lyophilized powder is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-05-27. Where a claim depends on a specific study, the study is described rather than over-claimed.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
Solid material is normally kept at minus 20 degrees Celsius in a sealed, desiccated container. Reconstituted solutions are less stable and are usually divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of activity. Light exposure is minimized by using amber glassware or foil wrapping. Published stability data for this peptide are sparse, so recommended storage conditions rest mainly on general practice for short synthetic peptides rather than on dedicated study.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Seven-residue peptide |
| Molecular mass | 813.9 Da | Monoisotopic value |
| Appearance | White to off-white powder | Lyophilized form |
| Solubility | Freely soluble in water | Also soluble in saline and polar solvents |
| Storage (dry) | -20 °C or lower | Desiccated, protected from light |
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
== Secretion == A typical adult human stomach will secrete about 1.5 liters of gastric juice daily. Gastric juice is the combination of gastric gland secretions including the main component of hydrochloric acid (gastric acid), gastric lipase and pepsinogen. Once in the stomach pepsinogen is changed by gastric acid to the digestive enzyme pepsin adding this enzyme to the gastric juice. In humans, the pH of gastric acid is between one and three, much lower than most other animals, but is very similar to that of carrion eating carnivores, needing extra protection from ingesting pathogens. Gastric acid secretion is produced in several steps. Chloride and hydrogen ions are secreted separately from the cytoplasm of parietal cells and mixed in the canaliculi. This creates a negative potential of between −40 and −70 mV across the parietal cell membrane that causes potassium ions and a small number of sodium ions to diffuse from the cytoplasm into the parietal cell canaliculi. Gastric acid is then secreted along with other gland secretions into the gastric pit for release into the stomach lumen. The enzyme carbonic anhydrase catalyses the reaction between carbon dioxide and water to form carbonic acid. This acid immediately dissociates into hydrogen and bicarbonate ions. The hydrogen ions leave the cell through H+/K+ ATPase antiporter pumps. At the same time, sodium ions are actively reabsorbed. This means that the majority of secreted K+ (potassium) and Na+ (sodium) ions return to the cytoplasm.
=== 1990s === 1994: divests its Waters Chromatography Division to focus on its membrane business 1996: acquires Amicon separation sciences business from W. R. Grace and Company 1997: acquires Tylan General, expanding its gas purification offerings for the microelectronics industry 1999: acquires Bioprocessing Limited, a developer and manufacturer of chromatography
Since most of the dissolved CO2 remains as CO2 molecules, Ka1(apparent) has a much larger denominator and a much smaller value than the true Ka1. The bicarbonate ion is an amphoteric species that can act as an acid or as a base, depending on pH of the solution. At high pH, it dissociates significantly into the carbonate ion (CO32–):
=== InPen === The InPen is a reusable, bluetooth-enabled insulin pen, manufactured by Medtronic, that can connect to Dexcom CGM systems. The InPen can connect to the G6 and G7 through the InPen app, the Apple iPhone's Heath app, and on the Apple Watch.
Sources: en.wikipedia.org
=== Optimization of protein crystallization conditions === Although proteins are dynamic structures in solution, formation of protein crystals is expected to be favored when all molecules lie in their lowest energy conformation. Thermofluor evaluation of conditions that stabilize proteins is consequently a useful strategy for finding optimal crystallization conditions
== Family == In 1890, Thomson married Rose Elisabeth Paget at the church of St Mary the Less. Rose, who was the daughter of Sir George Edward Paget, a physician and then Regius Professor of Physic at Cambridge, was interested in physics. Beginning in 1882, women could attend demonstrations and lectures at the University of Cambridge. Rose attended demonstrations and lectures, among them Thomson's, leading to their relationship. They had two children: George Paget Thomson, who was also awarded a Nobel Prize for his work on the wave properties of the electron; and Joan Paget Thomson (later Charnock), who became an author—writing children's books, non-fiction, and biographies.
== Medical uses == In the United States, anacaulase gel is indicated for eschar removal in adults with deep partial thickness and/or full thickness thermal burns. The medication is approved for burns of degrees IIb, i.e. deep partial skin thickness burns, to III, i.e. full thickness burns, and has been shown to significantly reduce the necessity of surgical debridement (15% versus 63% under standard treatment) and skin transplants (18% versus 34%) in a randomized controlled trial. The concentrate is solved in a sterile gel basis, applied onto the burn wound, covered with a wound dressing, and removed after four hours. The healthy surrounding skin has to be protected with a sterile paraffin ointment. The EMA recommends that the treatment should be used only in hospitals having specialised burns centres.
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Miscellaneous: Cellulose can be converted into cellophane, a thin transparent film. It is the base material for the celluloid that was used for photographic and movie films until the mid-1930s. Cellulose is used to make water-soluble adhesives and binders such as methyl cellulose and carboxymethyl cellulose which are used in wallpaper paste. Cellulose is further used to make hydrophilic and highly absorbent sponges. Cellulose is the raw material in the manufacture of nitrocellulose (cellulose nitrate) which is used in smokeless gunpowder. Pharmaceuticals: Cellulose derivatives, such as microcrystalline cellulose (MCC), have the advantages of retaining water, being a stabilizer and thickening agent, and in reinforcement of drug tablets.
Sources: en.wikipedia.org
It is a synthetic peptide of seven amino acids. Its backbone corresponds to a fragment of adrenocorticotropic hormone extended at the carboxyl end. The material is distributed as a lyophilized solid for laboratory use.
The extension was introduced to slow enzymatic breakdown of the peptide in biological systems. Natural ACTH fragments are degraded rapidly by peptidases. Adding the tripeptide was intended to extend the window during which the molecule remains intact.
Most published work consists of animal experiments conducted in a small number of laboratories. Human data are limited in number and size. Whether the observed effects translate into reliable clinical benefit is still unresolved.
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.