This is a working overview of nicotinamide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-27 and is reviewed periodically as new material appears.
Beyond redox chemistry, NAD+ acts as a substrate for several enzyme families. ADP-ribosyltransferases, sirtuins, and CD38 ectoenzymes cleave the molecule into nicotinamide and ADP-ribose or related products. These reactions connect NAD+ availability to processes such as DNA repair, chromatin modification, and calcium signaling. Because the coenzyme is used in both electron transfer and signaling, cells maintain separate pools in compartments including the cytosol, mitochondria, and nucleus. The relative sizes and regulation of those pools remain active areas of study.
Cells produce NAD+ through several biosynthetic routes. The salvage pathway recycles nicotinamide, while the Preiss-Handler pathway uses nicotinic acid, and a de novo route can start from tryptophan in some organisms. In mammals, the salvage pathway is generally considered the main source under ordinary conditions. Tissue concentrations vary widely by cell type and compartment, and measured declines with age have been reported in some studies. Whether such changes drive aging or mainly accompany it remains an open question.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a coenzyme present in all living cells. The molecule consists of two nucleotides linked by phosphate groups, with adenine and a nicotinamide ring as its principal features. In its oxidized form, the nicotinamide ring can accept a hydride ion, becoming NADH. This reversible conversion places NAD+ at the center of many electron-transfer reactions. Its role as a redox carrier is well established across bacteria, plants, fungi, and animals.
Research on NAD+ often examines changes with age, diet, exercise, and disease states, but causal relationships are difficult to establish. Some studies measure NAD+ levels, while others assess enzyme activity or downstream markers. In the literature, terms such as "NAD+ decline" and "NAD+ boosting" appear in both scientific and commercial contexts, sometimes without precise definitions. Whether changes in measured NAD+ directly produce health effects remains an open question. Results from cells, animals, and humans cannot be assumed to translate directly.
Measuring NAD+ in biological samples requires rapid processing because the compound can degrade or interconvert after collection. Common approaches include enzymatic cycling assays, high-performance liquid chromatography, and mass spectrometry. Each method has different sensitivity, specificity, and susceptibility to interference from related nucleotides. Sample type matters: cultured cells, animal tissues, and human blood present distinct challenges. Reported values can vary widely across laboratories because of differences in extraction, normalization, and analytical platform. Standardization remains an open issue in the field.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C21H27N7O14P2 | Oxidized free acid form; charge depends on pH. |
| Molar mass | 663.43 g/mol | Calculated for the free acid. |
| CAS Registry Number | 53-84-9 | For the anhydrous free acid; salts have different identifiers. |
| Appearance | White to off-white powder | Solid material; hygroscopic. |
| Solubility | Water-soluble | Dissolves in aqueous buffers; solubility varies with pH and salt. |
The molecule was first described in the early twentieth century as a factor that promoted fermentation in yeast extracts. Later work linked it to hydrogen transfer and to the oxidation of nutrients in living tissues. Its structure was resolved as a dinucleotide, which explained why it could accept and donate electrons at specific enzyme sites. Today, NAD+ is recognized as a central substrate and signaling precursor, not merely a metabolic cofactor. Whether all observed NAD+ changes reflect causal signaling remains an open question.
Related compounds include NADH, the reduced form, and NADP+, which carries an additional phosphate group. NADP+ and NADPH often serve in biosynthetic and antioxidant reactions, while NAD+ and NADH are more associated with energy-yielding catabolism. Nicotinamide, nicotinic acid, and nicotinamide riboside are precursors that can enter salvage pathways. The exact contribution of dietary precursors to tissue NAD+ pools is an area of active investigation. Some studies measure labeled precursors to trace those routes.
Commercial NAD+ is available at research grade, often with purity specifications determined by high-performance liquid chromatography. Certificates of analysis may report water content, residual solvents, and counterion identity. Identity can be confirmed by ultraviolet absorbance near 260 nm, mass spectrometry, or enzymatic activity. Because different salt forms and hydration states exist, researchers should verify that the product matches the intended molecular form. Lot-to-lot variation in purity can affect quantitative assays and should be documented.
Solid NAD+ is usually supplied as a white to off-white powder or lyophilized preparation. It is hygroscopic and should be kept desiccated at low temperature, commonly -20 °C or below for long-term storage. Aqueous solutions are less stable than dry material and are often prepared fresh or stored frozen in aliquots. Light exposure and repeated freeze-thaw cycles can promote degradation, so amber containers and single-use aliquots are preferred. Buffered solutions near neutral pH are generally less stable than acidic or frozen preparations.
Commercial NAD+ is supplied as a solid, often as the free acid or a salt, and purity is verified by chromatographic methods. Laboratories typically store it desiccated at minus 20 degrees Celsius or below. Working solutions are prepared fresh because even sterile aqueous solutions can lose activity over hours to days depending on pH and temperature. Documentation may include a certificate of analysis, an assay value, and a recommended retest date. Researchers should verify identity and purity when results depend on precise cofactor concentrations.
NAD+ is commonly measured by high-performance liquid chromatography with ultraviolet detection, often at 254 or 260 nm. Enzymatic cycling assays provide higher sensitivity by coupling NAD+ to a reporter reaction. Mass spectrometry can distinguish NAD+ from close analogues and confirm isotope labeling. Sample preparation usually involves rapid quenching of metabolism to prevent interconversion with NADH. Because NAD+ and NADH differ by one hydride, extraction conditions strongly affect the measured ratio.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that transfer ADP-ribose or remove acetyl groups. Sirtuins, PARPs, and CD38-family enzymes consume NAD+ and produce nicotinamide and ADP-ribose-related products. These reactions link NAD+ availability to DNA repair, chromatin modification, and cellular signaling. Because the molecule is central to energy metabolism and regulation, changes in its concentration are studied in aging, immunity, and metabolic research. The balance between synthesis and consumption varies by tissue, developmental stage, and physiological state.
In humans, NAD+ can be synthesized from nicotinic acid, nicotinamide, nicotinamide riboside, and tryptophan through overlapping pathways. The salvage pathway recycles nicotinamide back to NAD+ and is often considered a major route in many tissues. Dietary precursors and intracellular recycling both contribute to the pool, but the quantitative importance of each source remains an active research question. NAD+ levels are not uniform across organs or cell compartments. Measurements in blood do not necessarily reflect concentrations inside tissues.
NAD+ is a dinucleotide composed of nicotinamide, ribose, and adenine linked by phosphate groups. Its full name is nicotinamide adenine dinucleotide, with "+" denoting the oxidized form. The molecule acts as a coenzyme in redox reactions, cycling between NAD+ and NADH. In cells, it participates in electron transfer during glycolysis, the citric acid cycle, and oxidative phosphorylation. It is distinct from NADP+, which carries an additional phosphate group and supports different biosynthetic reactions.
Chen, Li & Shi (2026) study the cranial morphology and phylogenetic affinities of Tossunnoria pseudibex, recover the species as a member of the bovid tribe Urmiatheriini, and interpret its caprin-like morphology as a result of convergent evolution. Revision of the type material of Pachygazella grangeri is published by Bai, Wang & Dong (2026). Evidence from the study of tooth wear of extant and Pleistocene springboks, indicative of variability of dietary signals in members of the same species both within and across different biomes, is presented by Walls et al. (2026). Dumitru et al. (2026) determine that deposition of fossils of Myotragus antiquus in Cova des Fum (Mallorca, Spain) happened between 3.60 and 3.45 million years ago, indicating that M. antiquus lived years earlier than indicated by previous estimates. Armaroli et al. (2026) provide new information on the late Pleistocene Alpine ibex population from Riparo Dalmeri (Italy) on the basis of the study of strontium, carbon and oxygen isotopic composition of their remains, ancient DNA data and radiocarbon dating, reporting evidence of stable density of the studied population despite intensive hunting and consistent human presence, as well as evidence dietary differences between sexes in the studied population. Sorbelli et al. (2026) describe fossil material of "Alephis" tigneresi from the Pliocene strata from Camp dels Ninots (Spain), and assign this species to the genus Parabos. Liang et al.
The first commercial oil well in Canada became operational in 1858 at Oil Springs, Ontario. Businessman James Miller Williams dug several wells between 1855 and 1858 before discovering a rich reserve of oil four metres below ground. Williams extracted 1.5 million litres of crude oil by 1860, refining much of it into kerosene lamp oil. Williams's well became commercially viable a year before Drake's Pennsylvania operation and could be argued to be the first commercial oil well in North America. The discovery at Oil Springs touched off an oil boom which brought hundreds of speculators and workers to the area. Advances in drilling continued into 1862 when local driller Shaw reached a depth of 62 metres using the spring-pole drilling method. On January 16, 1862, after an explosion of natural gas, Canada's first oil gusher came into production, shooting into the air at a recorded rate of 480 cubic metres (3,000 bbl) per day. By the end of the 19th century the Russian Empire, particularly the Branobel company in Azerbaijan, had taken the lead in production.
== Cited books == Mullenix, Matthew (2002). American Kestrels in Modern Falconry. Western Sporting Publications. ISBN 978-1-888357-05-9. Wauer, Roland H. (2005). The American kestrel: falcon of many names. Boulder, CO: Johnson Books. ISBN 978-1-55566-353-7.
Americium (95Am) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no known stable isotopes. The first isotope to be synthesized was 241Am in 1944. The artificial element decays by ejecting alpha particles. Americium has an atomic number of 95 (the number of protons in the nucleus of the americium atom). Despite 243Am being an order of magnitude longer lived than 241Am, the former is harder to obtain than the latter as more of it is present in spent nuclear fuel. Nineteen radioisotopes of americium, ranging from 229Am to 247Am have been characterized; another isotope, 223Am, has also been reported but is unconfirmed. The most stable isotopes are 243Am with a half-life of 7,350 years and 241Am with a half-life of 432.6 years. All of the remaining radioactive isotopes have half-lives that are less than seven days, the majority of which are shorter than two hours. This element also has fourteen meta states, with the most stable being 242m1Am (half-life 141 years). This isomer is unusual in that its half-life is far longer than that of the ground state of the same isotope.
=== Health === Differentiating healthy versus cancerous bladder cells with metabolic footprinting. Footprinting, in combination with other techniques, for early recognition of outbreak and strain characterization. Studying aging with C. elegans exometabolomics. Extracellular metabolite analysis to evaluate pathogenic mechanism of intracellular protozoal parasite.
Sources: en.wikipedia.org
== External links == Syria at Human Rights Watch Syria Charter of Rights and Freedoms Is a proposed modern system of human rights for adoption prior to a new Syrian constitution. 2010 Human Rights Report: Syria, U.S. Department of State, 8 April 2011 "Syria rights activist jailed for five years". Middle East Online. April 24, 2007. Archived from the original on September 28, 2007. Retrieved April 26, 2007. Uprising against the Assad Regime in Syria: Is This a Second Libya? June 2011, Qantara.de Worrall, James; Hightower, Victoria Penziner (2021). "Methods in the madness? Exploring the logics of torture in Syrian counterinsurgency practices". British Journal of Middle Eastern Studies. 49 (3): 418–432. doi:10.1080/13530194.2021.1916154. S2CID 234872905.
=== Movement === In addition to the formation of lamellipodia and filopodia, intracellular concentration and cross-talk between different Rho proteins drives the extensions and contractions that cause cellular locomotion. Sakumura et al. proposed a model based on differential equations that helps explain the activity of Rho proteins and their relationship to motion. This model encompassed the three proteins Cdc42, RhoA, and Rac. Cdc42 was assumed to encourage filopodia elongation and block actin depolymerization. RhoA was considered to encourage actin retraction. Rac was treated to encourage lamellipodia extension but block actin depolymerization. These three proteins, although significantly simplified, covered the key steps in cellular locomotion. Through various mathematical techniques, solutions to the differential equations that described various regions of activity based on intracellular activity were found. The paper concludes by showing that the model predicts that there are a few threshold concentrations that cause interesting effects on the activity of the cell. Below a certain concentration, there is very little activity, causing no extension of the arms and feet of the cell. Above a certain concentration, the Rho protein causes a sinusoidal oscillation much like the extensions and contractions of the lamellipodia and filopodia. In essence, this model predicts that increasing the intracellular concentration of these three key active Rho proteins causes an out-of-phase activity of the cell, resulting in extensions and contractions that are also out of phase.
=== Metaplasia === Metaplasia is not another definition of dedifferentiation, but the two words have very similar implications for cells. Metaplasia refers to the change from a fully differentiated cell type to another. This implies that the cell is able to adapt to environmental stimuli, and that it is possible to reverse embryological commitments in the form of differentiation. The idea of metaplasia depends on the ability for a cell to dedifferentiate. This definition is important to consider when discussing dedifferentiation because the two concepts overlap closely, such that metaplasia may rely on dedifferentiation, or they may share similar pathways. Metaplasia, however, aligns more closely with transdifferentiation, because metaplasia refers more to the idea of a phenotypic transition.
==== Monofloral ==== Monofloral honey is made primarily from the nectar of one type of flower. Monofloral honeys have distinctive flavors and colors because of differences between their principal nectar sources. To produce monofloral honey, beekeepers keep beehives in an area where the bees have access, as far as possible, to only one type of flower. In practice, a small proportion of any monofloral honey will be from other flower types. Typical examples of North American monofloral honeys are clover, orange blossom, sage, tupelo, buckwheat, fireweed, mesquite, sourwood, cherry, and blueberry. Some typical European examples include thyme, thistle, heather, acacia, dandelion, sunflower, lavender, honeysuckle, and varieties from lime and chestnut trees. In North Africa (e.g. Egypt), examples include clover, cotton, and citrus (mainly orange blossoms). The unique flora of Australia yields a number of distinctive honeys, with some of the most popular being yellow box, blue gum, ironbark, bush mallee, Tasmanian leatherwood, and macadamia. Mānuka honey, produced from the nectar of Leptospermum scoparium in New Zealand and parts of Australia, is darker in color and has an earthy, slightly bitter flavor profile compared with lighter honeys such as clover.
Sources: en.wikipedia.org
Additionally, when physicochemical properties or structures are expressed by numbers, one can find a mathematical relationship, or quantitative structure-activity relationship, between the two. The mathematical expression, if carefully validated, can then be used to predict the modeled response of other chemical structures. A QSAR has the form of a mathematical model:
The first element of the system is the amino acid that is added to the genetic code of a certain strain of organism. Over 71 different NSAAs have been added to different strains of E. coli, yeast or mammalian cells. Due to technical details (easier chemical synthesis of NSAAs, less crosstalk and easier evolution of the aminoacyl-tRNA synthase), the NSAAs are generally larger than standard amino acids and most often have a phenylalanine core but with a large variety of different substituents. These allow a large repertoire of new functions, such as labeling (see figure), as a fluorescent reporter (e.g. dansyl alanine) or to produce translational proteins in E. coli with Eukaryotic post-translational modifications (e.g. phosphoserine, phosphothreonine, and phosphotyrosine). The founding work was performed by Rolf Furter, who used the yeast tRNAPhe/PheRS pair to incorporate p-fluorophenylalanine in E. coli.
{\displaystyle p^{D}(r)={\begin{cases}-{\frac {\sigma _{0}}{\pi }}\cos ^{-1}\left[{\frac {2-m^{2}-{\frac {r^{2}}{a^{2}}}}{m^{2}\left(1-{\frac {r^{2}}{m^{2}a^{2}}}\right)}}\right]&\quad {\text{for}}\quad r\leq a\\-\sigma _{0}&\quad {\text{for}}\quad a\leq r\leq c\end{cases}}}
Consequently, the players were handed the full minimum suspensions of two years – these were backdated to 31 March 2015, which was the date of the original AFL Tribunal not guilty verdict; and, with credit taken for the periods of provisional suspension already served during the 2014/15 offseason, resulted in most of the suspensions running until November 2016.
Between 2007 and 2012, Mexico's National Human Rights Commission received nearly 5,800 complaints of military abuse and issued around 90 detailed reports documenting violations against civilians committed while the armed forces carried out policing duties. The Mexican military operated with minimal accountability for abuses committed in its campaigns.
Sources: en.wikipedia.org
NAD+ is a coenzyme found in living cells and is the oxidized form of nicotinamide adenine dinucleotide. It accepts electrons in redox reactions and also serves as a substrate for certain signaling and repair enzymes.
NAD+ becomes NADH when it accepts a hydride ion during oxidation-reduction reactions. NADH then donates electrons to other molecules, after which the carrier can return to the NAD+ form.
No, nicotinamide is a smaller molecule and a component of NAD+. Cells can use nicotinamide to rebuild NAD+ through the salvage pathway.
Researchers often use enzymatic cycling assays, liquid chromatography, or mass spectrometry. The choice depends on sample size, sensitivity needs, and available equipment. Because NAD+ can degrade quickly, rapid extraction and careful handling are important.