Nicotinamide Riboside and Nicotinic Acid Riboside Metabolism in Fungi and Mammals: Preclinical Findings

Synopsis

NAD+ is an important coenzyme that helps many cellular reactions and supports enzymes like sirtuins, which regulate aging and stress responses. In yeast, adding nicotinamide riboside (NR) boosts NAD+ levels, activates Sir2, and extends lifespan. NR can raise NAD+ through two pathways: one using the NRK enzyme and another that breaks NR into nicotinamide, which cells can recycle. Certain enzymes, like uridine hydrolase and purine nucleoside phosphorylase, are needed for NR use without NRK. This study shows that in mammals, purine nucleoside phosphorylase helps metabolize NR, while methylthioadenosine phosphorylase does not. It also finds that uridine hydrolase works better on NR than on uridine and that both uridine hydrolase and purine nucleoside phosphorylase can process nicotinic acid riboside. In yeast, using nicotinic acid riboside mainly depends on uridine hydrolase and NRK, and adding an ester to it improves how well cells can use it.

Journal

Journal of Biological Chemistry