If you have been reading about Methionine oxidation 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.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
| Property | Value | Notes |
|---|---|---|
| Primary research models | Rodent studies | Largest share of published data |
| Reported markers | BDNF and NGF expression | Measured mainly in animal tissue |
| Common administration | Intranasal | Matches the registered formulation |
| Blood residence time | Minutes | Rapid enzymatic degradation |
| Evidence quality | Small trials, limited replication | Noted repeatedly in reviews |
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
=== 13 May === Moments before Ukraine's entry to the Eurovision Song Contest 2023, Tvorchi, were due to perform in Liverpool in the United Kingdom, their hometown of Ternopil was struck by Russian missiles, injuring two people and damaging warehouses. This prompted them to close their performance with a message for solidarity with Ukraine. 11 people were also injured in overnight drone attacks in Khmelnytskyi. The Ukrainian military said that 18 out of 22 Iranian Shahed-131/136 drones were shot down in the attacks. Russia accused Ukraine of attacking the occupied city of Luhansk with its newly acquired British Storm Shadow missiles, wounding six children. It also claimed to have downed two Ukrainian aircraft, an Su-24 and a MiG-29, that launched the missiles. The Russian Defence Ministry said that Russian forces had seized a block in Bakhmut. Two Russian helicopters, both Mi-8s, and two Russian fighters, an Su-34 and an Su-35, crashed in Bryansk Oblast, near the border with Ukraine with no survivors. Nine personnel were said to have been killed. The Russian newspaper Kommersant reported that the aircraft were on their way for a bombing run in neighboring Chernihiv Oblast when they were shot down by Ukrainian forces, which was also echoed by Russian pro-military bloggers. The Russian state news agency TASS only reported the loss of an Su-34 warplane without providing a reason, as well as that of a helicopter due to an engine fire near Klintsy, about 40 km (25 mi) from the international border.
The transcription factor p63, which prevents epidermal stem cells from differentiating into keratinocytes. Mutations in the p63 DNA-binding domain are associated with ectrodactyly, ectodermal dysplasia, and cleft lip/palate (EEC) syndrome. The transcriptome of p63 mutant keratinocytes deviated from the normal epidermal cell identity. Vitamin A and its analogues. Epidermal growth factor. Transforming growth factor alpha. Cholera toxin.
The microstructure of a polymer (sometimes called configuration) relates to the physical arrangement of monomer residues along the backbone of the chain. These are the elements of polymer structure that require the breaking of a covalent bond in order to change. Various polymer structures can be produced depending on the monomers and reaction conditions: A polymer may consist of linear macromolecules containing each only one unbranched chain. In the case of unbranched polyethylene, this chain is a long-chain n-alkane. There are also branched macromolecules with a main chain and side chains, in the case of polyethylene the side chains would be alkyl groups. In particular unbranched macromolecules can be in the solid state semi-crystalline, crystalline chain sections highlighted red in the figure below. While branched and unbranched polymers are usually thermoplastics, many elastomers have a wide-meshed cross-linking between the "main chains". Close-meshed crosslinking, on the other hand, leads to thermosets. Cross-links and branches are shown as red dots in the figures. Highly branched polymers are amorphous and the molecules in the solid interact randomly.
== Atmospheric cold traps == In atmospheric science, a cold trap is a region of the atmosphere that is substantially colder than the layers below it. For example, in Earth's tropical tropopause layer, air temperature drops with increasing height until it reaches a minimum cold point. This region acts as a cold trap because it dehydrates ascending air masses. As water vapor rises from the troposphere, the extreme cold forces it to freeze into ice crystals, which gravitationally settle back into the lower atmosphere before they can reach the stratosphere. For biological life on Earth, the atmospheric cold trap plays a critical role in preserving the planet's water supply over geological timescales. At the temperature minimum of the tropopause, ascending moist air is effectively freeze-dried to its equilibrium water vapor concentration, strictly limiting the abundance of water at stratospheric altitudes where photolysis occurs. Without this cold trap mechanism to confine moisture to the lower atmosphere, water vapor would freely ascend into the upper atmosphere and undergo photolysis via intense solar ultraviolet radiation, causing the lighter hydrogen atoms to permanently escape into space. Planetary scientists attribute the extreme dryness of Venus to the historical absence of an atmospheric cold trap. In a warm, primitive Venusian atmosphere, a high surface concentration of water vapor would bypass condensation, elevating the mixing ratio at the cold trap and allowing moisture to freely ascend into the upper atmosphere where hydrogen escaped into space.
There were a few similar spark discharge experiments contemporaneous with Miller–Urey. An article in The New York Times (March 8, 1953) titled "Looking Back Two Billion Years" describes the work of Wollman M. MacNevin at Ohio State University, before the Miller Science paper was published in May 1953. MacNevin was passing 100,000V sparks through methane and water vapor and produced "resinous solids" that were "too complex for analysis." Furthermore, K. A. Wilde submitted a manuscript to Science on December 15, 1952, before Miller submitted his paper to the same journal in February 1953. Wilde's work, published on July 10, 1953, used voltages up to only 600V on a binary mixture of carbon dioxide (CO2) and water in a flow system and did not note any significant reduction products. According to some, the reports of these experiments explain why Urey was rushing Miller's manuscript through Science and threatening to submit to the Journal of the American Chemical Society. By introducing an experimental framework to test prebiotic chemistry, the Miller–Urey experiment paved the way for future origin of life research. In 1961, Joan Oró produced milligrams of the nucleobase adenine from a concentrated solution of HCN and NH3 in water. Oró found that several amino acids were also formed from HCN and ammonia under those conditions. Experiments conducted later showed that the other RNA and DNA nucleobases could be obtained through simulated prebiotic chemistry with a reducing atmosphere.
Sources: en.wikipedia.org
A myristic acid molecule is attached to this analogue, which associates the insulin molecule to the abundant serum albumin, which in turn extends the effect and reduces the risk of hypoglycemia. Both protracted analogues need to be taken only once daily, and are used for type 1 diabetics as the basal insulin. A combination of a rapid acting and a protracted insulin is also available, making it more likely for patients to achieve an insulin profile that mimics that of the body's own insulin release. Insulin is also used in many cell lines, such as CHO-s, HEK 293 or Sf9, for the manufacturing of monoclonal antibodies, virus vaccines, and gene therapy products. Insulin is usually taken as subcutaneous injections by single-use syringes with needles, via an insulin pump, or by repeated-use insulin pens with disposable needles. Inhaled insulin is also available in the U.S. market. Those who take insulin may choose a particular method of administration for improved blood glucose control, discrete delivery, comfort, or cost, among a variety of other factors. Unlike many medicines, insulin cannot be taken by mouth because, like nearly all other proteins introduced into the gastrointestinal tract, it is reduced to fragments, whereupon all activity is lost. There has been some research into ways to protect insulin from the digestive tract, so that it can be administered orally or sublingually. In 2021, the World Health Organization added insulin to its model list of essential medicines.
Bayer lost some of its trademark rights to heroin (as well as aspirin) under the 1919 Treaty of Versailles following the German defeat in World War I. Use of heroin by jazz musicians in particular was prevalent in the mid-twentieth century, including Billie Holiday, saxophonists Charlie Parker, John Coltrane and Art Pepper, trumpeter and vocalist Chet Baker, guitarist Joe Pass and piano player/singer Ray Charles; a "staggering number of jazz musicians were addicts". It was also a problem with many rock musicians, particularly from the late 1960s through the 1990s. Pete Doherty is also a self-confessed user of heroin. Nirvana lead singer Kurt Cobain's heroin addiction was well documented. Pantera frontman Phil Anselmo turned to heroin while touring during the 1990s to cope with his back pain. Lou Reed's heroin addiction is well known and evident by the many references to the drug in his songs. James Taylor, Taylor Hawkins, Jimmy Page, John Lennon, Eric Clapton, Johnny Winter, Keith Richards, Shaun Ryder, Shane MacGowan and Janis Joplin also used heroin. Many musicians have made songs referencing their heroin usage.
The application of LA-ICPMS in U-Pb geochronology started in the 1990s. Since it enables relatively short and cheap yet high-spatial-resolution analysis, it has become the most utilized method of monazite geochronology. The precision of LA-ICPMS is limited by standard variability, which is about 2% of a given age. The mineral sample surface is sputtered by a laser inside a sample cell. The ablated particles are collected and incorporated into a carrier gas. The resulting aerosols are analyzed by a mass spectrometer for dating. A solid-state or gas-source laser with a short wavelength is commonly used as the laser ablation system in geochronology.
One of the more significant examples of the implementation of containment was the United Nations US-led intervention in the Korean War. In June 1950, after years of mutual hostilities, Kim Il Sung's North Korean People's Army invaded South Korea. Stalin had been reluctant to support the invasion but ultimately sent advisers. To Stalin's surprise, the United Nations Security Council backed the defense of South Korea, although the Soviets were then boycotting meetings in protest of the fact that Taiwan (Republic of China), not the People's Republic of China, held a permanent seat on the United Nations Security Council. A UN force of sixteen countries faced North Korea, although 40 percent of troops were South Korean, and about 50 percent were from the United States.
=== October === October 10, 2008: Singapore First Asian country to slip into a recession since the credit crisis began. Singapore's export-dependent economy shrank an annualized 6.3% in the third quarter after a revised 5.7% contraction in the second quarter; its first recession since 2002. Growth has faltered in Singapore as a result of less demand for exports, a reduction in tourism, and the end of the real-estate boom. Singapore's manufacturing sector had declined 4.9% in the previous quarter.
Sources: en.wikipedia.org
The main proposal is modulation of neurotrophic factors such as brain-derived neurotrophic factor, supported largely by animal experiments. Receptor-level targets have not been firmly established. Most reviews describe the mechanism as only partially characterized.
The compound is registered as a medicine in Russia, so clinical work has concentrated there. Trials elsewhere are few and generally small. This geographic concentration is a recognized limitation in evidence reviews.
Some fraction may reach the central nervous system through olfactory pathways, and this is often cited as the rationale for the nasal route. The size of that fraction in humans is not well quantified. Blood concentrations after nasal dosing are low, which complicates measurement.
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.