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 2026-05-14 and is reviewed periodically as new material appears.
In aqueous solution, NAD+ is most stable under mildly acidic to neutral conditions and degrades faster at high pH or elevated temperature. The molecule can hydrolyze at the pyrophosphate bond or undergo nonenzymatic cyclization. Buffers, chelating agents, and cold temperatures slow these losses during analysis. Repeated freeze-thaw cycles are generally avoided because they can promote degradation and concentration changes. Light exposure is also controlled, though NAD+ is less photolabile than some related nucleotides.
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.
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.
| Property | Value | Notes |
|---|---|---|
| UV absorption maximum | 259–260 nm | Aqueous solution; pH-dependent |
| Common salt form | Disodium salt | Improves aqueous solubility |
| Typical storage temperature | -20 °C or lower | Desiccated and protected from light |
| Common analytical method | HPLC with UV detection | Often paired with mass spectrometry |
| Aqueous stability | pH and temperature dependent | Degrades faster at alkaline pH and high heat |
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 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.
NAD+ also serves as a substrate for enzymes that cleave it, including sirtuins, PARPs, and CD38. These enzymes consume NAD+ and release nicotinamide and ADP-ribose or related products. The dual roles as redox cofactor and signaling substrate connect NAD+ to DNA repair, circadian regulation, and calcium signaling. Cellular NAD+ concentrations vary by tissue, time of day, and stress exposure. How these consumption pathways interact with redox balance remains an active area of research.
NAD+ is a dinucleotide composed of two nucleotides joined by a pyrophosphate linkage. One nucleotide contains adenine, and the other contains nicotinamide. The oxidized form carries a positive charge on the nicotinamide ring and is abbreviated NAD+. It functions as a cofactor in hydride-transfer reactions, accepting electrons in catabolic pathways. In cells, it interconverts with reduced NADH, forming a redox couple central to energy metabolism. The molecule is water-soluble and does not cross cell membranes freely without specific transport or precursor pathways.
Beyond redox chemistry, NAD+ is consumed as a substrate by enzymes that transfer ADP-ribose or remove acetyl groups. Sirtuins use NAD+ in deacylation reactions, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 hydrolases convert it to signaling metabolites. Because these enzymes compete for the same pool, changes in NAD+ availability can influence multiple cellular processes. The relative contribution of each consumption route differs by cell type and condition, and precise quantitative links remain an active area of study.
Research on NAD+ spans biochemistry, aging biology, and metabolism. Studies often examine how NAD+ levels change with age, diet, exercise, or disease states, and whether precursor supplementation alters those levels. Findings in animal models do not automatically translate to humans, and measurement methods vary across studies. Questions about tissue-specific effects, long-term consequences, and causal relationships remain open. NAD+ itself is not established as a single therapeutic agent with a broad clinical role.
==== Agitation ==== Ketamine is used to treat acute agitation, aggression, and excited delirium in pre-hospital and emergency settings, including symptoms refractory to other drugs such as antipsychotics and benzodiazepines.
==== Australia and New Zealand ==== Australia and New Zealand published nutrient reference values including guidelines for dietary vitamin D intake in 2006. About a third of Australians have vitamin D deficiency.
== Medical uses == Uses include for fungal infections of the foot, impetigo, pemphigus, superficial wounds, dermatitis (eczema), and tropical ulcers. Typically it is used in skin conditions that produce a lot of liquid. For tropical ulcers it is used together with procaine benzylpenicillin for two to four weeks. It can be used in children and adults. It can be applied as a soaked dressing or a bath. Petroleum jelly may be used on the nails before soaking to prevent their discoloration. The U.S. Food and Drug Administration does not recommend its use in either the crystal or tablet form.
=== DNA repair and replication === In chloroplasts of the moss Physcomitrella patens, the DNA mismatch repair protein Msh1 interacts with the recombinational repair proteins RecA and RecG to maintain chloroplast genome stability. In chloroplasts of the plant Arabidopsis thaliana the RecA protein maintains the integrity of the chloroplast's DNA by a process that likely involves the recombinational repair of DNA damage.
Outside Romania, public audiences in Western Europe initially projected generally idealistic notions of revolution on the country; the legacies of the French Revolution were fresh on people's minds in 1989 during its two-hundredth anniversary. However, as violence continued into 1990 and reports reached the West of mass casualties, this projected narrative shifted into a less sympathetic one characterized by disappointment in and suspicion of the revolution's direction.
Sources: en.wikipedia.org
Dextrose monohydrate is the hydrated form of D-glucose, meaning that it is a glucose molecule with an additional water molecule attached. Its chemical formula is C6H12O6 · H2O. Dextrose monohydrate is also called hydrated D-glucose, and commonly manufactured from plant starches. Dextrose monohydrate is used as the predominant type of dextrose in food applications, such as beverage mixes—it is a common form of glucose widely used as a nutrition supplement in production of foodstuffs. Dextrose monohydrate is primarily consumed in North America as a corn syrup or high-fructose corn syrup. Anhydrous dextrose, on the other hand, is glucose that does not have any water molecules attached to it. Anhydrous chemical substances are commonly produced by eliminating water from a hydrated substance through methods such as heating or drying up (desiccation). Dextrose monohydrate can be dehydrated to anhydrous dextrose in industrial setting. Dextrose monohydrate is composed of approximately 9.5% water by mass; through the process of dehydration, this water content is eliminated to yield anhydrous (dry) dextrose. Anhydrous dextrose has the chemical formula C6H12O6, without any water molecule attached which is the same as glucose. Anhydrous dextrose on open air tends to absorb moisture and transform to the monohydrate, and it is more expensive to produce. Anhydrous dextrose (anhydrous D-glucose) has increased stability and increased shelf life, has medical applications, such as in oral glucose tolerance test.
Mean Green – Big, bold flavor inspired by the original black and green Monster Energy can. White Haze – A smooth, citrusy flavor with a clean finish. Peach Perfect – A crisp and refreshing peach blend. Scary Berries – A sparkling citrus and berry mix with less sweetness. Killer Sunrise – A bold citrus punch designed for all-day partying. Gnarly Grape – A juicy grape flavor with a bold finish. Pink Poison – A sweet and tangy blend with a vibrant profile. Later in 2023, Monster introduced the Nasty Beast line, a series of hard iced tea beverages targeting the flavored malt beverage market and competing with brands like Twisted Tea. Like The Beast Unleashed, these contain 6.0% ABV. Nasty Beast flavors include:
Doillon started acting at age five, starring in Kung Fu Master directed by Agnès Varda. She has since worked with directors including Jean Pierre Améris, Jacques Doillon, Guillaume Canet, Abel Ferrara and Maïwenn.
Cysteine is similarly produced, namely it can be made from an activated glycine and either from homocysteine ("reverse transsulfurylation route") or from hydrogen sulfide ("direct sulfurylation route"); the activated serine is generally O-acetylserine (via CysK or CysM in E. coli), but in Aeropyrum pernix and some other archaea O-phosphoserine is used. CysK and CysM are homologues, but belong to the PLP fold type III clade.
== Inhibitors == Proteinase K has two disulfide bonds, but it exhibits higher proteolytic activity in the presence of reducing agents (e.g. 5 mM DTT), suggesting that the presumed reduction of its own disulfide bonds does not lead to its irreversible inactivation. Proteinase K is inhibited by serine protease inhibitors such as phenylmethylsulfonyl fluoride (PMSF), diisopropylfluorophosphate (DFP), or 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF). Proteinase K activity is unaffected by the sulfhydryl modifying reagents: para-chloromercuribenzoic acid (PCMB), N-alpha-tosyl-L-lysyl-chloromethyl-ketone (TLCK), or N-alpha-Tosyl-l-phenylalanine Chloromethyl Ketone (TPCK), although presumably if these reagents were included alongside disulfide reducing reagents which exposed the typically-unavailable Proteinase K thiols, it may then become inhibited.
Sources: en.wikipedia.org
On February 19, 2019, Sanders announced that he would seek the Democratic Party's 2020 nomination for president. He had declined the Vermont Democratic Party nomination for U.S. Senate in 2006, 2012, and 2018, which caused an unsuccessful legal challenge to his candidacy for the Democratic presidential nomination in 2016. Along with his 2019 campaign announcement, he said he would abide by a new Democratic Party rule for presidential candidates and that he would affirm his membership in that party. On March 5, 2019, he signed a formal statement, known as a "loyalty pledge", that he is a member of the Democratic Party and will serve as a Democrat if elected. News reports noted that the day before, he had signed paperwork to run as an independent for reelection to his Senate seat in 2024.
== Applications == Proximity labeling methods have been used to study the proteomes of biological structures that are otherwise difficult to isolate purely and completely, such as cilia, mitochondria, postsynaptic clefts, p-bodies, stress granules, and lipid droplets. Fusion of APEX2 with G-protein coupled receptors (GPCRs) allows for both tracking GPCR signaling at a 20-second temporal resolution and also identification of unknown GPCR-linked proteins. Proximity labeling has also been used for transcriptomics and interactomics. In 2019, Alice Ting and the Ting lab have used APEX to identify RNA localized to specific cellular compartments. In 2019, BioID has been tethered to the beta-actin mRNA transcript to study its localization dynamics. Proximity labeling has also been used to find interaction partners of heterodimeric protein phosphatases, of the miRISC (microRNA-induced silencing complex) protein Ago2, and of ribonucleoproteins.
=== Drugs === Drugs can have various types of impact on the male body, side effects of medications may affect male fertility, spermatogenesis, and sexual function. Drugs can affect sperm parameters by inhibiting normal exocrine functions of the testes which can lead to a decrease in production of sperm, or by creating hormone imbalances. For an example, anti-androgenic drugs like spironolactone, cimetidine, and ketoconazole can disrupt androgens in the glands and seminal tract to cause a decrease in production of semen volume. Furthermore, common drugs (e.g. tamsulosin) used to treat hypertension and benign prostatic hyperplasia (increased size of prostate) are attracted to dopamine and serotonin receptors in the brain to cause a decrease in sperm volume through a mechanism that remains unknown. Certain medications in the following classes of drugs may affect spermatogenesis or sperm parameters*:
=== Sales and usage === Sales of bicalutamide (as Casodex) worldwide peaked at US$1.3 billion in 2007, and it has been described as a "billion-dollar-a-year" drug prior to losing its patent protection starting in 2007. In 2014, despite the introduction of abiraterone acetate in 2011 and enzalutamide in 2012, bicalutamide was still the most commonly prescribed drug in the treatment of metastatic castration-resistant prostate cancer (mCRPC). Moreover, in spite of being off-patent, bicalutamide was said to still generate a few hundred million dollars in sales per year for AstraZeneca. Total worldwide sales of brand name Casodex were approximately US$13.4 billion as of the end of 2018.
Sources: en.wikipedia.org
NAD+ and NADH can interconvert quickly after a sample is collected, which can alter the measured ratio. Rapid quenching and cold handling limit enzymatic and chemical changes.
Purity is often checked by HPLC with UV detection, sometimes paired with mass spectrometry for identity. An assay against a standard can quantify the active cofactor content.
Solid NAD+ is usually kept dry, cold, and protected from light. Aqueous working solutions are best prepared fresh because degradation depends on pH, temperature, and time.
The plus sign indicates the oxidized form of nicotinamide adenine dinucleotide, which can accept electrons. When it accepts electrons, it becomes NADH. The two forms together support redox reactions in cells.