Combination of Electrochemistry and Nuclear Magnetic Resonance Spectroscopy for Metabolism Studies

Abstract

During the development of new materials demonstrating biological activity, prediction and identification of reactive intermediates generated in the course of drug metabolism in the human liver is of great importance. We present a rapid and purely instrumental method for the structure elucidation of possible phase I metabolites. With electrochemical (EC) conversion adopting the oxidative function of liver-inherent enzymes and nuclear magnetic resonance (NMR) spectroscopy enabling structure elucidation, comprehensive knowledge on potential metabolites can be gained. Paracetamol (APAP) has been known to induce hepatotoxicity when exceeding therapeutic doses and was therefore selected as the test compound. The reactive metabolite N-acetyl-p-benzoquinone imine has long been proven to be responsible for the toxic side effects of APAP and can easily be generated by EC. EC coupled online to NMR is a straightforward technique for structure elucidation of reactive drug intermediates at an early stage in drug discovery.

Review of advances in coupling electrochemistry and liquid state NMR

“…In 2012, Simon et al [19] described an on line association between a commercial cell and a LC-NMR flow cell for metabolism studies. Authors brilliantly illustrate the powerfulness of the method through the acetaminophen (APAP) oxidation into NAPQI (Fig.…”

Solution-phase electrochemistry-nuclear magnetic resonance of small organic molecules

“…Interestingly though, a fourfold signal broadening accompanied by a four-fold reduction in [13]. B) Hyphenated EC-NMR incorporating a solid-phase extraction (SPE) step, which therefore has to be operated in stopped-flow mode.…”

“…However, EC often generates quite reactive products and intermediates (e.g., quinones and quinone imines), which may not survive collection from the EC cell and transfer to the NMR, e.g., because they react rapidly with the solvent to form secondary products. Often, these reactive products and intermediates are crucial to the investigation of electrochemical reactions {e.g., with regard to mechanistic studies [12] or in the simulation of oxidative metabolism [13]}. Therefore, the integration of EC and NMR (EC-NMR; for definition see below), which controls the delay between the generation and the measurement of EC-generated species and consequentially allows assessment of reactive entities, is quite attractive for many types of studies.…”

Electrochemical and Hyphenated Electrochemical Detectors in Liquid Chromatography and Flow Injection Systems for Drug Compound Analysis

“…The coupling of an electrochemical cell with a nuclear magnetic resonance (NMR)-flow cell has also been recently reviewed [62] and can be regarded as an additional useful approach for the identification of electrochemically generated products as illustrated for paracetamol [63]. Tables 7.2 and 7.3 show the LC-EC and FIA-EC with their hyphenated EC-MS detection systems used in the methods, respectively.…”