Purify NMN by passage through a column of Dowex-1 (Cl- form) and washing with H2O until no absorbance is observed at 260 nm. The tubes containing NMN are pooled, adjusted to pH 5.5-6 and evaporated in vacuo to a small volume. This is adjusted to pH 3 with dilute HNO3 in an ice-bath and treated with 20volumes of Me2CO at 0-5o. The heavy white precipitate is collected by centrifugation at 0o. It is best stored wet and frozen or it can be dried to give a gummy residue. It has max 266nm ( 4,600) and min 249nm ( 3600) at pH 7.0 (i.e. no absorption at 340nm). It can be estimated by reaction with CN- or hydrosulfite which form the 4-adducts (equivalent to NADH) which have UV max 340nm ( 6,200). Thus after reaction, an OD340 of one is obtained from a 0.1612mM solution in a 1cm path cuvette. [Plaut & Plaut Biochemical Preparations 5 56 1957, Maplan & Stolzenbach Methods Enzymol 3 899 1957, Kaplan et al. J Am Chem Soc 77 815 1955, Beilstein 22/2 V 168.]
A product of the extracellular Nicotinamide phosphoribosyltransferase (eNAMPT) reaction and a key NAD+ intermediate. It ameliorates glucose intolerance by restoring NAD+ levels in HFD-induced T2D mice
. It also enhances hepatic insulin sensitivity and restores gene expression related to oxidative stress, inflammatory response, and circadian rhythm, partly through SIRT1 activation.