mass spectrometry 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 2026-01-12 and is reviewed periodically as new material appears.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Linear tetrapeptide, also written AEDG |
| Molecular mass | About 390.35 g/mol | Value calculated from the sequence |
| Appearance | White to off-white powder | Lyophilised material forms a loose cake |
| Solubility | Freely soluble in water | Also dissolves in isotonic saline |
| Storage | -20 °C, desiccated | Aliquot solutions to avoid freeze–thaw cycling |
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Eluxadoline, sold under the brand names Viberzi and Truberzi, is a medication taken by mouth for the treatment of diarrhea and abdominal pain in individuals with diarrhea-predominant irritable bowel syndrome (IBS-D). It was approved for use in the United States in 2015. The drug originated from Janssen Pharmaceutica and was developed by Actavis.
== Characteristics of drugs candidate to therapeutic drug monitoring == In pharmacotherapy, many medications are used without monitoring of blood levels, as their dosage can generally be varied according to the clinical response that a patient gets to that substance. For certain drugs, this is impracticable, while insufficient levels will lead to undertreatment or resistance, and excessive levels can lead to toxicity and tissue damage. Indications in favor of therapeutic drug monitoring include:
=== DPP-4 inhibitor trials === McGuire served on the executive committees of four cardiovascular outcome trials (CVOTs) evaluating DPP-4 inhibitors: SAVOR-TIMI 53 (saxagliptin), TECOS (sitagliptin), CAROLINA (linagliptin), and CARMELINA (linagliptin). He was co-chair of CARMELINA. These trials were designed to establish non-inferiority for major adverse cardiovascular events (MACE). SAVOR-TIMI 53 reported an increased risk of hospitalization for heart failure with saxagliptin.
=== 1960s === In November 30, 1960, Grace announced a multi-million dollar expansion of its polymer chemicals division. In December 1969, Grace sold Grace Shipping Company to Prudential Lines for $445 million.
=== Changing sleep position === More than half of people with obstructive sleep apnea have some degree of positional obstructive sleep apnea, meaning that it gets worse when they sleep on their backs. Sleeping on their sides is an effective and cost-effective treatment for positional obstructive sleep apnea.
Sources: en.wikipedia.org
Many drugs exist in the treatment of ADHD. Dextroamphetamine (Dexedrine, Dextrostat), Adderall, methylphenidate (Ritalin, Metadate, Concerta, Daytrana), and lisdexamfetamine (Vyvanse) block reabsorption of the catecholamines dopamine and norepinephrine through monoamine transporters (including NET), thereby increasing levels of these neurotransmitters in the brain. The strong selective norepinephrine reuptake inhibitor (NRI), atomoxetine (Strattera), has been approved by the U.S. Food and Drug Administration (FDA) to treat ADHD in adults. The role of the NET in ADHD is similar to how it works to ease the symptoms of depression. The NET is blockaded by atomoxetine and increases NE levels in the brain. It can work to increase one's ability to focus, decrease any impulsiveness, and lessen hyperactivity in both children and adults with ADHD.
== Side effects == Diazoxide interferes with insulin release through its action on potassium channels. Diazoxide is one of the most potent openers of the K+ ATP channels present on the insulin producing beta cells of the pancreas. Opening these channels leads to hyperpolarization of cell membrane, a decrease in calcium influx, and a subsequently reduced release of insulin. The US Food and Drug Administration (FDA) published a safety announcement in July 2015 highlighting the potential for development of pulmonary hypertension in newborns and infants treated with this drug. Diazoxide has been associated with development of hypertrichosis and stimulation of scalp hair growth.
=== Valve Corporation v. Rothschild === In 2015, Display Technologies LLC, one of several IP-holding companies owned by Leigh Rothschild, sued Valve over patent infringement. While the suit was dismissed by January 2016, Valve shortly followed by acquiring licenses to twenty patents owned across Rothschild's firms. Around 2022, another Rothschild company, Patent Asset Management, began sending Valve demands to buy new licenses to two of the patents Valve already had licensed. Valve filed a lawsuit against the company in 2023 under Washington state's Patent Troll Protection and Consumer Protection Acts. In the months that followed, at least three lawsuits were filed in Texas by Rothschild's companies against Valve accusing Valve of additional patent infringement. Valve argued these suits were retaliatory to their Washington suit, and requested them to be dismissed. In February 2026, a jury found in Valve's favor on all counts.
A study compared different particle sizes of oral micronized estradiol. A preparation with the smallest particles (mainly <0.6 μm) was found to have the most rapid absorption and the highest bioavailability. However, a sharp peak in estradiol levels, without an accompanying rise in estrone levels, was observed during the first 2 hours with this particle size. It was suggested that the smallest estradiol particles may have been absorbed by the lymphatic system, partially bypassing first-pass metabolism and resulting in very high initial estradiol levels. The preparations with the larger particle sizes (mainly <3.5 μm and <20 μm) were found to be absorbed more slowly, without a pronounced initial peak in estradiol levels. Levels of estradiol were more even and similar to physiological levels with these particle sizes. Differences in area-under-the-curve estradiol levels with the different particle sizes were relatively small. As such, micronization may improve absorption but does not necessarily improve therapeutic effect. Micronized estradiol is rapidly and completely absorbed with oral administration. This is true for oral doses of 2 mg and 4 mg, but absorption was found to be incomplete for an oral dose of 8 mg. This dose showed 76% of the expected bioavailability based on dose proportionality and area-under-the-curve levels, indicating a small deviation from linearity. The absolute bioavailability of oral micronized estradiol is approximately 5%, with a possible range of 0.1% to 12%. As such, the bioavailability of oral estradiol is very low even with micronization.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.
AEDG is the one-letter code for the four amino acids alanine, glutamate, aspartate and glycine in that order. The same molecule is written in three-letter form as Ala-Glu-Asp-Gly.
Identity is normally confirmed by mass spectrometry against the calculated mass of roughly 390.35 g/mol. Purity is then estimated by reversed-phase high-performance liquid chromatography with ultraviolet detection.
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.