<unk>  ("NMN" and "β-NMN") is a nucleotide derived from ribose and<unk> . Like<unk>  riboside,<unk>  is a derivative of niacin, and humans have enzymes that can use<unk>  to generate<unk>  adenine dinucleotide (NADH). In mice,<unk>  has been proposed to enter cells via the small intestines within 10 minutes converting to NAD+ through the Slc12a8 transporter. However this observation has been challenged, and remains unsettled. Because NADH is a cofactor for processes inside mitochondria, for sirtuins, and for PARP,<unk>  has been studied in animal models as a potential neuroprotective and anti-aging agent. Dietary supplement companies have aggressively marketed<unk>  products claiming those benefits. Single-dose administration of up to 500 mg was shown safe in men in a study at Keio University School of Medicine, Shinjuku, Tokyo, Japan. A 2021 clinical trial found that<unk>  improved muscular insulin sensitivity in prediabetic women.<unk>  riboside (NR) kinase enzymes are essential for exogenously administered utilization of NR and<unk> . Some research suggests when administered exogenously,<unk>  must be converted to NR in order to enter a cell and be re-phosphorylated back to<unk> . Molecular structure comparison of<unk>  <unk>  and<unk>  riboside (NR) The molecular structures of<unk>  and NR are roughly the same, except<unk>  has an added phosphate group, making it a larger molecule. Some scientists believe<unk>  is too large to cross cellular membranes and must convert to NR before entering cells, where NAD+ biosynthesis occurs. Otherwise,<unk>  would need to be transported into cells by a transporter specific for<unk> , possibly such as Slc12a8. Both NR and<unk>  are vulnerable to extracellular degradation by CD38 enzyme, which can be inhibited by compounds such as CD38-IN-78c.
Nicotinamide mononucleotide
Uridine triacetate
Tetrahydrobiopterin
Sodium glycerophosphate
Histidine-tryptophan-ketoglutarate
Riboflavin
Neopterin
Inositol