Electrochemical Characterization of Nicotinamide Riboside

AbstractTo improve quality of life, nicotinamide riboside (NR) has become a go‐to supplement to serve as a precursor to nicotinamide adenine dinucleotide (NAD+/NADH). NAD+ is a cofactor used in various extra‐ and intra‐cellular metabolic pathways by enzymes that maintain physiological functions like vision, hearing, and cognitive behavior. Unfortunately, innate NAD+ levels decline over time giving rise to a need for NAD+ boosters like NR to fight age‐related diseases. To better understand redox pathways of NR in biological systems, we chose to study the electrochemistry of NR. Here, we electrochemically characterize NR in aqueous solutions using voltammetry, amperometry, bulk electrolysis, and mass spectrometry. We found the reduction of NR (Ep,c=−1.1 V vs. Ag/AgCl) is a diffusion‐controlled reaction and calculated a diffusion coefficient of 4.6 0.1×10−6 cm2 ⋅ s−1. Square wave voltammetry indicated NR is reduced by one electron, and cyclic voltammetry suggested a major kinetic product, oxidizable at Ep,a=+0.15 V vs. Ag/AgCl. Bulk electrolysis confirmed the species at +0.15 V vs. Ag/AgCl was a kinetic product, and liquid chromatography‐mass spectrometry of the bulk electrolysis products revealed the thermodynamic product was a dimer (NR2). Finally, we studied the reduction of NR in whole cell lysate, which is shown to differ markedly from simple buffer solutions.