Niacinamide is an important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and PELLAGRA. Most animals cannot manufacture this compound in amounts sufficient to prevent nutritional deficiency and it therefore must be supplemented through dietary intake.
Nicotinamide strongly inhibits yeast silencing, increases rDNA recombination, and shortens replicative life span to that of a sir2 mutant. Nicotinamide abolishes silencing and leads to an eventual delocalization of Sir2 even in G(1)-arrested cells, demonstrating that silent heterochromatin requires continual Sir2 activity.  Nicotinamide results in a twofold increase in DNA content and a threefold increase in insulin content in the fetal cells. Nicotinamide induces differentiation and maturation of human fetal pancreatic islet cells.  Nicotinamide regulates sirtuins by switching between deacetylation and base exchange. Nicotinamide switching is quantitated for the Sir2s from Archeaglobus fulgidus (Sir2Af2), Saccharomyces cerevisiae (Sir2p), and mouse (Sir2alpha).  Nicotinamide selectively reduces a specific phospho-species of tau (Thr231) that is associated with microtubule depolymerization in Alzheimer's disease transgenic mice, in a manner similar to inhibition of SirT1. Nicotinamide also dramatically increases acetylated alpha-tubulin, a primary substrate of SirT2, and MAP2c in Alzheimer's disease transgenic mice, both of which are linked to increased microtubule stability.  Nicotinamide fosters DNA integrity and maintains phosphatidylserine membrane asymmetry to prevent cellular inflammation, cellular phagocytosis and vascular thrombosis. Nicotinamide both prevents and reverses neuronal and vascular cell injury. 
Normal and streptozotocin-nicotinamide induced adult male diabetic rats receive quercetin (10, 25 and 50 mg/kg/bw) orally, which results in a significant decrease in FBG and cardiac injury marker levels with increased insulin levels. Nicotinamide improves maternal hypertension, proteinuria, and glomerular endotheliosis in RUPP mice. Moreover, nicotinamide prolongs pregnancies, and improves survival and growth of the embryos in RUPP PE mice.