Everything below concerns Redox cofactor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-04-27. Where a claim depends on a specific study, the study is described rather than over-claimed.
Biosynthesis occurs through salvage, Preiss-Handler, and de novo pathways. In mammals, the salvage pathway from nicotinamide predominates, and NAMPT is often described as rate-limiting. Nicotinamide riboside and nicotinic acid enter related routes that converge on NAD+ production. Tissue NAD+ concentrations vary widely and are maintained by a balance of synthesis and consumption. Some studies report age-related declines in certain tissues, but whether these changes cause disease or can be reversed to improve human health remains an open question.
NAD+ stands for nicotinamide adenine dinucleotide, the oxidized form of a coenzyme found in all living cells. The molecule consists of two nucleotides, adenine and nicotinamide ribose, joined through phosphate groups. Its chemical formula is C21H27N7O14P2, and the free acid has a molar mass near 663.43 grams per mole. In redox reactions, NAD+ accepts a hydride ion and becomes NADH. The pair NAD+ and NADH participates in hundreds of metabolic reactions, including steps in glycolysis, the citric acid cycle, and oxidative phosphorylation.
In cells, NAD+ functions primarily as an electron carrier. Dehydrogenase enzymes in glycolysis and the citric acid cycle transfer hydride from substrates to NAD+, producing NADH. NADH then delivers electrons to the mitochondrial respiratory chain, supporting ATP synthesis. In fermentation, NADH is reoxidized to NAD+ so that glycolysis can continue. The balance between NAD+ and NADH helps set metabolic flux. Beyond redox, NAD+ serves as a substrate for enzymes that cleave it, including sirtuins, poly(ADP-ribose) polymerases, and CD38. These reactions consume NAD+ and release nicotinamide and ADP-ribose products.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C21H27N7O14P2 | Oxidized form; NADH adds a hydride equivalent. |
| Molar mass | 663.43 g/mol | Free acid form; salts have different values. |
| CAS Registry Number | 53-84-9 | Common identifier for beta-NAD. |
| Appearance | White to off-white powder | Hygroscopic; may absorb moisture from air. |
| Solubility | Freely soluble in water | Poorly soluble in most organic solvents. |
Quality control for NAD+ relies on identity, purity, and functional tests. A certificate of analysis may report high-performance liquid chromatography purity, ultraviolet spectrum, water content, and residual solvents. Because NAD+ is hygroscopic, gravimetric values can shift as material absorbs water, so purity should be interpreted alongside storage history. Mass spectrometry confirms molecular identity, while enzymatic assays show whether the material supports dehydrogenase activity. Commercial material is available as the free acid and as salts, and the counterion affects molecular weight, solubility, and how concentrations are calculated.
Laboratory measurement of NAD+ usually begins with rapid sample quenching because the molecule can change form after collection. Enzymatic cycling assays amplify signal through coupled reactions and are suited to small samples. High-performance liquid chromatography with ultraviolet detection separates NAD+ from related nucleotides. Liquid chromatography-mass spectrometry offers higher specificity and can distinguish NAD+ from close analogs. Each method has trade-offs in sensitivity, throughput, and equipment needs, so reported values depend heavily on extraction and detection choices.
Stability of NAD+ depends on form, temperature, pH, and water content. The solid is generally more stable than solutions, and it should be kept dry and cold. In solution, hydrolysis can cleave the dinucleotide, especially under alkaline conditions or at elevated temperature. Light exposure may also contribute to degradation. Buffers, chelating agents, and sterile handling can reduce losses, but no single condition preserves all preparations indefinitely. Researchers often prepare working solutions shortly before use and verify activity or purity after storage.
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.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer its ADP-ribose moiety or remove acetyl groups. Sirtuins consume NAD+ during deacetylation, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 enzymes hydrolyze it to signaling metabolites. These consumption pathways mean that NAD+ availability can influence gene regulation, DNA repair, and calcium signaling. Cellular NAD+ concentrations decline in some tissues with age in animal models, but whether this decline is a cause or consequence of aging in humans remains an active open question.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a dinucleotide coenzyme built from an adenine nucleotide and a nicotinamide nucleotide joined by a pyrophosphate linkage. Its oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, carries a hydride equivalent. The molecule participates in hundreds of oxidoreductase reactions, where it accepts or donates electrons and protons. Because it can cycle between oxidized and reduced states without net consumption, NAD+ functions as a reusable electron carrier rather than a fuel molecule.
Purified NAD+ is typically supplied as a white to off-white powder and stored desiccated at low temperature. Airtight containers limit moisture uptake, while protection from light reduces degradation of the nicotinamide ring. Aqueous stock solutions are less stable than solid material and are often aliquoted before freezing. Repeated freeze-thaw cycles can lower integrity, so working portions are kept separate. Purity is commonly checked by ultraviolet absorbance near 260 nm, high-performance liquid chromatography, or mass spectrometry.
Stability studies show that NAD+ can hydrolyze under prolonged heat, extreme pH, or microbial contamination. Phosphate buffers near neutral pH are often used for short-term handling, though exact stability depends on concentration, temperature, and matrix. In biological samples, endogenous enzymes can rapidly degrade NAD+, making cold chain and fast processing important. Analytical reports should state extraction conditions, internal standards, and validation parameters. Without those details, comparisons across studies remain difficult and potentially misleading.
A major hurdle to overcome is the long reaction time for complete rotation in these systems, which does not compare to rotation speeds displayed by motor proteins in biological systems. In the fastest system to date, with a fluorene lower half, the half-life of the thermal helix inversion is 0.005 seconds. This compound is synthesized using the Barton-Kellogg reaction. In this molecule the slowest step in its rotation, the thermally induced helix-inversion, is believed to proceed much more quickly because the larger tert-butyl group makes the unstable isomer even less stable than when the methyl group is used. This is because the unstable isomer is more destabilized than the transition state that leads to helix-inversion. The different behaviour of the two molecules is illustrated by the fact that the half-life time for the compound with a methyl group instead of a tert-butyl group is 3.2 minutes. The Feringa principle has been incorporated into a prototype nanocar. The car synthesized has a helicene-derived engine with an oligo (phenylene ethynylene) chassis and four carborane wheels and is expected to be able to move on a solid surface with scanning tunneling microscopy monitoring, although so far this has not been observed. The motor does not perform with fullerene wheels because they quench the photochemistry of the motor moiety. Feringa motors have also been shown to remain operable when chemically attached to solid surfaces. The ability of certain Feringa systems to act as an asymmetric catalyst has also been demonstrated.
In addition to the Hurricanes, the North Carolina FC of the United Soccer League Championship and North Carolina Courage of the National Women’s Soccer League play in suburban Cary to the west; the Carolina Mudcats, a Single-A minor-league baseball team, play in the city's eastern suburbs; the newly formed Single-A minor-league baseball Fayetteville Woodpeckers, who formerly played in Buies Creek, began play in the nearby out-of-county southern suburb of Fayetteville when their new ballpark opened in 2019; the Carolina Flyers of the American Ultimate Disc League play primarily at Cardinal Gibbons High School near the Lenovo Center; and the Durham Bulls, the AAA minor-league baseball team made internationally famous by the movie Bull Durham, play in the neighboring city of Durham. The Raleigh Firebirds of The Basketball League play at St. Augustine's University. Several other professional sports leagues have had former franchises (now defunct) in Raleigh, including the Raleigh IceCaps of the ECHL (1991–1998); Carolina Cobras of the Arena Football League (2000–2004); the Raleigh–Durham Skyhawks of the World League of American Football (1991); the Raleigh Bullfrogs of the Global Basketball Association (1991–1992); the Raleigh Cougars of the United States Basketball League (1997–1999); and most recently, the Carolina Courage of the Women's United Soccer Association (2000–2001 in Chapel Hill, 2001–2003 in suburban Cary), which won that league's championship Founders Cup in 2002.
== Insulin == Agonists: Chaetochromin (4548-G05) Insulin-like growth factor 1 Insulin-like growth factor 2 Insulin Insulin aspart Insulin degludec Insulin detemir Insulin glargine Insulin glulisine Insulin lispro Mecasermin Mecasermin rinfabate Antagonists: BMS-754807 S661 S961 Kinase inhibitors: Linsitinib Antibodies: Xentuzumab (against IGF-1 and IGF-2)
== History == The oxymetazoline brand Afrin was first sold as a prescription medication in 1966. After finding substantial early success as a prescription medication, it became available as an over-the-counter drug in 1975. Schering-Plough did not engage in heavy advertising until 1986.
== Nomenclature == This enzyme belongs to the family of oxidoreductases, specifically those acting on CH or CH2 groups with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate:NAD(P)+ 4-oxidoreductase. Other names in common use include:
Sources: en.wikipedia.org
Natural viral diseases, such as myxomatosis and rabbit hemorrhagic disease, have been used to help control pest populations. Over time the surviving pests become resistant, leading researchers to look at alternative methods. Genetically modified viruses that make the target animals infertile through immunocontraception have been created in the laboratory as well as others that target the developmental stage of the animal. There are concerns with using this approach regarding virus containment and cross species infection. Sometimes the same virus can be modified for contrasting purposes. Genetic modification of the myxoma virus has been proposed to conserve European wild rabbits in the Iberian peninsula and to help regulate them in Australia. To protect the Iberian species from viral diseases, the myxoma virus was genetically modified to immunize the rabbits, while in Australia the same myxoma virus was genetically modified to lower fertility in the Australian rabbit population. Outside of biology scientists have used a genetically modified virus to construct a lithium-ion battery and other nanostructured materials. It is possible to engineer bacteriophages to express modified proteins on their surface and join them up in specific patterns (a technique called phage display). These structures have potential uses for energy storage and generation, biosensing and tissue regeneration with some new materials currently produced including quantum dots, liquid crystals, nanorings and nanofibres.
American banker and amateur ethnomycologist R. Gordon Wasson and his wife, Valentina P. Wasson, a physician, studied the ritual use of psychoactive mushrooms by the native population in the Mazatec village Huautla de Jiménez, Mexico. In 1957, Wasson described the psychedelic visions he experienced during these rituals in "Seeking the Magic Mushroom", an article published in the American weekly Life magazine. Later the same year they were accompanied on a follow-up expedition by French mycologist Roger Heim, who identified several of the mushrooms as Psilocybe species. Heim cultivated the mushrooms in France and sent samples for analysis to Albert Hofmann, a chemist employed by the Swiss pharmaceutical company Sandoz. Hofmann—who had synthesized lysergic acid diethylamide (LSD) in 1938—led a research group that isolated and identified the psychoactive alkaloids psilocybin and psilocin from Psilocybe mexicana, publishing their results in 1958. The team was aided in the discovery process by Hofmann's willingness to ingest mushroom extracts to help verify the presence of the active compounds. Next, Hofmann's team synthesized several structural analogs of these compounds to examine how these structural changes affect psychoactivity. This research led to the development of ethocybin and CZ-74. Because these compounds' physiological effects last only about three and a half hours (about half as long as psilocybin's), they proved more manageable for use in psycholytic therapy.
Sherrill's methods and algorithms are made publicly available to the quantum chemistry community through the open-source quantum chemistry program Psi, developed by his group and collaborators worldwide.
== Signals and noise == One of the most important components of analytical chemistry is maximizing the desired signal while minimizing the associated noise. The analytical figure of merit is known as the signal-to-noise ratio (S/N or SNR). Noise can arise from environmental factors as well as from fundamental physical processes.
As the Southern Operations Room advanced in the suburbs of Damascus, the Syrian Free Army was reported closing in on the capital from the north, after taking control of Palmyra, as well as Darayya. The Republican Guard, traditionally tasked with protecting the Syrian government, did not organize any defenses of Damascus and offered no resistance to the rebel advances. According to The Guardian, videos showed Syrian police and army forces removing their uniforms in the streets of Damascus and an Associated Press journalist reported seeing armed residents along the roads in Damascus's outskirts and finding the city's main police headquarters abandoned. Tank movements were reported in central squares of the capital, while calls of "God is great" rang out from mosques. Even as the situation in Damascus deteriorated, Assad reportedly pretended to work as usual, though he made no effort to organize a last stand or publicly inspire confidence among his loyalists. Syrian state media officially denied allegations that he had fled the capital. In the evening, Assad met with thirty army and security chiefs at the Ministry of Defense, and urged them to keep resisting the insurgents as Russian support was on its way. At 10:30 pm, the president received a phone call by his prime minister Mohammad Ghazi al-Jalali who informed him that the government's situation had further declined, with large numbers of refugees fleeing from Homs toward Latakia. Assad just told him "Tomorrow, we will see. Tomorrow, tomorrow," ending the call.
Sources: en.wikipedia.org
Venezuela has been a path to the United States and Europe for illegal drugs originating in Colombia, through Central America, Mexico and Caribbean countries such as Haiti, the Dominican Republic, and Puerto Rico. According to the United Nations, cocaine trafficking through Venezuela increased from 2002 to 2008. In 2005, the government of Hugo Chávez severed ties with the United States Drug Enforcement Administration (DEA), accusing its representatives of spying. Following the departure of the DEA from Venezuela and the expansion of the DEA's partnership with Colombia in 2005, Venezuela became more attractive to drug traffickers. Between 2008 and 2012, Venezuela's cocaine seizure ranking among other countries declined, going from being ranked fourth in the world for cocaine seizures in 2008 to sixth in the world in 2012. On 18 November 2016, following what was known as the Narcosobrinos incident, Venezuelan President Nicolás Maduro's two nephews were found guilty of trying to ship drugs into the United States so they could "obtain a large amount of cash to help their family stay in power". According to a research conducted by the Israel-based Abba Eban Institute as part of an initiative called Janus Initiative, the main routes that Hezbollah uses for smuggling drugs are from Colombia, Venezuela and Brazil into West Africa and then transported through northern Africa into Europe. This route serves Hezbollah in making a profit in the cocaine smuggling market in order to leverage it for their activities. In September 2025, the U.S.
== Properties == This compound is a yellow crystalline powder with moderate human toxicity. It shows two polymorphs in the crystalline state. The alpha-form is colorless pillars, unstable at room temperature, and stable toward sunlight. The beta-form is yellow pillars, stable at room temperature, and gradually turns red upon irradiation of sunlight. Usually 4-nitrophenol exists as a mixture of these two forms.
==== Australia ==== In Australia, both pure dextropropoxyphene capsules (as napsylate, 100 mg), marketed as Doloxene, and combination tablets and capsules (with paracetamol) all containing 32.5 mg dextropropoxyphene HCl with 325 mg paracetamol, which are currently available on prescription were supposed to be withdrawn from 1 March 2012, but Aspen Pharma sought a review in the Administrative Appeals Tribunal which ruled in 2013 that the drugs could be sold under strict conditions.
In August 2008, Obama and Biden met in secret to discuss the possibility of a place for Biden in the Obama administration, and developed a strong personal rapport. On August 22, Obama announced that Biden would be his running mate. The New York Times reported that the choice reflected a desire for someone with foreign policy and national security experience. Others pointed out Biden's appeal to middle-class and blue-collar voters. Biden was officially nominated for vice president on August 27 at the 2008 Democratic National Convention in Denver. Biden's vice-presidential campaigning gained little media attention, as the press devoted far more coverage to the Republican nominee and then-governor of Alaska, Sarah Palin. Under instructions from the campaign, Biden kept his speeches succinct and tried to avoid offhand remarks. Privately, Biden's remarks frustrated Obama. "How many times is Biden gonna say something stupid?", he once angrily asked. Obama campaign staffers called Biden's blunders "Joe bombs" and kept Biden uninformed about strategy discussions, which irked Biden. Relations between the two campaigns became strained for a month, until Biden apologized to Obama and the two built a stronger partnership. As the 2008 financial crisis reached a peak in September 2008, and the proposed Emergency Economic Stabilization Act of 2008 became a major factor in the campaign, Biden voted for the $700 billion Emergency Economic Stabilization Act of 2008, which passed in the Senate.
Sources: en.wikipedia.org
Nicotinamide adenine dinucleotide, with the plus sign indicating the oxidized form. It is a coenzyme present in all living cells. The reduced form is NADH.
No. NAD+ is oxidized and accepts electrons, while NADH is reduced and carries them. Together they form a redox pair central to energy metabolism.
NAD+ itself is not a common dietary component in significant amounts. Precursors such as nicotinamide, nicotinic acid, and nicotinamide riboside can be converted through biosynthetic pathways. Direct absorption of intact NAD+ is limited.
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.