochemical approach gave higher yields than the enzymatic oxidations for the generation of most of the observed oxidative metabolites in this study.
KeywordsElectrochemistry Electrochemistry/mass spectrometry (EC/MS) Metabolite generation Simvastatin Lovastatin CYP102A1
The authors would like to acknowledge Chuck Li (Amgen Inc.) for developing the MATLAB script for recording mass-voltammograms, Chris Fotsch (Amgen Inc.) for the methodology used in this work to conduct the enzymatic incubations, Martin Eysberg, Jim Powers, and Joann Purkerson (Antec, USA) for training on the EC/MS platform as well as helpful discussions, and Nanosyn (Santa Clara, CA, USA) for performing the mass-directed metabolite purification of the dihydrodiol metabolites. We also acknowledge the Amgen Summer Internship program which made this manuscript possible.
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