This is a working overview of NAD+, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-11 and is reviewed periodically as new material appears.
Nicotinamide mononucleotide, abbreviated NMN, is a naturally occurring nucleotide found in the cells of many organisms, including bacteria, plants, and mammals. Its structure consists of a nicotinamide ring attached to a ribose-phosphate group. NMN functions as an intermediate in the NAD+ salvage pathway, a recycling route that regenerates nicotinamide adenine dinucleotide. The enzyme nicotinamide phosphoribosyltransferase produces NMN from nicotinamide and phosphoribosyl pyrophosphate. A second enzyme, NMN adenylyltransferase, then converts NMN into NAD+.
Dietary sources of NMN include small amounts in certain vegetables, fruits, and other foods, although exact values vary by sample and method. Endogenous NMN concentrations are tightly regulated and often low, making measurement in blood or tissues technically demanding. After oral intake, NMN is thought to be rapidly metabolized in the intestine and liver, and intact NMN may not reach all tissues at high levels. Some rodent studies report increases in tissue NAD+ after oral NMN, while human data remain limited and sometimes rely on blood NAD+ metabolites rather than direct tissue measures.
Nicotinamide mononucleotide, commonly abbreviated NMN, is a pyridine nucleotide that consists of a nicotinamide ring, a ribose sugar, and a phosphate group. It is an intermediate in the salvage pathway for nicotinamide adenine dinucleotide, or NAD+, synthesis. In mammalian cells, the enzyme nicotinamide phosphoribosyltransferase produces NMN from nicotinamide and phosphoribosyl pyrophosphate. Nicotinamide mononucleotide adenylyltransferases then convert NMN into NAD+. The core structure and enzymatic route are well established in biochemical literature.
The biologically relevant form of NMN is generally the beta anomer, which is recognized by NMN adenylyltransferases. NMN is polar and water soluble, and it does not readily diffuse across lipid membranes without assistance. Whether intact NMN enters cells through a specific transporter remains an open question; some studies propose solute carrier family members, while other work favors extracellular dephosphorylation to nicotinamide riboside followed by uptake. This transport and compartmentalization debate affects how researchers interpret oral administration studies. The distinction between intracellular synthesis and extracellular delivery is central to current discussion.
| Property | Value | Notes |
|---|---|---|
| Chemical name | Nicotinamide mononucleotide | Nucleotide intermediate in NAD+ salvage pathway |
| Common abbreviation | NMN | Also written as β-NMN |
| Molecular formula | C11H15N2O8P | Uncharged parent form |
| Molar mass | 334.22 g/mol | Calculated from formula |
| CAS Registry Number | 1094-61-7 | For β-nicotinamide mononucleotide |
Nicotinamide mononucleotide, abbreviated NMN, is a naturally occurring nucleotide. Its structure combines a nicotinamide ring, a ribose sugar, and a phosphate group. The compound exists in cells as an intermediate in the production of nicotinamide adenine dinucleotide, a central redox cofactor. NMN is distinct from nicotinamide riboside, another related pyridine nucleotide, although the two compounds can converge in metabolic pathways. Its chemical formula is C11H15N2O8P, and it carries a net negative charge at physiological pH.
In the salvage pathway, NMN is generated from nicotinamide and 5-phosphoribosyl-1-pyrophosphate by the enzyme nicotinamide phosphoribosyltransferase. A second route produces NMN from nicotinamide riboside through phosphorylation by nicotinamide riboside kinases. NMN is then converted to NAD+ by nicotinamide mononucleotide adenylyltransferases, often called NMNAT enzymes. This stepwise route allows cells to recycle nicotinamide and maintain NAD+ levels under changing metabolic conditions. The relative contribution of each route varies by tissue, species, and physiological state, and it remains an active area of research.
In the canonical salvage pathway, nicotinamide phosphoribosyltransferase, known as NAMPT, transfers a phosphoribosyl group to nicotinamide and releases NMN. A second enzyme, NMN adenylyltransferase, then attaches an adenylyl group to NMN to form NAD+. Alternative routes exist, including a pathway that uses nicotinamide riboside and its phosphorylated forms. The relative contribution of extracellular NMN to intracellular NAD+ pools remains an area of active investigation, and the roles of specific transporters and enzymes are not completely defined.
NMN is present in small amounts in various foods, including certain vegetables, fruits, and milk, though dietary quantities are generally low. Laboratory research often uses synthetic or enzymatically produced NMN. The compound has drawn interest because NAD+ levels decline with age in some tissues and because restoring NAD+ may affect metabolism in animal models. Whether oral NMN produces meaningful NAD+ increases in humans and whether such changes translate into health benefits are not fully established.
A proton is a stable subatomic particle, symbol p, H+, or 1H+ with a positive electric charge of +1 e (elementary charge). Its mass is slightly less than the mass of a neutron and approximately 1836 times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one dalton, are jointly referred to as nucleons (particles present in atomic nuclei). One or more protons are present in the nucleus of every atom. They provide the attractive electrostatic central force which binds the atomic electrons. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol Z). Since each element is identified by the number of protons in its nucleus, each element has its own atomic number, which determines the number of atomic electrons and consequently the identity and chemical characteristics of the element. The word proton is Greek for "first", and the name was given to the hydrogen nucleus by Ernest Rutherford in 1920. In previous years, Rutherford had discovered that the hydrogen nucleus (known to be the lightest nucleus) could be extracted from the nuclei of nitrogen by atomic collisions. Protons were therefore a candidate to be a fundamental or elementary particle, and hence a building block of nitrogen and all other heavier atomic nuclei.
=== John-Daniel Stern === John-Daniel "JD" Stern (Adain Bradley) is Harper's estranged twin brother, who disappeared from her life when the two were teenagers. In series 2, Harper tracks down her brother to Berlin, where he works as a line cook. The two spend the night at a club, and the next morning, JD relapses on his meth addiction. The two have a vicious argument over their childhood growing up with an abusive mother; JD reveals he ran away in part due to Harper exacerbating the pressure their mother put on him to be a star tennis player, but Harper maintains that she too escaped a traumatic upbringing. Harper begs JD to come home with her, but rebuffs her, branding his sister a selfish narcissist who was complicit in the abuse he suffered. Harper is left deeply shaken by the encounter. In series 4, JD calls Harper to tell her that their mother died in a freak accident, having fallen down the stairs while collecting an Amazon delivery. Harper struggles to grieve her mother's death given her traumatic childhood, as well as her preoccupation with her work.
In the 19th century, artificial feeding begin to replace wet nursing, and by 1900, wet nursing no longer existed as an organized profession. Changes to the feeding of infants were both socially and technologically driven. With industrialization, more mothers worked outside the home and could less easily breastfeed their children. Technological changes including the design of artificial feeding methods and the preparation of animal milks and other milk substitutes supported a transition to artificial feeding, but with mixed success. Understanding of both nutrition and sanitation lagged behind the introduction of artificial feeding methods, contributing to extremely high infant mortality rates in the Victorian era.
Sources: en.wikipedia.org
The European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) (formerly EFCC) is a federation of national member societies of clinical chemistry and laboratory medicine from Europe. EFLM has its registered office in Brussels and its administrative office in Milan. EFLM is the European Regional member of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)
== Amine protection == Benzyl chloroformate is commonly used in organic synthesis for the introduction of the benzyloxycarbonyl (formerly called carboxybenzyl) protecting group for amines. The protecting group is abbreviated Cbz or Z (in honor of discoverer Zervas), hence the alternative shorthand designation for benzyl chloroformate as Cbz-Cl or Z-Cl. Benzyloxycarbonyl is a key protecting group for amines, suppressing the nucleophilic and basic properties of the N lone pair. This "reactivity masking" property, along with the ability to prevent racemization of Z-protected amines, made the Z group the basis of the Begmann-Zervas synthesis of oligopeptides (1932) where the following general reaction is performed to protect the N-terminus of a serially growing oligopeptide chain:
Diazepam is a long-acting "classical" benzodiazepine. Other classical benzodiazepines include chlordiazepoxide, clonazepam, lorazepam, oxazepam, nitrazepam, temazepam, flurazepam, bromazepam, and clorazepate. Diazepam has anticonvulsant properties. Benzodiazepines act via micromolar benzodiazepine binding sites as calcium channel blockers and significantly inhibit depolarization-sensitive calcium uptake in rat nerve cell preparations. Diazepam inhibits acetylcholine release in mouse hippocampal synaptosomes. This has been found by measuring sodium-dependent high-affinity choline uptake in mouse brain cells in vitro, after pretreatment of the mice with diazepam in vivo. This may play a role in explaining diazepam's anticonvulsant properties. Diazepam binds with high affinity to glial cells in animal cell cultures. Diazepam at high doses has been found to decrease histamine turnover in mouse brain via diazepam's action at the benzodiazepine-GABA receptor complex. Diazepam also decreases prolactin release in rats.
Sources: en.wikipedia.org
==== The Shipowner's house ==== From the 18th century; like the Museum of Old Havre it is dedicated to the History of Le Havre and contains many relics from the Ancien Régime as well as furniture, old maps, statues, and paintings.
van Heyningen, professor emeritus, University of Oxford, UK, and John R. Seal, former scientific director, National Institute of Allergy and Infectious Diseases, Bethesda, note that De's paper "deserves to go down as a classic in the history of cholera, and, indeed, as later developments have shown, in the history of cellular physiology and biochemistry." Thanks to De's discovery of the cholera enterotoxin, research has been redirected to find a vaccine that will spark the immune system to fight the enterotoxin specifically, rather than the bacteria. De and colleagues also published highly cited pioneering studies on V. cholerae action on the intestinal membrane.,, The 1953 paper “An experimental study of the mechanism of action of Vibrio cholerae on the intestinal mucous membrane” is De’s most-cited paper, cited 340 times until August 1986. It was especially influential on research fronts on "E. coli and Vibrio cholerae enterotoxin: detection, characterization, and role of adherence" and "Characterization of cholera enterotoxin and other enterotoxins". John Craig of State University of New York Health Science Center at Brooklyn described De’s work as truly creative and novel, having “forever altered our concepts surrounding the pathogenesis of secretory diarrhoea.” These findings resulted from work he conducted at the Nilratan Sircar Medical College, Calcutta Medical College, and Bose Institute in Kolkata. His research used relatively simple and inexpensive methods. In the words of Nobel Laureate Prof.
Per- and Polyfluoroalkyl Substances (PFAS) at the National Toxicology Program Per- and Polyfluoroalkyl Substances and Your Health at the Agency for Toxic Substances and Disease Registry Per- and Polyfluoroalkyl Substances (PFAS) at the EPA Per- and polyfluoroalkyl substances (PFASs) at the European Chemicals Agency PFAS contamination map of Europe Per- and Polyfluoroalkyl substances, National Institute for Occupational Safety and Health The Forever Pollution Project – Journalists tracking PFAS across Europe PFAS contamination in Queensland, Australia, State Library of Queensland "Contaminated: The Carpet Industry's Toxic Legacy". Frontline. Season 44. Episode 8. 3 February 2026. PBS. WGBH. Retrieved 25 February 2026.
Argiopine: contains 2,4-dihydroxyphenylacetic acid. It is also named Arg-636. Argiopinines: (4-hydroxyindol-3-yl) acetic acid is carried as the chromophore. These molecules are: Arg-630, Arg-658, Arg-659, Arg-744, Arg-759. Pseudoargiopinines: They contain a (indol-3-yl) acetic acid. This group is composed of: Arg-373, Arg-728, Arg-743.
Sources: en.wikipedia.org
NMN is nicotinamide mononucleotide, a nucleotide intermediate in the NAD+ salvage pathway. Cells use it to help regenerate NAD+, a coenzyme involved in energy metabolism and cellular signaling. It is present naturally in many organisms and is also produced synthetically for research and consumer products.
NMN is the immediate precursor to NAD+ in the salvage pathway. The enzyme NMN adenylyltransferase adds an adenylate group to NMN to form NAD+. Because NAD+ levels decline with age in some tissues, researchers study whether raising NMN availability can influence NAD+ metabolism.
No. Human evidence is limited, and no regulatory agency has approved NMN for treating or preventing aging. Some trials measure NAD+ metabolites or metabolic markers, but their results do not establish a clinical benefit. Larger, longer studies with standardized endpoints are needed.
NMN stands for nicotinamide mononucleotide. It is a naturally occurring nucleotide intermediate in NAD+ biosynthesis.