A practical reference on ACTH fragment: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-10-04. Anything still debated is marked as such rather than presented as settled.
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
| Property | Value | Notes |
|---|---|---|
| Appearance | White lyophilized powder | Typical for synthetic peptides |
| Solubility | Freely soluble in water | Also soluble in saline |
| Storage temperature | -20 C or below | Protect from repeated freeze-thaw |
| Analytical method | Reverse-phase HPLC | Confirms purity and identity |
| Common synonym | ACTH(4-10) analog | Reflects structural origin |
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
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.
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.
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.
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.
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.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
Line 14: Since 10 September 2016, the Moscow Central Circle (MCC) renovated railroad (the former Moskovskaya Okruzhnaya Zheleznaya Doroga) has been operated as Line 14 of the Moscow Metro. This cone-shaped railroad opened in 1908 (as a freight-only railway from 1934 until the reopening in 2016). Line 11: Another circular metro line—the Big Circle Line (Bolshaya Koltsevaya Liniya)—opened its first stations in 2018 and the remaining stations in 2023. The Kakhovskaya-Savyolovskaya western half of the line was launched in late 2021. The outermost ring within the city is the Moscow Ring Road—often called the MKAD, an acronym for the Russian Московская Кольцевая Автомобильная Дорога—which forms the city's cultural boundary; it was established during the 1950s. It was built at ground level, rather than being elevated, so it forms a barrier to roads that would otherwise pass beneath it. (Before Moscow's 2012 expansion, the MKAD was considered an approximate city boundary.) Outside Moscow, some roads encompassing the city follow the same circular pattern as within city limits; notable examples are the Betonka roads (highways A107 and A108), originally constructed of concrete pads. To reduce traffic on the MKAD, a new ring road—called CKAD, Centralnaya Koltsevaya Avtomobilnaya Doroga, Central Ring Road—was completed outside the MKAD in 2021.
In this process, the superoxide anion is produced as a by-product of several steps in the electron transport chain. Particularly important is the reduction of coenzyme Q in complex III, since a highly reactive free radical is formed as an intermediate (Q·−). This unstable intermediate can lead to electron "leakage", when electrons jump directly to oxygen and form the superoxide anion, instead of moving through the normal series of well-controlled reactions of the electron transport chain. Peroxide is also produced from the oxidation of reduced flavoproteins, such as complex I. However, although these enzymes can produce oxidants, the relative importance of the electron transfer chain to other processes that generate peroxide is unclear. In plants, algae, and cyanobacteria, ROS are also produced during photosynthesis, particularly under conditions of high light intensity. This effect is partly offset by the involvement of carotenoids in photoinhibition, and in algae and cyanobacteria, by large amounts of iodide and selenium, which involves these antioxidants reacting with over-reduced forms of the photosynthetic reaction centres to prevent the production of ROS.
== Veterinary use == Ivermectin is routinely used to control parasitic worms in the gastrointestinal tract of ruminant animals. These parasites normally enter the animal when it is grazing, pass the bowel, and set and mature in the intestines, after which they produce eggs that leave the animal via its droppings and can infest new pastures. Ivermectin is only effective in killing some of these parasites, because of an increase in anthelmintic resistance. This resistance has arisen from the persistent use of the same anthelmintic drugs for the past 40 years. Resistance to ivermectin has also been reported in cattle tick (Rhipicephalus microplus) populations from the Brazilian Amazon, including resistant populations identified in western Pará. Additionally, the use of Ivermectin for livestock has a profound impact on dung beetles, such as T. lusitanicus, as it can lead to acute toxicity within these insects. In dogs, ivermectin is routinely used as prophylaxis against heartworm. Dogs with defects in the P-glycoprotein gene (MDR1), often collie-like herding dogs, can be severely poisoned by ivermectin. The mnemonic "white feet, don't treat" refers to Scotch collies that are vulnerable to ivermectin. Some other dog breeds (especially the Rough Collie, the Smooth Collie, the Shetland Sheepdog, and the Australian Shepherd), also have a high incidence of mutation within the MDR1 gene (coding for P-glycoprotein) and are sensitive to the toxic effects of ivermectin. For dogs, the insecticide spinosad may have the effect of increasing the toxicity of ivermectin.
=== Aortic and mitral valve disorders === Aortic and mitral valve disorders are left heart diseases that are more prevalent than diseases of the pulmonary or tricuspid valve in the right heart due to the higher pressures in the left heart. Stenosis of the aortic valve is characterized by a thickening of the valvular annulus or leaflets that limits the ability of blood to be ejected from the left ventricle into the aorta. Stenosis is typically the result of valvular calcification but may be the result of a congenitally malformed bicuspid aortic valve. This defect is characterized by the presence of only two valve leaflets. It may occur in isolation or in concert with other cardiac anomalies. Aortic insufficiency, or regurgitation, is characterized by an inability of the valve leaflets to appropriately close at the end systole, thus allowing blood to flow inappropriately backward into the left ventricle. Causes of aortic insufficiency in the majority of cases are unknown, or idiopathic. It may be the result of connective tissue or immune disorders, such as Marfan syndrome or systemic lupus erythematosus, respectively. Processes that lead to aortic insufficiency usually involve dilation of the valve annulus, thus displacing the valve leaflets, which are anchored in the annulus. Mitral stenosis is caused largely by rheumatic heart disease, though is rarely the result of calcification. In some cases, vegetations form on the mitral leaflets as a result of endocarditis, an inflammation of the heart tissue.
Sources: en.wikipedia.org
Jorgensen and Krynn DeArman Lukacs, who first demonstrated the capabilities of this technique. Capillary electrophoresis was first combined with mass spectrometry by Richard D. Smith and coworkers, and provides extremely high sensitivity for the analysis of very small sample sizes. Despite the very small sample sizes (typically only a few nanoliters of liquid are introduced into the capillary), high sensitivity and sharp peaks are achieved in part due to injection strategies that result in a concentration of analytes into a narrow zone near the inlet of the capillary. This is achieved in either pressure or electrokinetic injections simply by suspending the sample in a buffer of lower conductivity (e.g. lower salt concentration) than the running buffer. A process called field-amplified sample stacking (a form of isotachophoresis) results in concentration of analyte in a narrow zone at the boundary between the low-conductivity sample and the higher-conductivity running buffer. To achieve greater sample throughput, instruments with arrays of capillaries are used to analyze many samples simultaneously. Such capillary array electrophoresis (CAE) instruments with 16 or 96 capillaries are used for medium- to high-throughput capillary DNA sequencing, and the inlet ends of the capillaries are arrayed spatially to accept samples directly from SBS-standard footprint 96-well plates.
The third and final season of the American psychological drama television series Euphoria, inspired by Ron Leshem's miniseries of the same name, premiered on HBO on April 12, 2026. Series creator Sam Levinson serves as showrunner for the season. The season centers on recovering addict young adult Rue Bennett navigating her faith while also being drawn into the illegal drug trade. Zendaya stars as Rue alongside an ensemble cast consisting of Hunter Schafer, Jacob Elordi, Sydney Sweeney, Alexa Demie, Maude Apatow, Eric Dane, Adewale Akinnuoye-Agbaje, Martha Kelly, Chloe Cherry, and Toby Wallace. In February 2022, Euphoria was renewed for a third season. Filming commenced in February 2025 and wrapped in November. The season consists of eight episodes and received mixed reviews from critics. At the 78th Primetime Emmy and Creative Arts Awards the season was nominated seven times with Zendaya receiving her third nomination for Outstanding Lead Actress in a Drama Series. On May 31, 2026, the same day that the final episode of the third season was released, HBO confirmed that the series had concluded after three seasons.
=== Mass-18 notation === Under some circumstances, the abundances of 13CH3D and 12CH2D2 isotopologues are only measured as a sum, which leads to the notation for isotopologues of mass-18 (i.e. 13CH3D and 12CH2D2):
Sources: en.wikipedia.org
==== Cell culture using droplet-based microfluidics ==== Droplet-based microfluidic systems provide an analytic platform that enables the isolation of single cells or groups of cells in droplets. This tool offers high-throughput for cell experiments since droplet-based microfluidic systems can generate thousands of samples (droplets) per second. Compared with cell culture in conventional microtiter plates, microdroplets from μL to pL volumes reduce the use of reagents and cells. Additionally, automated handling and continuous processing allow assays to be carried out more efficiently. The isolated environment in an encapsulated droplet helps analyze each individual cell population. High-throughput cell culture experiments, for example, testing the behavior of bacteria, finding rare cell types, directed evolution, and cell screening are suitable for using the droplet-based microfluidic techniques.
=== Chemical fingerprinting and breath analysis === The exhaled human breath contains a few thousand volatile organic compounds and is used in breath biopsy and is used in breath biopsy as a biomarker to test for diseases, such as lung cancer. One study has shown that "volatile organic compounds ... are mainly blood borne and therefore enable monitoring of different processes in the body." And it appears that VOC compounds in the body "may be either produced by metabolic processes or inhaled/absorbed from exogenous sources" such as environmental tobacco smoke. Chemical fingerprinting and breath analysis of volatile organic compounds has also been demonstrated with chemical sensor arrays, which utilize pattern recognition for detection of component volatile organics in complex mixtures such as breath gas.
== Dietary requirements and sources == The Dietary Reference Intake for tyrosine is usually estimated together with phenylalanine. It varies depending on an estimate method, however the ideal proportion of these two amino acids is considered to be 60:40 (phenylalanine:tyrosine) as a human body has such composition. Tyrosine, which can also be synthesized in the body from phenylalanine, is found in many high-protein food products such as meat, fish, cheese, cottage cheese, milk, yogurt, peanuts, almonds, pumpkin seeds, sesame seeds, soy protein and lima beans. For example, the white of an egg has about 250 mg per egg, while beef, lamb, pork, tuna, salmon, chicken, and turkey contain about 500–1000 mg per 3 ounces (85 g) portion.
== Van Deemter equation == The van Deemter equation relates height equivalent to a theoretical plate (HETP) of a chromatographic column to the various flow and kinetic parameters which cause peak broadening, as follows:
Sources: en.wikipedia.org
It is associated with the melanocortin receptor family, particularly subtypes found in the central nervous system. This interaction is separate from the adrenal pathway activated by full-length ACTH.
Peptidases degrade the compound within minutes in circulation. This short half-life is one reason nasal delivery is used, placing the substance close to the olfactory and trigeminal pathways.
No large multicenter trials have been published in English-language journals. The existing human evidence consists mainly of smaller studies conducted in Russia, which limits generalization.
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。