Everything below concerns NADH. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-12-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide composed of two nucleotides joined by phosphate groups. One nucleotide contains adenine; the other contains nicotinamide. The molecule exists in oxidized (NAD+) and reduced (NADH) forms, and the reversible hydride transfer between them underlies many metabolic oxidation-reduction reactions. In cells, NAD+ serves as an electron acceptor in pathways such as glycolysis, the citric acid cycle, and oxidative phosphorylation. Its concentration and redox ratio vary by compartment, tissue, and metabolic state.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C21H27N7O14P2 | Oxidized form; NADH adds a hydride equivalent. |
| Molar mass | 663.43 g/mol | Free acid form; salts have different values. |
| CAS Registry Number | 53-84-9 | Common identifier for beta-NAD. |
| Appearance | White to off-white powder | Hygroscopic; may absorb moisture from air. |
| Solubility | Freely soluble in water | Poorly soluble in most organic solvents. |
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.
The stability of NAD+ depends on pH, temperature, light exposure, and the presence of degradative enzymes. Aqueous solutions are generally more stable under mildly acidic to neutral conditions and degrade faster under alkaline conditions or prolonged heat. The solid is hygroscopic and should be stored desiccated, often frozen, and protected from repeated freeze-thaw cycles. In laboratory handling, aliquots reduce repeated temperature changes, and chelating agents may limit metal-catalyzed hydrolysis in some buffers. These practices matter because even small amounts of NADH or hydrolysis products can interfere with quantitative assays.
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.
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.
Measuring NAD+ in biological samples requires rapid processing because the compound can degrade or interconvert after collection. Common approaches include enzymatic cycling assays, high-performance liquid chromatography, and mass spectrometry. Each method has different sensitivity, specificity, and susceptibility to interference from related nucleotides. Sample type matters: cultured cells, animal tissues, and human blood present distinct challenges. Reported values can vary widely across laboratories because of differences in extraction, normalization, and analytical platform. Standardization remains an open issue in the field.
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.
The Bushmaster project started as an offshoot of the US Army's MICV-65 program that was attempting to introduce a new infantry fighting vehicle to replace their existing M113 armored personnel carriers. Part of this program called for a new scout vehicle to replace the M114, a parallel development taking place under the XM800 Armored Reconnaissance Scout Vehicle. Both the XM800 and the cavalry version of the XM701 MICV vehicles were armed with the M139, a US-built version of the Hispano-Suiza HS.820 20 mm autocannon. During the testing phase, the Army eventually rejected the XM701 and started work on a newer design known as the XM723. Soon after the XM800 was also rejected. This led to the combination of the two programs, moving the scout role to the cavalry version of the XM723. At the same time, the M139 proved to be disappointing and a contract for a new weapon to replace it started as a competitive development in 1972 simultaneously at Ford's Aeronutronic Division with the PFB-25 (self-powered weapon) and the Hughes Helicopters' Ordnance Division (externally-powered,) under the Summa Corporation as the Vehicle Rapid-Fire Weapons System-Successor, or VRFWS-S. This was essentially a power-driven gun firing similar 20 mm ammunition to the HS.820, the power-driven mechanism was to ensure operation even in the case of a misfire. Progress on the VRFWS-S was slow, and eventually resulted in a switch to a much more powerful, 25 mm, round.
Historically an agrarian economy, Colombia urbanized rapidly in the 20th century, by the end of which just 15.8% of the workforce were employed in agriculture, generating just 6.6% of GDP; 20% of the workforce were employed in industry and 65% in services, responsible for 33% and 60% of GDP respectively. The country's economic production is dominated by its strong domestic demand. Consumption expenditure by households is the largest component of GDP. Colombia's market economy grew steadily in the latter part of the 20th century, with gross domestic product (GDP) increasing at an average rate of over 4% per year between 1970 and 1998. The country suffered a recession in 1999 (the first full year of negative growth since the Great Depression), and the recovery was long and painful. However, growth reaching 7% in 2007, one of the highest in Latin America. According to International Monetary Fund estimates, in 2023, Colombia's GDP (PPP) was US$1 trillion, 32nd in the world and third in South America, after Brazil and Argentina. Total government expenditures account for 28% of the domestic economy. External debt equals 40% of gross domestic product. A strong fiscal climate was reaffirmed by a boost in bond ratings. Annual inflation closed 2017 at 4.09% YoY (vs. 5.75% YoY in 2016). The average national unemployment rate in 2017 was 9.4%, although the informality is the biggest problem facing the labour market (the income of formal workers climbed 24.8% in 5 years while labor incomes of informal workers rose only 9%).
=== Lycopene === Lycopene is a key intermediate in the biosynthesis of beta-carotene and xanthophylls. Lycopene may be the most powerful carotenoid quencher of singlet oxygen. Due to its strong color and non-toxicity, lycopene is a useful food coloring (registered as E160d) and is approved for usage in the US, Australia and New Zealand (registered as 160d) and the EU.
Sources: en.wikipedia.org
Experimental research and computer modeling indicate that the surfaces of mineral particles inside hydrothermal vents have similar catalytic properties to enzymes and are able to create simple organic molecules, such as methanol (CH3OH) and formic acid (HCO2H), out of the dissolved CO2 in the water. Additionally, the discovery of supercritical CO2 at some sites has been used to further support the theory of hydrothermal origin of life given that it can increase organic reaction rates. Its high solvation power and diffusion rate allow it to promote amino and formic acid synthesis, as well as the synthesis of other organic compounds, polymers, and the four amino acids: alanine, arginine, aspartic acid, and glycine. In situ experiments have revealed the convergence of high N2 content and supercritical CO2 at some sites, as well as evidence for complex organic material (amino acids) within supercritical CO2 bubbles. Proponents of this theory for the origin of life also propose the presence of supercritical CO2 as a solution to the "water paradox" that pervades theories on the origin of life in aquatic settings. This paradox encompasses the fact that water is both required for life and will, in abundance, hydrolyze organic molecules and prevent dehydration synthesis reactions necessary to chemical and biological evolution. Supercritical CO2, being hydrophobic, acts as a solvent that facilitates an environment conducive to dehydration synthesis.
== External links == "VIP and PACAP Receptors". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2016-03-03. Retrieved 2007-10-25. Receptors,+Vasoactive+Intestinal+Peptide at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Mahathir's administration committed to retaining good relations with China, but promised to review all Belt and Road Initiative projects in Malaysia that were initiated by the previous government. He characterised these as "unequal treaties". His government suspended work on the East Coast Rail Link, which recommenced after terms had been renegotiated. Mahathir cancelled approximately $2.8 billion worth of deals with China Petroleum Pipeline Bureau altogether, citing high repayment costs. On 13 February 2020, Mahathir spoke with Chinese president Xi Jinping to express solidarity and discuss cooperation in response to the COVID-19 outbreak. Prior to this, Mahathir had expressed his hopes that 2020, the 'Year of Culture and Tourism' between Malaysia and China, would further strengthen the ties and friendship between the two nations.
Sources: en.wikipedia.org
There is high interindividual variability in the levels of estradiol achieved with oral estradiol, which is likely related to the high first-pass effect. This variation has been reported to be in the range of 28 to 127%, or about 4.6-fold maximal difference in levels between individuals, in terms of mean area-under-the-curve levels of estradiol. In postmenopausal women, a dosage of 1 mg/day oral micronized estradiol has been found to produce circulating concentrations of 30 to 50 pg/mL estradiol and 150 to 300 pg/mL estrone, while a dosage of 2 mg/day has been found to result in circulating levels of 50 to 180 pg/mL estradiol and 300 to 850 pg/mL estrone. A study of oral micronized estradiol in transgender women found that mean estradiol levels across a dosage range of 1 to 8 mg/day were about 50 pg/mL at 1 mg/day, 100 pg/mL at 4 mg/day, and 150 pg/mL at 8 mg/day, with a wide degree of variation. In another study, mean estradiol levels at steady state with 4 mg/day and 6 mg/day oral micronized estradiol were approximately 180 pg/mL and 265 pg/mL, respectively. A study that used high to very high-dose oral micronized estradiol in postmenopausal women found that steady-state estradiol levels with 6 mg/day were about 300 pg/mL and with 30 mg/day were about 2,400 pg/mL. Estradiol valerate is rapidly hydrolyzed into estradiol in the intestines. For this reason, oral estradiol and oral estradiol valerate have very similar pharmacokinetics.
The androgen backdoor pathways are vital for creating androgens from 21-carbon (C21) steroids, known as pregnanes. A 21-carbon steroid is a steroid molecule with 21 carbon atoms, hence, their chemical formula contains C21. For example, the chemical formula of progesterone is C21H30O2. For this reason, 21-carbon steroids are denoted as C21-steroids, 19-carbon steroids are denoted as C19 steroids, and so on. The androgen backdoor pathways occur without the involvement of testosterone (T) and/or androstenedione (A4), which are part of the conventional, canonical (classic) androgenic pathway. In the canonical pathways of androgen biosynthesis, DHT is synthesized from T via 5α-reduction, so that 5α-reduction of T, a C19 steroid, is the last step of the pathway (see Dihydrotestosterone § Biosynthesis). In the backdoor pathways, to the contrary, 5α-reduction of C21 steroids is the first step. The 5α-reduction is a chemical reaction where a functional group attached to the carbon in position 5α of the steroid nucleus is reduced, and a double bond between carbon atoms numbered 4 and 5 in the steroid molecule is replaced to the single bond in a chemical reaction catalyzed by the SRD5A1 enzyme. The androgen backdoor pathways can be also activated in pathologic conditions (diseases), such as congenital adrenal hyperplasia (CAH), leading to hyperandrogenism.
Some or all of these measurements are also carried out (usually about twice a year for routine cases) on individuals taking certain medications, such as anticonvulsants, to ensure that these medications are not adversely impacting the person's liver.
== Dosage comparison == For constant pain, the relieving effect of extended-release morphine given once (for Kadian) or twice (for MS Contin) every 24 hours is roughly the same as multiple administrations of immediate release (or "regular") morphine. Morphine sulfate pentahydrate (trade names including Dolcontin) has a higher molecular mass than morphine base, and therefore 10 mg morphine sulfate pentahydrate contains approximatively 7.5 mg of morphine free base. Extended-release morphine can be administered together with "rescue doses" of immediate-release morphine pro re nata in case of breakthrough pain, each generally consisting of 5% to 15% of the 24-hour extended-release dosage.
Sources: en.wikipedia.org
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.
No. NAD+ is oxidized and accepts electrons, while NADH is reduced and carries them. Together they form a redox pair central to energy metabolism.
NAD+ itself is not a common dietary component in significant amounts. Precursors such as nicotinamide, nicotinic acid, and nicotinamide riboside can be converted through biosynthetic pathways. Direct absorption of intact NAD+ is limited.
NAD+ is a coenzyme found in all living cells. It carries electrons in metabolic reactions and also serves as a substrate for enzymes involved in signaling and DNA repair. Its oxidized and reduced forms are central to energy metabolism.