Everything below concerns NADH. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-11-09. Numbers and descriptions here follow the published literature rather than marketing material.
NAD+ is a dinucleotide composed of adenine, ribose, and nicotinamide groups joined by phosphate linkages. It serves as a coenzyme in oxidoreductase reactions, cycling between oxidized NAD+ and reduced NADH. The molecule is water-soluble and occurs in all living cells. Its nicotinamide ring accepts hydride ions during catabolic reactions, linking substrate oxidation to electron transport. This redox couple supports ATP production and helps maintain cytosolic and mitochondrial redox balance in many cell types.
Beyond redox catalysis, NAD+ is a substrate for enzymes that transfer ADP-ribose or remove acetyl groups from proteins. Sirtuins and poly(ADP-ribose) polymerases consume NAD+ and release nicotinamide as a byproduct. These reactions connect cellular energy status to gene regulation, DNA repair, and stress responses. Because NAD+ is used rather than merely recycled in such signaling, its concentration reflects both biosynthesis and consumption. The balance between salvage and de novo synthesis pathways determines available pools in different tissues.
Biosynthesis of NAD+ starts from nicotinamide, nicotinic acid, or nicotinamide riboside through salvage pathways. A rate-limiting enzyme, nicotinamide phosphoribosyltransferase, converts nicotinamide to nicotinamide mononucleotide. Further coupling with ATP yields NAD+. In mammals, the liver and muscle can synthesize NAD+ from dietary precursors, but tissue levels vary widely. Researchers study these pathways to understand age-related changes, metabolic disorders, and neurodegeneration. Direct causal links between NAD+ decline and disease remain an active area of investigation.
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 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.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C21H27N7O14P2 | Applies to the free acid form of beta-NAD+ |
| Molar mass | 663.43 g/mol | Calculated from the free acid formula |
| Redox couple | NAD+/NADH | Standard reduction potential near -0.32 V at pH 7 |
| Primary role | Electron carrier | Participates in oxidoreductase reactions |
| Common synonym | Diphosphopyridine nucleotide | Historical abbreviation DPN |
Solid NAD+ is relatively stable when kept dry, cold, and protected from light. Aqueous solutions are more vulnerable to hydrolysis and can lose activity during repeated freeze-thaw cycles or prolonged storage at ambient temperature. Stability depends on pH, ionic strength, and the presence of degrading enzymes or metal ions. For many laboratory uses, aliquots are stored frozen and thawed only once. Exact degradation rates vary by matrix, so stability should be checked for each application rather than assumed.
Laboratory handling of NAD+ follows standard practices for hygroscopic fine chemicals. Personnel typically avoid inhalation and skin contact, use gloves and eye protection, and work in a ventilated area. Quality control may include ultraviolet absorbance at the nicotinamide maximum, chromatographic purity, water content, and identity confirmation by mass spectrometry. Because commercial preparations can contain counterions, residual solvents, or related nucleotides, a certificate of analysis helps verify the material. Researchers should confirm that the form supplied matches the intended assay.
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 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.
Quality control for NAD+ materials typically combines identity, purity, and water content checks. Identity may be confirmed by ultraviolet spectrum, retention time in chromatography, or mass accuracy, while purity is assessed by HPLC peak area or quantitative nuclear magnetic resonance. Residual water and solvents can affect molar calculations and enzyme assays, so Karl Fischer titration or thermogravimetric analysis may be used. Commercial materials vary in grade and counterion form, and published methods should specify the exact salt or hydrate when reporting concentrations. Regulatory status depends on intended use, with research reagents, dietary ingredients, and clinical products treated under different frameworks.
Quantification of NAD+ in biological samples usually relies on separation techniques coupled to sensitive detection. High-performance liquid chromatography with ultraviolet detection can measure the oxidized form by its absorbance near 260 nm, while mass spectrometry provides greater specificity and can distinguish NAD+ from close analogs. Enzymatic cycling assays use coupled dehydrogenase reactions to amplify signal and estimate NAD+ concentrations in cell or tissue extracts. Because NAD+ and NADH interconvert rapidly, sample preparation must quench metabolism quickly and preserve the redox state before analysis.
== History == More than 50 years ago, MSI was introduced using secondary ion mass spectrometry (SIMS) to study semiconductor surfaces by Castaing and Slodzian. However, it was the pioneering work of Richard Caprioli and colleagues in the late 1990s, demonstrating how matrix-assisted laser desorption/ionization (MALDI) could be applied to visualize large biomolecules (as proteins and lipids) in cells and tissue to reveal the function of these molecules and how function is changed by diseases like cancer, which led to the widespread use of MSI. Nowadays, different ionization techniques have been used, including SIMS, MALDI and desorption electrospray ionization (DESI), as well as other technologies. Still, MALDI is the current dominant technology with regard to clinical and biological applications of MSI.
Tomato – in culinary terms, the tomato is regarded as a vegetable, but it is botanically classified as a fruit and a berry. Banana – the fruit has been described as a "leathery berry". In cultivated varieties, the seeds are diminished nearly to non-existence. Pepo – berries with skin that is hardened: cucurbits, including gourds, squash, melons. Hesperidium – berries with a rind and a juicy interior: most citrus fruit. Cranberry, gooseberry, redcurrant, grape. The strawberry, regardless of its appearance, is classified as a dry, not a fleshy fruit. Botanically, it is not a berry; it is an aggregate-accessory fruit, the latter term meaning the fleshy part is derived not from the plant's ovaries but from the receptacle that holds the ovaries. Numerous dry achenes are attached to the outside of the fruit-flesh; they appear to be seeds but each is actually an ovary of a flower, with a seed inside. Schizocarps are dry fruits, though some appear to be fleshy. They originate from syncarpous ovaries but do not actually dehisce; rather, they split into segments with one or more seeds. They include a number of different forms from a wide range of families, including carrot, parsnip, parsley, cumin.
=== Recovery from trauma === Bemethyl has also been shown to prevent permanent hearing loss and facilitate recovery of hearing after mine-explosion trauma, when treatment is initiated immediately after injury.
Sources: en.wikipedia.org
=== Pharmacokinetics === Following a single topical application of 10 g nadifloxacin 1% cream to normal human back skin, the highest plasma concentration was determined to be 107 ng/mL with an elimination half-life of 19.4 hours. Approximately 0.09% of the administered dose was excreted in the urine over 48 hours post- dosing. The plasma concentration reached a steady state on Day 5 of repeated administration study when nadifloxacin 1% cream was applied at 5 g twice daily to normal healthy individuals for a period of 7 days. The plasma concentration reached a peak of 4.1 ng/ml at 8 hours post-final dosing with an elimination half-life of 23.2 hours. The urinary excretion rate reached 0.16% on Day 7.
The meteorite contained a mixture of left-handed and right-handed amino acids; most amino acids used by living organisms are left-handed in chirality, and most sugars used are right-handed. A team of chemists in Sweden demonstrated in 2005 that this homochirality could have been triggered or catalyzed by the action of a left-handed amino acid such as proline. Several lines of evidence indicate that the interior portions of well-preserved fragments from Murchison are pristine. A 2010 study using high resolution analytical tools including spectroscopy, identified 14,000 molecular compounds, including 70 amino acids, in a sample of the meteorite. The limited scope of the analysis by mass spectrometry provides for a potential 50,000 or more unique molecular compositions, with the team estimating the possibility of millions of distinct organic compounds in the meteorite. In November 2019, along with the Northwest Africa 801 meteorite it was the first to provide evidence of pentoses (including ribose) in space, using gas chromatography–mass spectrometry. All the straight-chain five-carbon aldoses were found but tetroses, sugar alcohols, sugar acids, and deoxyribose were not detected. In 2020, NASA announced that hexamethylenetetramine had been found in the Murchison, Murray and Tagish Lake meteorites.
Intra-articular steroid injections often help with treatment in oligoarticular JIA. Conventional synthetic DMARDs, such as methotrexate are a first-line therapy, and biologic DMARDs such as TNF-α inhibitors may be added on for refractory cases. Rheumatoid factor-negative polyarticular JIA (15-20% of all JIA cases) can be treated with synthetic conventional DMARDs (such as methotrexate), with biologic DMARDs (such as TNF inhibitors) being a second-line add-on treatment option. Rheumatoid factor-positive JIA (5% of JIA cases, and also being rare in children younger than 9-years old) is associated with a poor prognosis, and early treatment is required to prevent significant joint destruction and disability. It is very similar pathologically to adult rheumatoid arthritis. Synthetic conventional DMARDs or biologic DMARDs are standard therapy for this type of JIA. Enthesitis-related arthritis is a type of JIA characterized by enthesitis; inflammation of the area where tendons and ligaments attach to bone. NSAIDs are commonly used for symptomatic relief, with the anti-inflammatories sulfasalazine and TNF inhibitors also being used. Biologic DMARDs such as TNF-α inhibitors are used for sacroilitis (inflammation of the sacroiliac joint). IL-17 inhibitors are used for refractory disease. 40-60% of children with enthesitis-related variant of JIA have involvement of the axial skeleton, including sacroiliitis, spondyloarthritis, and ankylosing spondylitis (inflammation of the spine).
On Czapek Yeast Extract Agar medium at 25 °C, white colonies grow in a plane, attaining a velvety to deeply floccose texture, with colony sizes that are 33–35 mm in diameter. On this medium, olive conidia are produced. The reverse of the plate can be pale or slightly tinted brown. On Malt Extract Agar medium at 25 °C, growth is rare, yet rapid when occurring, forming a velvety surface. At first, colonies are yellow-green, but ultimately turn olive due to conidial production. Colony diameter can range in size from 35 mm to 70 mm. The reverse of the plate is similar to that observed for Czapek Yeast Extract Agar medium. On 25% Glycerol Nitrate Agar at 25 °C, colony growth is planar, yet develops into a thick gel, with colony size diameter ranging from 6–12 mm. The back of the plate is described as pale or olive. At 5 °C, 25% Glycerol Nitrate Agar supports germination and a colonial growth of up to 3 mm in diameter. This species fails to grow at 37 °C. On Creatine Sucrose Agar at 25 °C, colony size diameter ranges from 4 to 10 mm. Growth is restricted, and medium pH remains around 7. No change on the back of the plate is noted. Growth on media containing orange fruit pieces for seven days at room temperature results in fruit decay, accompanied by a characteristic odour. After 14 days at room temperature, the reverse is colourless to light brown.
Sources: en.wikipedia.org
Considering that a high partial pressure of oxygen is present in lungs and DMA(III) is excreted in gaseous state via the lungs, this seems to be a plausible mechanism for special vulnerability. The fact that DMA is produced by methylation in the liver, excreted via the kidneys, and later on stored in the bladder accounts for the other tumor localizations. Regarding DNA methylation, some studies suggest interaction of As with methyltransferases, which leads to an inactivation of tumor suppressor genes through hypermethylation; others state that hypomethylation might occur due to a lack of SAM, resulting in aberrant gene activation. An experiment by Zhong et al. (2001) with arsenite-exposed human lung A549, kidney UOK123, UOK109 and UOK121 cells isolated eight different DNA fragments by methylation-sensitive arbitrarily primed polymerase chain reactions. It turned out that six of the fragments were hyper- and two of them were hypomethylated. Higher levels of DNA methyltransferase mRNA and enzyme activity were found. Kitchin (2001) proposed a model of altered growth factors, which lead to cell proliferation and thus to carcinogenesis. From observations, it is known that chronic low-dose arsenic poisoning can lead to increased tolerance to its acute toxicity. MRP1-overexpressing lung tumor GLC4/Sb30 cells poorly accumulate arsenite and arsenate. This is mediated through MRP-1-dependent efflux. The efflux requires glutathione, but no arsenic-glutathione complex formation.
== Compliance and deviation == In international law, it is said that "treaty interpretation is an art, not a science" Expanding that view, Philip Allott states that "interpretation in International Law is an art and a game and a field of battle." While the drug conventions define clear limitations, and the VCLT serves as a critical interpretive tool, there is "a degree of latitude for policy choices at the national and subnational level" that has allowed for ample interpretive divergence. One study examining interpretive latitude in the conventions proposed three categories of deviation by member countries: permissible policies deviate while being generally accepted, contested policies are vigorously defended as in fact being within the guidelines, and impermissible policies are clear breaches of the conventions. In recent decades, a growing number of countries, and a majority of states in the US, have moved towards drug liberalization by variously decriminalizing cannabis and other drugs for personal consumption, and by legalizing cannabis for recreational use. This has resulted in a variety of interpretations of, and tension with, the drug treaties.
non-small cell lung cancers (30–46%) head and neck squamous cell carcinomas (30–50%) pancreatic carcinomas (25%) bladder cancer (15%) pituitary adenomas (49–54%) breast carcinoma (13%) Cyclin D1 overexpression is strongly correlated to ER+ breast cancer and deregulation of cyclin D1 is associated with hormone therapy resistance in breast cancer. Overexpression of Cyclin D1b, an isoform, is also present in breast and prostate cancers. Chromosomal translocation around the cyclin D1 gene locus is often seen in B mantle cell lymphoma. In mantle cell lymphoma, cyclin D1 is translocated to the IgH promoter leading to cyclin D1 overexpression. Chromosomal translocation of the cyclin D1 gene locus is also observed in 15–20% of multiple myelomas.
The most versatile synthesis developed by the Swiss team first involved alkylation of 2,4-dinitrochlorobenzene with 1-amino-2-diethylaminoethane to form N-(β-diethylaminoethyl)-2,4-dinitroaniline (also known as N′-(2,4-dinitrophenyl)-N,N-diethyl-ethane-1,2-diamine). The 2-nitro substituent on the 2,4-dinitroaniline compound is then selectively reduced to the corresponding primary amine by utilizing ammonium sulfide as the reducing agent. The ammonium sulfide can be formed in situ by the addition of concentrated aqueous ammonium hydroxide followed by saturation of the solution with hydrogen sulfide gas. The intermediate formed by the selective reduction of the 2-nitro substituent, 2-(β-diethylaminoethylamino)-5-nitroaniline, is then reacted with the hydrochloride salt of the imino ethyl ether of 4-ethoxyphenylacetonitrile (a.k.a. p-ethoxybenzyl cyanide). The imino ether, 2-(4-ethoxyphenyl)-acetimidic acid ethyl ester hydrochloride, is prepared by dissolving the 4-substituted benzyl cyanide in a mixture of anhydrous ethanol and chloroform and then saturating this solution with dry hydrogen chloride gas. The reaction between the 2-(β-dialkylaminoalkylamine)-5-nitroaniline and the HCl salt of the imino ethyl ether results in the formation of etonitazene. This procedure is particularly useful in the preparation of the 4-, 5-, 6-, and 7-nitrobenzimidazoles. Varying the choice of the substituted phenylacetic acid imino ether affords compounds with a diversity of substituents on the benzene ring at the 2- position.
There are many substances that are purported to have promise in augmenting human cognition by various means. These substances are called nootropics and can potentially benefit individuals with cognitive decline and many different disorders, but may also be capable of yielding results in cognitively healthy persons. Generally speaking, nootropics are said to be effective for enhancing focus, learning, memory function, mood, and in some cases, physical brain development. Some examples of these include Citicoline, Huperzine A, Phosphatidylserine, Bacopa monnieri, Acetyl-L-carnitine, Uridine monophosphate, L-theanine, Rhodiola rosea, and Pycnogenol which are all forms of dietary supplement. There are also nootropic drugs such as the common racetams, e.g. piracetam (Nootropil) and omberacetam (Noopept) along with the neuroprotective Semax, and N-Acetyl Semax. There are also nootropics related to naturally occurring substances but that are either modified in a lab or are analogs such as Vinpocetine and Sulbutiamine. Some authors have explored nootropics as relationship enhancements to help couples maintain bonds over time.
Sources: en.wikipedia.org
NAD+ is the oxidized form and NADH is the reduced form of the same coenzyme. NAD+ accepts electrons during oxidation reactions, becoming NADH, which can donate electrons in other reactions. The ratio between them helps describe a cell's redox state.
No; NAD+ and related dinucleotides occur across bacteria, archaea, plants, fungi, and animals. Its central role in electron transfer and enzyme catalysis is deeply conserved, though specific pathways for making and using it can differ among organisms.
NAD+ is a charged, water-soluble dinucleotide and generally does not diffuse freely across cell membranes. Cells rely on precursor molecules and dedicated transport or salvage pathways. This limited permeability shapes how researchers deliver or measure NAD+ in experimental systems.
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.