Abstract
Interest in pharmacological agents capable of increasing cellular NAD+ concentrations has stimulated investigations of nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). NR and NMN require large dosages for effect. Herein, we describe synthesis of dihydronicotinamide riboside (NRH) and the discovery that NRH is a potent NAD+ concentration-enhancing agent, which acts within as little as 1 h after administration to mammalian cells to increase NAD+ concentrations by 2.5-10-fold over control values. Comparisons with NR and NMN show that in every instance, NRH provides greater NAD+ increases at equivalent concentrations. NRH also provides substantial NAD+ increases in tissues when administered by intraperitoneal injection to C57BL/6J mice. NRH substantially increases NAD+/NADH ratio in cultured cells and in liver and no induction of apoptotic markers or significant increases in lactate levels in cells. Cells treated with NRH are resistant to cell death caused by NAD+-depleting genotoxins such as hydrogen peroxide and methylmethane sulfonate. Studies to identify its biochemical mechanism of action showed that it does not inhibit NAD+ consumption, suggesting that it acts as a biochemical precursor to NAD+ Cell lysates possess an ATP-dependent kinase activity that efficiently converts NRH to the compound NMNH, but independent of Nrk1 or Nrk2. These studies identify a putative new metabolic pathway to NAD+ and a potent pharmacologic agent for NAD+ concentration enhancement in cells and tissues.
Highlights
Interest in pharmacological agents capable of increasing cellular NAD؉ concentrations has stimulated investigations of nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN)
We prepared the compound from nicotinamide riboside triflate, via published synthetic methodology developed by our laboratory (17)
Additional properties of NRH are provided in the supporting information, including its UV spectrum, which is centered at 340 nm
Summary
To better investigate the properties of NRH (Scheme 1) as a potential NADϩ precursor, a method of preparation of the compound was required, preferably by direct chemical synthesis. The concentration of NRH required to achieve 260% NADϩ concentration increase as compared with control was determined to be 34 M, whereas 1 mM NR is required to achieve the same increase in this cell line (17), and NMN does not achieve doubling of NADϩ concentration at 1 mM (Fig. S3). These data provide a relative potency increase of ϳ30-fold versus NR for this cell line. A dose-response profile was determined for primary neurons, obtained as described previously (28) These cells were treated with increasing concentrations of NRH for a period of 6 h. Robust NADϩ elevation caused by treatment of NRH remained evident after 18 h in HEK293 cells (Fig. 2d), in part due to persistence of the majority NRH in medium past a time of 18 h (Fig. S2)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
