NADH raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-01-20 and is reviewed periodically as new material appears.
Quantification of NAD+ in biological samples typically uses liquid chromatography coupled to mass spectrometry. Enzymatic cycling assays offer higher throughput and rely on NAD+ dependent dehydrogenases to amplify signal. Both approaches require careful sample quenching because NAD+ can be rapidly consumed or converted after collection. Acidic extraction is common for NAD+, while alkaline conditions favor NADH in some protocols. Isotopically labeled internal standards help correct for losses during extraction and ionization.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Forms acidic solution; salt form may alter solubility |
| Typical storage temperature | -20 °C or lower | Desiccated and protected from light |
| Common analytical method | LC-MS | Used for biological quantification |
| UV absorbance maximum | 260 nm | Aqueous solution; pH dependent |
| Common synonym | Diphosphopyridine nucleotide | Older name abbreviated DPN |
NAD+ is relatively unstable in aqueous solution, especially at neutral or alkaline pH and at elevated temperatures. It is typically stored dry, protected from light and moisture, and kept cold or frozen for long-term use. Solutions are often prepared fresh or buffered to mildly acidic pH to slow hydrolysis. Repeated freeze-thaw cycles can reduce integrity. Laboratories may verify concentration using ultraviolet absorbance at 259 nm or by enzymatic assay. These handling practices are general laboratory conventions rather than universal rules.
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.
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.
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.
In glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation, NAD+ is reduced to NADH at specific dehydrogenase steps. NADH then delivers electrons to the mitochondrial electron transport chain, mainly at complex I, supporting oxidative phosphorylation and ATP production. The balance between NAD+ and NADH, often expressed as a ratio, influences metabolic flux and redox homeostasis in different cellular compartments. Cytosolic and mitochondrial pools are connected but not identical, and their ratios can differ substantially because of compartment-specific enzymes and transport systems.
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.
Beta cells (β-cells) are specialized endocrine cells located within the pancreatic islets of Langerhans responsible for the production and release of insulin and amylin. Constituting ~50–70% of cells in human islets, beta cells play a vital role in maintaining blood glucose levels. Problems with beta cells can lead to disorders such as diabetes.
The pharyngeal jaws of teleosts, a second set of jaws contained within the throat, are composed of five branchial arches, loops of bone which support the gills. The first three arches include a single basibranchial surrounded by two hypobranchials, ceratobranchials, epibranchials and pharyngobranchials. The median basibranchial is covered by a toothplate. The fourth arch is composed of pairs of ceratobranchials and epibranchials, and sometimes additionally, some pharyngobranchials and a basibranchial. The base of the lower pharyngeal jaws is formed by the fifth ceratobranchials while the second, third and fourth pharyngobranchials create the base of the upper. In the more basal teleosts the pharyngeal jaws consist of well-separated thin parts that attach to the neurocranium, pectoral girdle, and hyoid bar. Their function is limited to merely transporting food, and they rely mostly on lower pharyngeal jaw activity. In more derived teleosts the jaws are more powerful, with left and right ceratobranchials fusing to become one lower jaw; the pharyngobranchials fuse to create a large upper jaw that articulates with the neurocranium. They have also developed a muscle that allows the pharyngeal jaws to have a role in grinding food in addition to transporting it. The caudal fin is homocercal, meaning the upper and lower lobes are about equal in size.
== Pathophysiology == Ketones are primarily produced from free fatty acids in the mitochondria of liver cells. The production of ketones is strongly regulated by insulin and an absolute or relative lack of insulin underlies the pathophysiology of ketoacidosis. Insulin is a potent inhibitor of fatty acid release, so insulin deficiency can cause an uncontrolled release of fatty acids from adipose tissue. Insulin deficiency can also enhance ketone production and inhibit peripheral use of ketones. This can occur during states of complete insulin deficiency (such as untreated diabetes) or relative insulin deficiency in states of elevated glucagon and counter-regulatory hormones (such as starvation, heavy chronic alcohol use or illness). Acetoacetic acid and β-hydroxybutyrate are the most abundant circulating ketone bodies. Ketone bodies are acidic; however, at physiologic concentrations, the body's acid/base buffering system prevents them from changing blood pH.
Sam Lonergan (born 26 March 1987) is a former professional Australian rules footballer who played for the Essendon Football Club and Richmond Football Club in the Australian Football League (AFL). He was drafted from the Launceston Football Club, via the Tassie Mariners U18s and the Tasmanian Devils, with selection 50 in the 2005 Draft. Lonergan captained the Allies (a composite team drawn from Tasmania, New South Wales, Queensland, the Australian Capital Territory and the Northern Territory), against Victoria during Grand Final week. In that game, he kicked five goals and was the leading possession winner on the ground. He also became the first player in the history of the Tassie Mariners U18s to win successive best and fairest awards. He also played eight games in 2005 for the Tasmanian Devils Football Club in the VFL competition. Lonergan was chosen as Tasmania's most valuable player at the under-18 championships in 2005, and won the Tassie Mariners U18 Best & Fairest award that same year. He was also chosen in the under-18 All-Australian side. After a 2012 season where he played 14 games and broke the shoulder blade of Andrew Carrazzo; he was delisted by the Essendon Football Club on 30 October 2012. Lonergan was picked up by Richmond in the 2012 Rookie draft, played two games for the club in 2013 and retired at the end of that year. Lonergan also supported Richmond while growing up.
The DSQ is a questionnaire designed to measure difficulty swallowing associated with eosinophilic esophagitis, with total scores ranging from 0 to 84; higher DSQ scores indicate worse symptoms. The efficacy and safety of dupilumab to treat prurigo nodularis among adults were evaluated in two clinical trials, EFC16459 (PRIME) and EFC16460 (PRIME2). Each trial evaluated 300 mg of dupilumab administered every 2 weeks following an initial dose of 600 mg. The treatment lasted for 24 weeks. Effectiveness was mainly assessed by the proportion of subjects whose itchy skin (pruritus) improved by more than four points on the Worst Itch Numeric Rating Scale, the proportion of subjects who achieved score of 0 or 1 on Investigator's Global Assessment PN-stage scale (the equivalent of 0-5 nodules), and the proportion of subjects who achieved a response on both scales at week 24. In June 2026, Alteogen disclosed that Sanofi had been utilizing its ALT-B4 recombinant human hyaluronidase platform since 2019 to develop a high-dose subcutaneous formulation of dupilumab.
Sources: en.wikipedia.org
=== Malay === Malay, just like Indonesian, is an agglutinative language (at least in the formal language) and it belongs to the Austronesian language family. The longest word in Malay is mempertanggungjawabkan, which is 22 letters long, meaning "to give responsibility to" in English.
In Britain, a number of different filmmakers came together under John Grierson. They became known as the Documentary Film Movement. Grierson, Alberto Cavalcanti, Harry Watt, Basil Wright, and Humphrey Jennings amongst others succeeded in blending propaganda, information, and education with a more poetic aesthetic approach to documentary. Examples of their work include Drifters (John Grierson), Song of Ceylon (Basil Wright), Fires Were Started, and A Diary for Timothy (Humphrey Jennings). Their work involved poets such as W. H. Auden, composers such as Benjamin Britten, and writers such as J. B. Priestley. Among the best-known films of the movement are Night Mail and Coal Face. Calling Mr. Smith (1943) is an anti-Nazi color film created by Stefan Themerson which is both a documentary and an avant-garde film against war.
In December 2010, Chipotle hired chef Nate Appleman to develop new cuisine. Appleman has won Rising Star Chef from the James Beard Foundation, was named "Best New Chef" by the Food & Wine magazine, and competed on The Next Iron Chef. In 2010, U.S. Immigration and Customs Enforcement (ICE) audited Chipotle's Minneapolis restaurants, and found that some employees had been hired using fraudulent documents. In December, Chipotle fired 450 employees from its Minneapolis restaurants as a result of the audit, resulting in protests by local groups. In February 2011, ICE expanded the audit to include 60 restaurants in Virginia and Washington, D.C. which resulted in 40 workers being fired. In April 2011, the criminal division of the attorney general's office in Washington, D.C., joined the case, and ICE agents began interviewing employees at 20 to 25 restaurants in other locations, such as Los Angeles and Atlanta. In response to the government investigations, Chipotle hired former director of ICE Julie Myers Wood and high-profile attorneys Robert Luskin and Gregory B. Craig. In April 2014, Chipotle announced an increase in menu prices for the first time in nearly three years, due to increasing costs for steak, avocados, and cheese. The price increase was expected to be rolled out from the end of the second quarter of 2014 through the end of the third quarter. In late 2015, Chipotle expanded its mobile strategy through delivery partnerships with tech startups like Tapingo, a delivery service that targets college campuses.
== Chemistry == 2C-B, also known as 4-bromo-2,5-dimethoxyphenethylamine, is a substituted phenethylamine of the 2C family, also known as the 4-substituted 2,5-dimethoxyphenethylamines. It is a synthetic analogue of the naturally occurring phenethylamine psychedelic mescaline found in peyote and certain other cacti.
Sources: en.wikipedia.org
Caffeine is a stimulant compound belonging to the xanthine class of chemicals naturally found in coffee, tea, and (to a lesser degree) cocoa or chocolate. Caffeine is included in many soft drinks, as well as a larger amount in energy drinks. It is the world's most widely used psychoactive drug and by far the most common stimulant. In North America, 90% of adults consume caffeine daily. A few jurisdictions restrict the sale and use of caffeine. In the United States, the Food and Drug Administration has banned the sale of pure and highly concentrated caffeine products for personal consumption, due to the risk of overdose and death. The Australian Government has announced a ban on the sale of pure and highly concentrated caffeine food products for personal consumption, following the death of a young man from acute caffeine toxicity. In Canada, Health Canada has proposed to limit the amount of caffeine in energy drinks to 180 mg per serving, and to require warning labels and other safety measures on these products. Caffeine is also included in some medications, usually for the purpose of enhancing the effect of the primary ingredient, or reducing one of its side effects (especially drowsiness). Tablets containing standardized doses of caffeine are also widely available. Caffeine's mechanism of action differs from many stimulants, as it produces stimulant effects by inhibiting adenosine receptors. Adenosine receptors are thought to be a large driver of drowsiness and sleep, and their action increases with extended wakefulness.
Upon activation, bAREs ADP-ribosylate any number of eukaryotic proteins; such mechanism is crucial to the instigation of the diseased states associated with ADP-ribosylation. GTP-binding proteins, in particular, are well-established in bAREs pathophysiology. For examples, cholera and heat-labile enterotoxin target the α-subunit of Gs of heterotrimeric GTP-binding proteins. As the α-subunit is ADP-ribosylated, it is permanently in an "active", GTP-bound state; subsequent activation of intracellular cyclic AMP stimulates the release of fluid and ions from intestinal epithelial cells. Furthermore, C. Botulinum C3 ADP-ribosylates GTP-binding proteins Rho and Ras, and Pertussis toxin ADP-ribosylates Gi, Go, and Gt. Diphtheria toxin ADP-ribosylates ribosomal elongation factor EF-2, which attenuates protein synthesis. There are a variety of bacteria which employ bAREs in infection: CARDS toxin of Mycoplasma pneumoniae, cholera toxin of Vibrio cholerae; heat-labile enterotoxin of E. coli; exotoxin A of Pseudomonas aeruginosa; pertussis toxin of B. pertussis; C3 toxin of C. botulinum; and diphtheria toxin of Corynebacterium diphtheriae.
After Friedrich Raschig developed a method to synthesize hydrazine, Hans Meyer and his doctoral student at the German University in Prague Josef Mally researched hydrazides of pyridinecarboxylic acids. By reacting ethyl isonicotinate with hydrazine hydrate, they obtained a compound which, after recrystallization, possessed a melting point of 163°C. Despite its publication in 1912, the compound's pharmaceutical properties were not investigated for decades. In the 1940s, French physicians discovered that nicotinamide had some activity against tubercle bacilli in vitro and in infected guinea pigs. At the same time, German chemists led by G. Domagk investigating sulfo drugs at Bayer developed thioacetazone. After their findings were made public, in 1950 A. Girard modified it to the less toxic thiosemicarbazone of nicotinaldehyde while H. H. Fox developed similar isonicotinaldehyde thiosemicarbazone.
Sources: en.wikipedia.org
Aqueous NAD+ solutions are best kept frozen in aliquots and protected from light. Repeated freezing and thawing is avoided because it can accelerate breakdown. Dry powder stored desiccated at -20 °C or lower typically remains stable for longer periods.
Liquid chromatography-mass spectrometry provides sensitive and specific quantification in cells and tissues. Enzymatic cycling assays are also widely used for plate-based measurement. Both methods need rapid sample processing to prevent post-collection changes.
Purity refers to the proportion of the intended dinucleotide relative to related nucleotides, salts, and water. A high-purity grade supports reproducible enzymatic assays. Researchers often check purity by chromatographic and spectroscopic methods before use.
It indicates a formal positive charge on the nicotinamide ring. The molecule is not simply a protonated acid, and the charge is part of its redox chemistry.