If you have been reading about nicotinamide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-02-23. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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 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.
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.
Solid NAD+ is usually supplied as a white to off-white powder or lyophilized preparation. It is hygroscopic and should be kept desiccated at low temperature, commonly -20 °C or below for long-term storage. Aqueous solutions are less stable than dry material and are often prepared fresh or stored frozen in aliquots. Light exposure and repeated freeze-thaw cycles can promote degradation, so amber containers and single-use aliquots are preferred. Buffered solutions near neutral pH are generally less stable than acidic or frozen preparations.
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.
=== Drainage === Aqueous humor is continually produced by the ciliary processes and this rate of production must be balanced by an equal rate of aqueous humor drainage. Small variations in the production or outflow of aqueous humor will have a large influence on the intraocular pressure. The drainage route for aqueous humor flow is first through the posterior chamber, then the narrow space between the posterior iris and the anterior lens (contributes to small resistance), through the pupil to enter the anterior chamber. From there, the aqueous humor exits the eye through the trabecular meshwork into Schlemm's canal (a channel at the limbus, i.e., the joining point of the cornea and sclera, which encircles the cornea). It flows through 25–30 collector canals into the episcleral veins. The greatest resistance to aqueous flow is provided by the trabecular meshwork (esp. the juxtacanalicular part), and this is where most of the aqueous outflow occurs. The internal wall of the canal is very delicate and allows the fluid to filter due to the high pressure of the fluid within the eye. The secondary route is the uveoscleral drainage, and is independent of the intraocular pressure, the aqueous flows through here, but to a lesser extent than through the trabecular meshwork (approx. 10% of the total drainage whereas by trabecular meshwork 90% of the total drainage). The fluid is normally 15 mmHg (0.6 inHg) above atmospheric pressure, so when a syringe is injected the fluid flows easily.
Ballistics is "the science of the motion of projectiles in flight". In forensic science, analysts examine the patterns left on bullets and cartridge casings after being ejected from a weapon. When fired, a bullet is left with indentations and markings that are unique to the barrel and firing pin of the firearm that ejected the bullet. This examination can help scientists identify possible makes and models of weapons connected to a crime. Henry Goddard at Scotland Yard pioneered the use of bullet comparison in 1835. He noticed a flaw in the bullet that killed the victim and was able to trace this back to the mold that was used in the manufacturing process.
=== Pharmacodynamics === Chloral hydrate is metabolized in vivo to trichloroethanol, which is responsible for secondary physiological and psychological effects. The metabolite of chloral hydrate exerts its pharmacological properties via enhancing the GABA receptor complex and therefore is similar in action to benzodiazepines, nonbenzodiazepines and barbiturates. It can be moderately addictive, as chronic use is known to cause dependency and withdrawal symptoms. The chemical can potentiate various anticoagulants and is weakly mutagenic in vitro and in vivo. Chloral hydrate inhibits liver alcohol dehydrogenase in vitro. This could be an explanation of the synergeric effect seen with alcohol. Chloral hydrate is structurally and somewhat pharmacodynamically similar to ethchlorvynol, a pharmaceutical developed during the 1950s that was marketed as both a sedative and a hypnotic under the trade name Placidyl. In 1999, Abbott, the sole manufacturer of the drug in the United States at the time, decided to discontinue the product. After Abbott ceased production, the drug remained available for about a year. Despite the fact that it could have been manufactured generically, no other company in the United States chose to do so.
study of complex formation in supramolecular systems – organized ensembles surfactants and macrocyclic ligands; study of coordination compounds of iron (III) and manganese (II) for magnetic resonance imaging; obtaining new types of hybrid organic-inorganic functional materials based on nanoscale hyperbranched structures. Results of these studies are of basic value in the area of coordination chemistry, bioinorganic chemistry, chemistry of nanomaterials, pharmaceutical chemistry. Proposed model and physio-chemical basis of self-assembly of nanoscale of hyperbranched polymers, set new approaches to understanding the mechanisms of gene transfection and targeted drug delivery.
Sources: en.wikipedia.org
== Prenatal environment == The development of autism is associated with several prenatal risk factors, including advanced age in either parent, diabetes, bleeding, and maternal use of antibiotics and psychiatric drugs during pregnancy. Autism has been linked to birth defect agents acting during the first eight weeks from conception, though these cases are rare. If the mother of the child is dealing with autoimmune conditions or disorders while pregnant, it may have an effect on the child's development of autism. All of these factors can cause inflammation or impair immune signaling in one way or another.
At the end of its 2013 fiscal year, Burger King was the second largest chain of hamburger fast food restaurants in terms of global locations, behind industry bellwether McDonald's, which had 32,400 locations. At the end of 2014, Burger King ranked fourth among US food chains in terms of US sales, behind McDonald's, Starbucks, and Subway. Burger King now has over 12,000 stores worldwide. In January 2024, Restaurant Brands International, the owner of the brand, announced it would purchase the largest franchisee of the chain, Carrols Restaurant Group, for around $1 billion. At the time of the announcement, Carrols had 1,022 Burger King locations (along with 60 Popeyes locations). The goal was to remodel 600 of the restaurants, then sell them back to franchisees over five to seven years. The move represented a departure from the existing model of largely franchising locations.
Fibromyalgia can be viewed as a condition defined by nociplastic pain. Nociplastic pain is caused by altered function of pain-related sensory pathways in the periphery and the central nervous system, resulting in hypersensitivity. As of 2023, the underlying processes of nociplastic pain remain poorly understood. Nociplastic pain may be caused by either (1) increased processing of pain stimuli or (2) decreased suppression of pain stimuli at several levels in the nervous system, or both. Nociplastic pain has been referred to as "Nociplastic pain syndrome" because it is coupled with other symptoms including fatigue, sleep disturbance, cognitive disturbance, hypersensitivity to environmental stimuli, anxiety, and depression. Nociplastic pain states can be triggered by a variety of stressors such as trauma, infections, and chronic stressors. A 2024 review reported that symptoms such as fatigue, sleep, memory, and mood problems, and sensitivity to non-painful sensory stimuli were also CNS-driven symptoms that were inherent to nociplastic pain. In 2023, the "Fibromyalgia: Imbalance of Threat and Soothing Systems" (FITSS) model was suggested as a working hypothesis. According to the FITSS model, the salience network (also known as the midcingulo-insular network) may remain continuously hyperactive due to an imbalance in emotional self-regulation, which is reflected by an overactive "threat" system and an underactive "soothing" system. This hyperactivation, along with other mechanisms, may contribute to fibromyalgia.
=== Neuromuscular adaptations === Strength training is not only associated with an increase in muscle mass, but also an improvement in the nervous system's ability to recruit muscle fibers and activate them at a faster rate. Neural adaptations can occur in the motor cortex, the spinal cord, and/or neuromuscular junctions. The initial significant improvements in strength amongst new lifters are a result of increased neural drive, motor unit synchronization, motor unit excitability, rate of force development, muscle fiber conduction velocity, and motor unit discharge rate. Together, these improvements provide an increase in strength separate from muscle hypertrophy. Typically, the main barbell lifts – squat, bench, and deadlift – are performed with a full range of motion, which provides the greatest neuromuscular improvements compared to one-third or two-thirds range of motion. However, there are reasons to perform these lifts with less range of motion, particularly in the powerlifting community. By limiting range of motion, lifters can target a specific joint angle in order to improve their sticking points by training their neural drive. Neuromuscular adaptations are critical for the development of strength, but are especially important in the aging adult population, as the decline in neuromuscular function is roughly three times as great (≈3% per year) as the loss of muscle mass (≈1% per year). By staying active and following a resistance training program, older adults can maintain their movement, stability, balance, and independence.
=== Autoimmune diseases === Problems posed by the differences in the human and rodent immune systems have been overcome using a few strategies, so as to enable researchers to study autoimmune disorders using humanized models. As a result, the use of humanized mouse models has extended to various areas of immunology and disease research. For instance, humanized mice have been utilized to study human-tropic pathogens, liver cancer models, and the comparison of mouse models to human diseases NSG mice engrafted with PBMCs and administered with myelin antigens in Freund's adjuvant, and antigen-pulsed autologous dendritic cells have been used to study multiple sclerosis. Similarly, NSG mice engrafted with hematopoietic stem cells and administered with pristane have been used for studying lupus erythematosus. Furthermore, NOG mice engrafted with PBMCs has been used to study mechanisms of allografts rejection in vivo. The development of humanized mouse models has significantly advanced the study of autoimmune disorders and various areas of immunology and disease research. These models have provided a platform for investigating human diseases, immune responses, and therapeutic interventions, bridging the gap between human and rodent immune systems and offering valuable insights into disease pathogenesis and potential therapeutic strategies.
Sources: en.wikipedia.org
Reaction between tin tetrachloride and sulfuric acid in a 1:2 molar mixture at near reflux (114 °C): SnCl4 + 2 H2SO4 → Sn(SO4)2 + 4 HCl Pyrolysis of anhydrous tin(IV) sulfate at 150 °C - 200 °C: Sn(SO4)2 → SnO2 + 2 SO3 To further reduce water contamination, Oleum and a slight excess of Tin(IV) Chloride should be used. The slight excess of SnCl4 can then be separated by carefully heating the solid Tin(IV) Sulfate under a vacuum to no more than 120 °C. The excess SO3 from the Oleum and the remaining SnCl4 will react during HCl formation and form Tin(IV) Oxide and Sulfuryl Chloride. If an excess of SO3 in the Oleum is present relative to SnCl4 , the Tin(IV) Oxide will absorb it and form more Tin(IV) Sulfate. The advantage of this method over the sodium bisulfate one is that it can produce the pure trimer of SO3 (since no water is present) while still using safe temperatures for normal borosilicate laboratory glassware. Other dry sulfate salt pyrolysis reactions require higher temperatures which increases the risk of shattering. A disadvantage is that it generates significant quantities of hydrogen chloride gas which needs to be captured as well. SO3 may also be prepared by dehydrating sulfuric acid with phosphorus pentoxide.
An analysis of events in the US FDA Adverse Event Reporting System suggests an association between several GLP-1 agonists (including semaglutide) and cutaneous reactions, such as dermal hypersensitivity reactions, eosinophilic panniculitis, bullous pemphigoid, and morbilliform drug eruptions. In August 2026, a post hoc analysis of the SELECT phase 3 trial involving adults aged 65 and older without diabetes revealed that 104 weeks of semaglutide treatment slowed the progression of a validated 25-protein blood signature (Dementia SomaSignal Test) predicting long-term all-cause dementia risk. Participants receiving semaglutide experienced a 26% lower predicted 5-year dementia risk compared to placebo, with the majority of the protective association persisting independent of weight loss alone.
In organic chemistry, a condensation reaction is a type of chemical reaction in which two molecules are combined to form a single molecule, usually with the loss of a small molecule such as water. If water is lost, the reaction is also known as a dehydration synthesis. However other molecules can also be lost, such as ammonia, ethanol, acetic acid and hydrogen sulfide. The addition of the two molecules typically proceeds in a step-wise fashion to the addition product, usually in equilibrium, and with loss of a water molecule (hence the name condensation). The reaction may otherwise involve the functional groups of the molecule, and is a versatile class of reactions that can occur in acidic or basic conditions or in the presence of a catalyst. This class of reactions is a vital part of life as it is essential to the formation of peptide bonds between amino acids and to the biosynthesis of fatty acids.
A 2011 review found that caffeine during pregnancy does not appear to increase the risk of congenital malformations, miscarriage or growth retardation even when consumed in moderate to high amounts. Other reviews concluded that there is some evidence that higher caffeine intake by pregnant women may be associated with a higher risk of giving birth to a low birth weight baby, and may be associated with a higher risk of pregnancy loss. A meta-analysis found a correlation between childhood obesity and maternal caffeine intake during pregnancy. A systematic review analyzed the results of observational studies, and found that women who consumed large amounts of caffeine (greater than 300 mg/day) prior to becoming pregnant may have had a higher risk of experiencing pregnancy loss.
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.
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.