生物活性

• 描述There are two types of enzymes that affect the acetylationstate of histones: histone acetyltransferases and the opposinghistone deacetylases (HDACs). Yeast silent information regulator 2 (Sir2) is the founding member of Class III HDACs. Nonredox enzyme, sirtuin 1 (Sirt1) is an important member of the mammalian sirtuin family of proteins that commonly have dual activities as a nicotinamide adenine dinucleotide (NAD⁺)- dependent deacetylase and as a mono-ADP ribosyltransferase. Nicotinamide (NAM), a form of vitamin B3, is an inhibitor of yeast Sir2 and human Sirt1 with IC₅₀ < 50 μM. Treatment of the fetal cells with 10 mM NIC resulted in a twofold increase in DNA content and a threefold increase in insulin content and induced differentiation and maturation of human fetal pancreatic islet cells. Nicotinamide incubation (5 mM) 2h prior to hypoxia significantly increased total nicotinamide adenine dinucleotide (NADH) content, improved neuronal recovery, enhanced ATP content, and prevented NADH hyperoxidation in hippocampal slices. It was found that nicotinamide (200 mg/kg/day) treatment in Alzheimer's disease transgenic mice-drinking water from birth until 4 months of age improved both the short- and long term memory.
• 作用机制Nicotinamide inhibits deacetylation by binding to a conserved pocket adjacent to NAD⁺.

• 动物研究
  剂量	Rat: 1260 mg/kg[3] (p.o.); 50 mg/kg, 500 mg/kg[4] (i.p.)
  给药途径	p.o., i.p.