A practical reference on HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Commercial NMN is produced through enzymatic or chemical routes, and the resulting material can vary in purity, counterion, and residual solvent content. Buyers typically rely on certificates of analysis, but independent verification through third-party laboratories provides stronger assurance. Regulatory treatment differs by country; in the United States, NMN has been subject to shifting guidance about its status as a dietary supplement, while other markets permit sales under local rules. No universal pharmacopeial monograph exists for NMN, so specifications often come from suppliers, research protocols, or regional requirements.
Solid NMN is generally handled as a moisture-sensitive compound. Dry material stored desiccated at low temperature, protected from light, tends to remain stable for extended periods. Aqueous solutions are less stable and can undergo hydrolysis, especially at elevated temperature or alkaline pH. The anomeric form also matters: beta-NMN is the naturally occurring form, while alpha-NMN can appear as a synthetic impurity. Purity and storage conditions therefore influence both analytical results and experimental reproducibility.
Beyond its intracellular synthesis, NMN can be taken up from the extracellular environment, although the routes are still debated. Some evidence points to direct transport into cells through specific transporters, while other work suggests dephosphorylation to nicotinamide riboside followed by cellular uptake. Once inside, NMN can be converted to NAD+ by NMN adenylyltransferases; the relative contribution of these routes may differ by tissue, species, and experimental conditions. Researchers continue to investigate which mechanisms dominate in intact organisms and how they affect measured NAD+ levels. Direct measurement in tissues remains technically challenging because NMN can be rapidly metabolized during sample collection.
NMN occurs in many living systems, including bacteria, yeast, plants, and mammals. Dietary sources are present in foods such as edamame, avocado, broccoli, and various meats, but amounts vary widely and are generally lower than those used in research settings. Laboratory production often relies on enzymatic synthesis or chemical phosphorylation of nicotinamide riboside, and commercial material is typically supplied as a white to off-white powder. Because NMN is hygroscopic and sensitive to heat, moisture, and pH extremes, its handling requires care to preserve identity and purity. Aqueous preparation should be done with attention to pH and temperature to limit hydrolysis.
Nicotinamide mononucleotide, abbreviated NMN, is a naturally occurring nucleotide found in cells. Its structure consists of a nicotinamide ring linked to ribose phosphate, and the compound serves as an intermediate in the salvage pathway for nicotinamide adenine dinucleotide, or NAD+. In this pathway, nicotinamide phosphoribosyltransferase converts nicotinamide and phosphoribosyl pyrophosphate into NMN, after which NMN adenylyltransferase attaches an adenylate group to produce NAD+. Because NAD+ participates in redox reactions and signaling, NMN occupies a central position in cellular metabolism. The molecule is distinct from nicotinamide riboside, though the two are related in NAD+ precursor research.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | −20 °C or below | Dry, desiccated, protected from light |
| Aqueous solubility | High | Stability is pH- and temperature-dependent |
| Identity method | NMR spectroscopy | Confirms structure and anomeric form |
| Purity method | HPLC-UV or LC-MS | Measures assay and related substances |
| Common salt forms | Free acid; sodium salt | Counterion changes mass and hygroscopicity |
NMN is a polar, water-soluble nucleotide. In solid form it is usually a white to off-white powder. The compound is sensitive to heat, light, moisture, and extremes of pH, and aqueous solutions tend to degrade faster than dry material. Recommended storage for research samples is typically -20 °C or below in a sealed, desiccated container protected from light. Repeated freeze-thaw cycles should be avoided, and these handling practices help maintain identity and purity during laboratory use.
Analytical identification of NMN commonly uses high-performance liquid chromatography with ultraviolet detection, liquid chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy; HPLC can estimate purity by peak area, while mass spectrometry confirms molecular mass and fragmentation. NMR provides structural confirmation. Because NMN is charged, ion-pairing reagents or hydrophilic interaction liquid chromatography columns can improve retention and peak shape. In biological samples, LC-MS/MS with stable isotope internal standards is often used to quantify NMN and related NAD+ metabolites. Method validation is important because matrix effects and rapid enzymatic interconversion can complicate measurements.
Dietary sources of NMN include small amounts in certain vegetables, fruits, and other foods, although exact values vary by sample and method. Endogenous NMN concentrations are tightly regulated and often low, making measurement in blood or tissues technically demanding. After oral intake, NMN is thought to be rapidly metabolized in the intestine and liver, and intact NMN may not reach all tissues at high levels. Some rodent studies report increases in tissue NAD+ after oral NMN, while human data remain limited and sometimes rely on blood NAD+ metabolites rather than direct tissue measures.
Research on NMN has focused on aging, metabolic regulation, exercise capacity, and insulin sensitivity, but findings are preliminary. Many human trials are small, short in duration, and use different endpoints, which complicates comparison across studies. No national regulator has approved NMN as a therapeutic drug for any indication. In some countries it is sold as a supplement or research chemical, while other jurisdictions have questioned its status under food or supplement laws. Claims about extending human lifespan or reversing aging are not supported by established clinical evidence.
Nicotinamide mononucleotide, abbreviated NMN, is a naturally occurring nucleotide found in the cells of many organisms, including bacteria, plants, and mammals. Its structure consists of a nicotinamide ring attached to a ribose-phosphate group. NMN functions as an intermediate in the NAD+ salvage pathway, a recycling route that regenerates nicotinamide adenine dinucleotide. The enzyme nicotinamide phosphoribosyltransferase produces NMN from nicotinamide and phosphoribosyl pyrophosphate. A second enzyme, NMN adenylyltransferase, then converts NMN into NAD+.
Regulatory treatment of NMN differs by country and has changed over time. In the United States, the Food and Drug Administration has stated that NMN is excluded from the definition of a dietary supplement because it was investigated as a drug before being marketed as a supplement; enforcement and legal interpretation continue to evolve. In the European Union, NMN may require authorization as a novel food before sale. In Japan, NMN has been marketed in some food products, while it is not approved as a therapeutic drug in major markets. These categories affect labeling, permitted claims, and quality oversight.
Solid NMN is generally handled as a moisture-sensitive and light-sensitive material. Suppliers commonly recommend storage at minus 20 degrees Celsius in a sealed, desiccated container, protected from light. Aqueous solutions are less stable than the solid and may degrade faster at elevated temperatures or extreme pH values. Because NMN contains a phosphate ester and a glycosidic bond, hydrolysis and other degradation pathways are plausible under unfavorable conditions. Stability data from independent laboratories remain limited, so handling recommendations often reflect supplier practice rather than published consensus.
Analytical measurement of NMN typically uses high-performance liquid chromatography with ultraviolet detection, often at a wavelength near 260 nanometers. Liquid chromatography coupled with tandem mass spectrometry provides greater sensitivity and specificity, especially for biological samples. Nuclear magnetic resonance spectroscopy can confirm structure and detect certain impurities. Purity values reported by suppliers depend on the analytical method, calibration standards, and whether related compounds such as nicotinamide or NAD+ are included in the calculation. Independent verification is useful because supplement labels may not fully describe the tested material.
== Production == Selenoproteins, like regular proteins, are made by the ribosome, which requires residues to be carried by tRNAs. Selenocystine (Sec) has its special tRNASec for this purpose. This tRNA, unlike other tRNAs, is not directly loaded with the selenocystyl residue from a free Sec molecule; instead, it is first loaded with a seryl residue from serine by the conventional seryl-tRNA synthase (forming Ser-tRNASec), then an enzyme converts this seryl into a selenocystyl residue, forming Sec-tRNASec. In bacteria, L-seryl-tRNASec selenium transferase (SelA) performs this work using the selenium provided by selenophosphate. In archaea and eukarya, this happens first by phosphoseryl-tRNA kinase attaching a phosphate group to the seryl, then by SLA/LP converting the phosphoseryl to selenocystyl with the help of selenophosphate. The structure of tRNASec is different from typical (canonical) tRNAs by the lengthening of the D-stem and a very long variable loop. This prevents the usual EF-Tu (eEF1A in eukaryotes) from recognizing the tRNA. Instead, a special elongation factor called SelB is needed to help the ribosome use Sec-tRNASec. SelB consists of two protein domains: the N-terminal part is highly homologous to EF-Tu and serves to provide the elongation action, and the C-terminal part serves to recognize the SECIS element on the mRNA coding for the selenoprotein. Together, the two parts allow SelB to carry the Sec-tRNASec to the ribosome's A site for the UGA codon to be decoded. In bacteria, the SECIS element occurs soon after the UGA codon it activates.
== Illness and death == In June 2026, Chase was admitted to the Los Angeles General Medical Center for treatment of severe malnutrition following a period of extreme weight loss. During her hospitalization, her condition became increasingly critical after she was diagnosed with bacterial meningitis, several bloodstream infections, and AIDS. Doctors stated that she did not have much time left to live. To help manage rising medical expenses and support Chase in regaining stability, her alleged boyfriend, Roy Hernandez, created a GoFundMe crowdfunding campaign. In the campaign description, Hernandez said that Chase had faced significant personal difficulties in her post-acting life, including systemic bullying, a painful estrangement from her family, and ongoing housing instability in downtown Los Angeles. Chase died hours after the fundraising page was launched on June 16, from organ failure caused by her infections, substance abuse and AIDS. She was 35. A secondary cause of death was chronic polysubstance use. Hernandez publicly announced her death through TMZ the following day, June 17, stating that her bloodstream infections had led to septic complications that caused her body to shut down. Following her death, a dispute emerged regarding her final arrangements and the crowdfunding campaign, which Hernandez claimed was intended to help fund her cremation. Chase's former manager, John Ryan, and her father, John Schwallier, publicly denounced the fundraiser, advising fans not to donate.
== Structure == CDPSs don’t have a specific structure, given each one has its own specific function, but they still have common architectures, such as a Rossmann-fold domain. CDPSs are monomers that have been found to display a strong structural similarity to the catalytic domains of class Ic aminoacyl tRNA synthetases: both these families, CDPSs and class Ic aaRSs, have a Rossmann-fold domain and their structures can be superimposed showing many structural analogies. CDPSs characteristically feature a deep surface-accessible pocket bordered by the catalytic residues, which is where the catalysis of amide bond formation takes place. This structure is positioned similarly to the aminoacyl binding pocket in aaRSs, which leads to thinking that CDPSs evolved from class Ic aaRSs. CDPSs and aaRSs present substantial differences though, such as the absence of ATP-binding motifs in CDPSs, given that these use, unlike aaRSs, amino acids that have already been activated.
== Background == The skin is the largest organ in the human body. Skin is made up of three layers, the epidermis, dermis and the fat layer, also called the hypodermis. The epidermis is the outer layer of skin that keeps vital fluids in and harmful bacteria out of the body. The dermis is the inner layer of skin that contains blood vessels, nerves, hair follicles, oil, and sweat glands. Traditional ways of dealing with large losses of skin have been to use skin grafts from the patient (autografts) or from an unrelated donor or a cadaver. The former approach has the disadvantage that there may not be enough skin available, while the latter suffers from the possibility of rejection or infection. Until the late 20th century, skin grafts were constructed from the patient's own skin. This became a problem when skin had been damaged extensively, making it impossible to treat severely injured patients with autografts only.
Sources: en.wikipedia.org
=== 2014–present: Return to acting and resurgence === Larter returned to the big screen playing Molly Kingston, the love interest of Charlie Darby, a successful but psychotic man (Matt LeBlanc) in the comedy Lovesick (2014). The film screened at the 15th annual Newport Beach Film Festival in Newport Beach, California and was released for VOD and selected theaters. She portrayed Keely, the "fair-weather" friend of Kate Parker (Hilary Swank), a woman with ALS in the independent drama You're Not You (2014), directed by George C. Wolfe. Her co-stars were Emmy Rossum and Josh Duhamel. In 2014, Larter obtained a regular part in the first season of TNT's drama series Legends, appearing as Crystal McGuire, an operative with the FBI's Deep Cover Operations. She starred in the supernatural thriller The Diabolical as Madison, a single mother who battles evil forces in her house. Released in 2015 at South by Southwest in Austin, Texas, it was distributed for a VOD and limited release in only certain parts of the United States. The film received largely mixed reviews; Gary Goldstein of the Los Angeles Times felt that her "fraught, more seemingly complex [character] remains underdeveloped" in what he described as a "weak horror-thriller". Larter starred in Resident Evil: The Final Chapter (2016), where her role of Claire teams up with Alice (Jovovich) and the Red Queen (Ever Anderson) to save the remnants of humanity. Despite a largely mixed critical response it grossed over $312 million worldwide. The film is Larter's biggest box office success.
An autoimmune disease is a condition causing disease that results from an anomalous response of the adaptive immune system, wherein it mistakenly targets and attacks healthy, functioning parts of the body as if they were foreign organisms. It is estimated that there are more than 80 recognized autoimmune diseases, with recent scientific evidence suggesting the existence of potentially more than 100 distinct conditions. Nearly any body part can be involved. Autoimmune diseases are a separate class from autoinflammatory diseases. Both are characterized by an immune system malfunction which may cause similar symptoms, such as rash, swelling, or fatigue, but the cardinal cause or mechanism of the diseases is different. A key difference is a malfunction of the innate immune system in autoinflammatory diseases, whereas in autoimmune diseases there is a malfunction of the adaptive immune system. Symptoms of autoimmune diseases can significantly vary, primarily based on the specific type of the disease and the body part that it affects. Symptoms are often diverse and can be fleeting, fluctuating from mild to severe, and typically comprise low-grade fever, fatigue, and general malaise. However, some autoimmune diseases may present with more specific symptoms such as joint pain, skin rashes (e.g., urticaria), or neurological symptoms. The exact causes of autoimmune diseases remain unclear and are likely multifactorial, involving both genetic and environmental influences.
James Rowley French (September 23, 1928 – December 20, 2017) was an American radio host, voice actor, writer and producer. French founded Imagination Theatre in 1996 and served as its producer until 2017. He was the morning DJ on the Seattle radio station KIRO from 1959 to 1971, and again from 1980 to 1994. As a voice actor, French was known for his work in video games by Valve, including Half-Life 2 (2004), Left 4 Dead (2008), and Dota 2 (2013).
Sources: en.wikipedia.org
As carbon dioxide concentrations rise, the rate at which sugars are made by the light-independent reactions increases until limited by other factors. RuBisCO, the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. However, if the carbon dioxide concentration is low, RuBisCO will bind oxygen instead of carbon dioxide. This process, called photorespiration, uses energy, but does not produce sugars. RuBisCO oxygenase activity is disadvantageous to plants for several reasons:
However, after the Qualifying Final between Collingwood and West Coast was drawn and replayed, Essendon lost to Collingwood in both the second semi-final and the grand final. Following the 1991 season, Essendon moved its home games from its traditional home ground at Windy Hill to the larger and newly renovated MCG. This move generated large increases in game attendances, memberships and revenue for the club. The club's training and administrative base remained at Windy Hill until 2013. Following the retirement of Tim Watson and Simon Madden in the early 1990s, the team was built on new players such as Gavin Wanganeen, Joe Misiti, Mark Mercuri, Michael Long, Dustin Fletcher (son of Ken) and James Hird, who was taken at No. 79 in the 1990 draft. This side became known as the "Baby Bombers", as the core of the 1993 premiership side was made up of young players early in their careers. The team won the 1993 Grand Final against Carlton and that same year, Gavin Wanganeen won the Brownlow Medal, the first awarded to an Essendon player since 1976. Three years later, James Hird was jointly awarded the medal with Michael Voss of Brisbane. In 2000, the club shifted the majority of its home games to the newly opened Docklands Stadium, signing a 25-year deal to play seven home matches per year at the venue, with the other four remaining at the MCG. The season was one of the most successful by any team in VFL/AFL history, and the club opened with 20 consecutive wins before they lost to the Western Bulldogs in round 21.
Dental treatment (e.g. dentoalveolar surgery/procedure that impacts bone) – it is possible for MRONJ to occur spontaneously without any recent invasive dental treatment Duration of bisphosphonate drug therapy – increased risk with increased cumulative dose of drug Other concurrent medication – use of chronic systemic glucocorticoid increases risk when they are taken in combination with anti-resorptive drugs Dental implants Drug holidays – no evidence to support a reduction in MRONJ risk if patients stop taking bisphosphonates temporarily/permanently, as drugs can persist in skeletal tissues for many years Treatment in the past with anti-resorptive/anti-angiogenic drugs Patient being treated for cancer – higher risk Patients being treated for osteoporosis/non-malignant bone diseases (e.g. Paget's disease) – lower risk
1885: Berries from Norfolk, Virginia, were shipped by refrigerator car to New York. 1887: Parker Earle joined F.A. Thomas of Chicago in the fruit shipping business. The company owned 60 ice-cooled railcars by 1888, and 600 by 1891. 1888: Armour & Co. shipped beef from Chicago to Florida in a car cooled by ethyl chloride-compression machinery. Florida oranges were shipped to New York under refrigeration for the first time. 1889: The first cooled shipment of fruit from California was sold on the New York market. 1898: Russia's first refrigerator cars entered service. The country's inventory reached 1,900 by 1908, 3,000 two years later, and peaked at approximately 5,900 by 1916. The cars were used mainly for transporting butter from Siberia to the Baltic Sea, a 12-day journey. 1899: Refrigerated fruit traffic within the U.S. reached 90,000 short tons (81,647 t; 80,357 long tons) per year; Transport from California to New York averaged 12 days in 1900. 1901: Carl von Linde equipped a Russian train with a mobile, central mechanical refrigeration plant to distribute cooling to cars carrying perishable goods. Similar systems were used in Russia as late as 1975. 1905: U.S. traffic in refrigerated fruit reached 430,000 short tons (390,089 t; 383,929 long tons). As refrigerator car designs became standardized, the practice of indicating the "patentee" on the sides was discontinued. 1907: The Pacific Fruit Express began operations with more than 6,000 refrigerated cars, transporting fruit and vegetables from Western producers to Eastern consumers. U.S.
Sources: en.wikipedia.org
Purity is commonly measured by high-performance liquid chromatography with ultraviolet or mass spectrometric detection. Nuclear magnetic resonance can confirm identity and anomeric composition. Water content and residual solvents may be tested separately.
Dry NMN is typically stored refrigerated or frozen in a desiccated container. Solutions are less stable and should be kept cold and used promptly. Protection from light and moisture helps limit degradation.
Beta-NMN is the naturally occurring anomer involved in NAD+ production. Alpha-NMN can form during synthesis and is often tracked as an impurity. Analytical methods such as NMR or HPLC can distinguish the two forms.
NMN is nicotinamide mononucleotide, a nucleotide intermediate in NAD+ biosynthesis. It consists of nicotinamide, ribose, and phosphate groups.