The short version of ACTH(4-10) fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-05-25. Anything still debated is marked as such rather than presented as settled.
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.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
| 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 |
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
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。
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
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。
== Plasticity == Cell plasticity is the idea that cells can switch phenotypes in response to environmental cues. In the context of regeneration, this environmental cue is damage or injury to a limb. Cell plasticity is closely related to dedifferentiation, implying that a cell with ‘plasticity’ can dedifferentiate to change phenotypes. Cell plasticity suggests that cells can change phenotypes slightly; not fully de-differentiating, to serve a better function. A strong example of this is lens regeneration in the newt.
=== October === 1 October – A ban on single-use plastic cutlery, plates and polystyrene trays comes into force in England. 2 October – NHS doctors in England begin a 72-hour strike as their dispute over pay and conditions continues. Education Secretary Gillian Keegan announces plans to ban pupils from using mobile phones at schools, both in lessons and during breaktime. A gas tank explodes at the Severn Trent Green Power site in Cassington, Oxfordshire, after it is struck by lightning. A boy is taken to hospital in a critical condition along with a man in his 50s after both are hit by lightning during a football match at The Sele School in Hertford. 3 October – Appearing at Sheffield Crown Court, a 13-year-old boy admits causing the death of Marcia Grant, 60, by running her over with her own car in the Greenhill area of Sheffield in April 2023. Following a trial at Worcester Crown Court, food processing factory worker Garry Jones, who contaminated food destined for Nando's with plastic gloves, plastic bags and metal ring pulls is sentenced to three years in prison. 4 October – Sunak confirms plans to replace A Levels and T Levels in England with a new qualification called the Advanced British Standard. 5 October – Historic England says it has discovered damage to Hadrian's Wall next to the felled Sycamore Gap Tree. An inquest is opened and adjourned into the M53 motorway coach crash. 8 October – Part of the Grade II listed Old Courthouse in Cockermouth, Cumbria, collapses into the River Cocker.
=== Macrocyclic CSPs === An interesting way of achieving chiral distinction on a CSP is the use of selectors with chiral cavity. These chiral selectors are attached to the stationary phase support material. In this category, there are basically three types of cavity chiral selectors namely cyclodextrins, crown ethers and macrocyclic glycopeptide antibiotics. Among these cyclodextrin based CSP is popular. In this type of CSPs the enantioselective guest-host interaction governs the chiral distinction.
=== Combinatorial extension === The combinatorial extension (CE) method is similar to DALI in that it too breaks each structure in the query set into a series of fragments that it then attempts to reassemble into a complete alignment. A series of pairwise combinations of fragments called aligned fragment pairs, or AFPs, are used to define a similarity matrix through which an optimal path is generated to identify the final alignment. Only AFPs that meet given criteria for local similarity are included in the matrix as a means of reducing the necessary search space and thereby increasing efficiency. A number of similarity metrics are possible; the original definition of the CE method included only structural superpositions and inter-residue distances but has since been expanded to include local environmental properties such as secondary structure, solvent exposure, hydrogen-bonding patterns, and dihedral angles. An alignment path is calculated as the optimal path through the similarity matrix by linearly progressing through the sequences and extending the alignment with the next possible high-scoring AFP pair. The initial AFP pair that nucleates the alignment can occur at any point in the sequence matrix. Extensions then proceed with the next AFP that meets given distance criteria restricting the alignment to low gap sizes. The size of each AFP and the maximum gap size are required input parameters but are usually set to empirically determined values of 8 and 30 respectively.
== Use and effects == According to Alexander Shulgin, nor-LSD showed no psychedelic effects at assessed doses of up to 500 μg in humans, whereas LSD was active at doses as low as 50 μg. Higher doses of nor-LSD do not appear to have been assessed.
Sources: en.wikipedia.org
Like all parvoviruses, FPLV is extremely resistant to inactivation and can survive for longer than one year in a suitable environment. Kitten deaths have been reported in households of fully vaccinated cats, possibly because of exposure to large amounts of virus in the environment. In a recent study, microRNA responses to FPLV infection were identified in feline kidney cells by sequencing, providing a possible link between miRNA expression and pathogenesis of FPV infection. Infection occurs when the virus enters the body through the mouth or nose. Whether illness results or not depends on the immunity in the victim vs. the number of individual virus particles (i.e. the amount of virus) entering the body.
=== Legal status === In employment discrimination law in the United States, employers are generally allowed to consider characteristics that would otherwise be discriminatory if they are bona fide occupational qualifications (BFOQ). For example, a manufacturer of men's clothing may lawfully advertise exclusively for male models. Hooters has argued a BFOQ defense, which applies when the "essence of the business operation would be undermined if the business eliminated its discriminatory policy".
The US lost two nuclear submarines during this time: USS Thresher due to equipment failure during a test dive while at its operational limit, and USS Scorpion due to unknown causes. During the Indo-Pakistani War of 1971, the Pakistan Navy's Hangor sank the Indian frigate INS Khukri. This was the first sinking by a submarine since World War II. During the same war, Ghazi, a Tench-class submarine on loan to Pakistan from the US, was sunk by the Indian Navy. It was the first submarine combat loss since World War II. In 1982 during the Falklands War, the Argentine cruiser General Belgrano was sunk by the British submarine HMS Conqueror, the first sinking by a nuclear-powered submarine in war. Some weeks later, on 16 June, during the Lebanon War, an unnamed Israeli submarine torpedoed and sank the Lebanese coaster Transit, which was carrying 56 Palestinian refugees to Cyprus, in the belief that the vessel was evacuating anti-Israeli militias. The ship was hit by two torpedoes, managed to run aground but eventually sank. There were 25 dead, including her captain. The Israeli Navy disclosed the incident in November 2018.
However, it is possible that some isotopes that are now considered stable will be revealed to decay with extremely long half-lives (as happened with bismuth). For each of the 80 stable elements, the number of stable isotopes is given. Only 90 isotopes are stable against any possible decay, and an additional 161 are energetically unstable (see List of nuclides) but have never been observed to decay. Thus, 251 isotopes (nuclides) are stable by definition (including an excited state, tantalum-180m, for which no decay has yet been observed). In April 2019 it was announced that the half-life of xenon-124 had been measured to 1.8 × 1022 years. This is the longest half-life directly measured for any unstable isotope; only the (indirectly measured) half-life of tellurium-128 is longer. Of the chemical elements, only 1 element (tin) has 10 such stable isotopes, 5 have 7 stable isotopes, 7 have 6 stable isotopes, 11 have 5 stable isotopes, 9 have 4 stable isotopes, 5 have 3 stable isotopes, 16 have 2 stable isotopes, and 26 have 1 stable isotope. Additionally, 31 nuclides of the naturally occurring elements have unstable isotopes with a half-life long enough to have survived for the age of the Solar System (108 years or more), and an additional four such nuclides represent three elements (bismuth, thorium, uranium) having no stable isotope. These 35 radioactive naturally occurring nuclides comprise the radioactive primordial nuclides. The total number of primordial nuclides is then 251 (the stable nuclides) plus the 35 radioactive primordial nuclides, for a total of 286.
=== Intracrines and regenerative Medicine === The discovery of intracrine loops in stem cell regulation has profound implications for regenerative medicine. Because intracrines can establish long-lasting differentiation programs, they offer potential therapeutic targets for tissue regeneration and repair. For example, in cardiac repair, HMGB1 has been shown to enhance the proliferation and differentiation of cardiac stem cells following myocardial infarction, suggesting that modulating intracrine pathways could improve heart regeneration. The ability of certain intracrines to reprogram cells into pluripotent-like states also opens new avenues for regenerative therapies. Oct3/4, Sox2, and Nanog, all of which are involved in maintaining stem cell pluripotency, can potentially be introduced into cells to drive reprogramming without the need for genetic modification. This approach could provide safer and more controlled methods for generating patient-specific stem cells.
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 a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.