The short version of NAD+ fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-01-30 and is reviewed periodically as new material appears.
In glycolysis, NAD+ accepts electrons during the oxidation of glyceraldehyde-3-phosphate, forming NADH. The tricarboxylic acid cycle and fatty acid oxidation also generate NADH, which donates electrons to the mitochondrial electron transport chain. This flow supports ATP synthesis and helps maintain the redox balance of the cell. Other dehydrogenases use NAD+ as a cofactor for biosynthetic reductions and detoxification reactions. NADH is later reoxidized to sustain continued flux through these pathways.
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer ADP-ribose units. Sirtuins, poly(ADP-ribose) polymerases, and CD38 consume NAD+ in regulatory reactions. These activities link NAD+ availability to DNA repair, chromatin modification, calcium signaling, and metabolic stress responses. Because consumption can exceed biosynthesis under some conditions, cellular NAD+ levels are dynamic rather than fixed. Enzyme affinity and local synthesis also influence how much NAD+ is available for signaling.
NAD+ is a dinucleotide composed of adenine, ribose, and nicotinamide moieties linked by phosphate groups. Its oxidized form carries a positive charge on the nicotinamide ring, which enables reversible hydride transfer. The molecule functions as a coenzyme in oxidoreductase reactions rather than as a dietary vitamin in its intact form. Cells maintain separate pools in cytoplasm, mitochondria, and nucleus. This compartmentalization allows distinct redox environments while preserving a shared chemical identity.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical name | Nicotinamide adenine dinucleotide | Oxidized form abbreviated NAD+ |
| Molecular formula | C21H27N7O14P2 | Free acid form |
| Molar mass | 663.43 g/mol | Calculated for free acid |
| CAS Registry Number | 53-84-9 | Common entry for beta-NAD+ |
| Appearance | White to off-white powder | Hygroscopic solid |
In redox reactions, NAD+ accepts a hydride ion, which consists of two electrons and one proton. The hydride adds to the nicotinamide ring at a specific carbon, converting NAD+ into NADH. Dehydrogenase enzymes use this step in glycolysis, the citric acid cycle, and fatty acid oxidation. NADH later donates electrons to the mitochondrial electron transport chain, helping to drive ATP synthesis. The balance between NAD+ and NADH reflects the metabolic state of a cell, and shifts in that balance can alter how pathways operate.
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave it and attach its ADP-ribose portion to other molecules. This group includes poly(ADP-ribose) polymerases, CD38, and sirtuins. Such reactions consume NAD+ and can influence its availability for metabolism. Cells replenish NAD+ through a salvage pathway that recycles nicotinamide and through routes starting from tryptophan or vitamin B3 forms. How these synthesis and consumption routes are coordinated across tissues remains an active area of study, and compartment-specific concentrations are difficult to measure directly.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide built from adenine, nicotinamide, two ribose sugars, and two phosphate groups. The oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, is neutral. This pair acts as a reversible electron carrier in cells. NAD+ is present in bacteria, plants, animals, and fungi. Its structure allows it to accept and donate electrons without being consumed in the reactions it supports.
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.
NAD+ is the oxidized form of nicotinamide adenine dinucleotide, a coenzyme built from two nucleotides joined by a phosphate linkage. One nucleotide carries adenine, and the other carries nicotinamide; the plus sign denotes a formal positive charge on the nicotinamide ring, not a free proton. In cells, NAD+ and its reduced partner NADH form a reversible redox pair. That pair participates in electron transfer reactions throughout metabolism. The abbreviation NAD+ is common in biochemistry, while NAD(H) sometimes denotes the combined pool.
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.
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.
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.
Honey is a sweet and viscous substance made by several species of bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primarily floral nectar) or the secretions of other insects, like the honeydew of aphids. This refinement takes place both within individual bees, through regurgitation and enzymatic activity, and during storage in the hive, through water evaporation that concentrates the honey's sugars until it is thick and viscous. Honey bees stockpile honey in the hive. Within the hive is a structure made from beeswax called honeycomb. The honeycomb is made up of hundreds or thousands of hexagonal cells, into which the bees regurgitate honey for storage. Other honey-producing species of bee store the substance in different structures, such as the pots made of wax and resin used by the stingless bee. Honey for human consumption is collected from wild bee colonies, or from the hives of domesticated bees. The honey produced by honey bees is the most familiar to humans, thanks to its worldwide commercial production and availability. The husbandry of bees is known as beekeeping or apiculture, with the cultivation of stingless bees usually referred to as meliponiculture. Honey is sweet because of its high concentrations of the monosaccharides fructose and glucose. It has about the same relative sweetness as sucrose (table sugar). One standard tablespoon (14 mL) of honey provides around 180 kilojoules (43 kilocalories) of food energy.
The term málà is a combination of two Chinese characters: "numbing" (麻) and "spicy (piquant)" (辣), referring to the feeling in the mouth after eating the sauce. The numbness is caused by its characteristic Sichuan pepper, which contains 3% hydroxy-alpha-sanshool.
=== Research === 1ST-103 – undefined mechanism of action [140] LXM-5 – undefined mechanism of action [141] Parkinson's disease siRNA therapeutic - Argo Biopharma – RNA interference [142] Research programme: Parkinson's disease therapeutics - Beech Tree Labs (PD-A) – undefined mechanism of action – parkinsonian disorders [143]
Sources: en.wikipedia.org
== Types == Fomentations – heated poultices – may be used to promote blood circulation to an affected area; these may be unmedicated. Cold poultices are sometimes used. An example is the use of cabbage leaves to reduce breast engorgement in breastfeeding mothers. The leaves are applied directly to the breast, often simply held in place by a bra. Evidence for effectiveness as a treatment is weak: cabbage poultices are about as effective as the frequent, unrestricted feeding of the infant; they have no effect on the rate of progression to mastitis. There is some slight evidence that cabbage poultices reduce the pain of engorgement.
== History == Polymers have been essential components of commodities since the early days of humankind. The use of wool (keratin), cotton and linen fibres (cellulose) for garments, paper reed (cellulose) for paper are just a few examples of how ancient societies exploited polymer-containing raw materials to obtain artefacts. The latex sap of "caoutchouc" trees (natural rubber) reached Europe in the 16th century from South America long after the Olmec, Maya and Aztec had started using it as a material to make balls, waterproof textiles and containers. The chemical manipulation of polymers dates back to the 19th century, although at the time the nature of these species was not understood. The behaviour of polymers was initially rationalised according to the theory proposed by Thomas Graham which considered them as colloidal aggregates of small molecules held together by unknown forces. Notwithstanding the lack of theoretical knowledge, the potential of polymers to provide innovative, accessible and cheap materials was immediately grasped. The work carried out by Braconnot, Parkes, Ludersdorf, Hayward and many others on the modification of natural polymers determined many significant advances in the field. Their contributions led to the discovery of materials such as celluloid, galalith, parkesine, rayon, vulcanised rubber and, later, Bakelite: all materials that quickly entered industrial manufacturing processes and reached households as garments components (e.g., fabrics, buttons), crockery and decorative items.
== Exhibition == Lindow Man is held in the collection of the British Museum in London, where his remains were first publicly displayed in July 1986 as part of the exhibition Archaeology in Britain. In 1997, they were moved to the museum's Iron Age gallery. His remains have also been loaned to other museums for temporary exhibitions. Manchester Museum displayed him in 1987, 1991 and from 19 April 2008 to 19 April 2009. The 2008–2009 exhibition, Lindow Man: A Bog Body Mystery, won the award for Best Archaeological Innovation at the 2010 British Archaeological Awards. His remains were subsequently exhibited at the Great North Museum in Newcastle upon Tyne from August to November 2009, before returning to the British Museum.
By 1984, all public water was to be tested by using a GC/MS apparatus. In the 1980s, an estimated 60-70% of Finnigan's GC/MS sales went to the environmental market. GC/MS technology, of which Finnigan Instrument Corporation's instrument was the first, was the technical underpinning that made it possible for the EPA to carry out its regulatory efforts in the 1970s. About 100 organic compounds could be identified in water prior to 1970. By 1975, nearly 1500 organic pollutants had been identified. Without the ability to detect such compounds, their monitoring and regulation would not have been possible. In 1981, Finnigan purchased the MAT division from Varian Associates which produced mass spectrometers in Bremen, Germany forming the Finnigan MAT brand of MS instruments. When Finnigan Instrument Corporation was acquired by Thermo Instrument Systems (since 2006 Thermo Fisher Scientific) in 1990, the firm was considered "the world's leading manufacturer of mass spectrometers". Robert Finnigan continued to consult for the company for several years after the acquisition. He has also consulted with other entrepreneurial companies.
Sources: en.wikipedia.org
== Pathology == Saccharopinuria (high amounts of saccharopine in the urine) and saccharopinemia (an excess of saccharopine in the blood) are conditions present in some inherited disorders of lysine degradation.
===== Digital wallet scheme ===== Paetongtarn has overseen the implementation of the 10,000-baht digital wallet scheme, the flagship economic policy of the Pheu Thai Party. The scheme was originally promised during the 2023 election campaign as a one-time universal handout to nearly all Thais aged 16 and over, intended to deliver a large-scale stimulus to the domestic economy. However, since the Paetongtarn government took office, the program has faced significant modifications, delays, and criticism regarding its funding, implementation, and economic necessity. The initial plan to fund the 500 billion baht scheme through a special loan bill was scrapped due to legal concerns and fears of violating fiscal discipline laws. Instead, the government has relied on the national budget. The universal nature of the handout was also curtailed, with eligibility restrictions introduced to exclude high-income earners (those with an annual income over 840,000 baht) and individuals with more than 500,000 baht in savings. Phase 1, launched in September 2024, provided 10,000 baht in cash to approximately 14.5 million recipients, including state welfare cardholders and individuals with disabilities. Phase 2, implemented between January and April 2025, extended the cash transfers to an estimated 3 million senior citizens aged 60 and over. The first truly "digital" phase, which was set to target around 2.7 million young people aged 16–20 via a government application, has been indefinitely postponed.
Amphiphytes: plants that are adapted to live either submerged or on land Elodeids: stem plants that complete their entire lifecycle submerged, or with only their flowers above the waterline Isoetids: rosette plants that complete their entire lifecycle submerged Helophytes: plants rooted in the bottom, but with leaves above the waterline Nymphaeids: plants rooted in the bottom, but with leaves floating on the water surface Neuston: vascular plants that float freely in the water
centromeric index The proportion of the total length of a chromosome encompassed by its short arm, typically expressed as a percentage; e.g. a chromosome with a centromeric index of 15 is acrocentric, with a short arm comprising only 15% of its overall length.
=== Pain === Morphine is used primarily to treat both acute and chronic severe pain. Its duration of analgesia is about three to seven hours. Side effects of nausea and constipation are rarely severe enough to warrant stopping treatment. It is used for pain due to myocardial infarction and for labor pains. However, concerns exist that morphine may increase mortality in the event of non-ST elevation myocardial infarction. Morphine has also traditionally been used in the treatment of acute pulmonary edema. However, a 2006 review found little evidence to support this practice. A 2016 Cochrane review concluded that morphine is effective in relieving cancer pain.
Sources: en.wikipedia.org
NAD+ is the oxidized form, while NADH is the reduced form carrying an additional hydride equivalent. The pair participates in reversible electron transfer reactions. Their ratio helps indicate the redox state of a compartment.
NAD+ itself is not classified as a vitamin, but its precursor niacin is an essential nutrient in humans. Cells synthesize NAD+ from niacin, nicotinamide, nicotinamide riboside, or tryptophan. The intact dinucleotide is not obtained directly from typical diets in meaningful amounts.
Age-related studies often examine whether NAD+ levels decline in tissues and whether that decline affects mitochondrial function or DNA repair. Interventions using precursor molecules raise open questions about cause and effect. Current evidence does not establish that changing NAD+ levels slows human aging.
Common methods include enzymatic cycling assays, HPLC with UV detection, and LC-MS. The choice depends on sample size, specificity needs, and available equipment. Rapid quenching before analysis is important because NAD+ and NADH can interconvert.