The short version of ACTH analog fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Analog of an ACTH fragment |
| Amino acid length | Seven residues | Met-Glu-His-Phe-Pro-Gly-Pro |
| Origin | Moscow, 1980s | Institute of Molecular Genetics |
| Approved regions | Russia and some neighboring states | Not cleared in Western markets |
| Common trade names | Multiple national brands | Sold as a nasal formulation |
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.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
Semax 是一种人工合成的七肽，氨基酸序列为 Met-Glu-His-Phe-Pro-Gly-Pro，单字母缩写记作 MEHFPGP。它被归类为促肾上腺皮质激素片段 ACTH(4-10) 的结构类似物，但并不天然存在于生物体内。母体片段 ACTH(4-10) 的序列为 Met-Glu-His-Phe-Arg-Trp-Gly，Semax 替换了中间两个残基，并在羧基端延长了 Pro-Gly-Pro 三肽。这种延长被普遍认为能提升分子对肽酶的耐受性。
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
研究兴趣主要集中在神经营养因子相关的路径上，包括脑源性神经营养因子与神经生长因子的表达变化。部分实验报告称在特定条件下观察到这些因子的水平上升，但具体信号通路和剂量依赖关系仍未完全厘清。多数公开数据来自细胞模型和动物实验，人体对照研究数量有限。因此，该化合物的作用机制在文献中属于活跃讨论，而非已经确立的定论。
=== Accelerator mass spectrometry === HVEC tandems enabled accelerator mass spectrometry (AMS), a technique that transformed radiocarbon dating and created new applications across multiple fields. In May 1977, researchers at the University of Rochester used an HVEC MP tandem to demonstrate that carbon-14 atoms could be detected directly in milligram-scale samples—compared to the 10–100 grams required by conventional decay counting. The tandem configuration exploited a key property: nitrogen-14, the primary interference in conventional dating, forms no stable negative ions and cannot survive acceleration through the system, eliminating a major source of contamination. The reduction in sample size made radiocarbon dating applicable to precious artifacts and specimens where destructive sampling had been prohibitive. Tandem machines also extended the practical range of radiocarbon dating from approximately 40,000 to potentially 100,000 years. Beyond radiocarbon applications, AMS expanded into hydrology, geoscience, biomedicine, archaeology, and paleoclimatology.
CTCCAACATCAAGGAAGATGGCATTTCTAG (sequence source: US FDA ETEPLIRSEN BRIEFING DOCUMENT NDA 206488), 30-mer, 20% G, 43% CG, Predicted Tm: 88.9 °C at 10 μM oligo. Oligo complement CTAGAAATGCCATCTTCCTTGATGTTGGAG DMD-001 Exon 51, ENST00000357033.8 in Ensembl.org, RNA target site marked. Given that the target site is within an exon, this is likely blocking binding of an exonic splice enhancer protein and so altering splicing by interfering with splice regulation. CTCCTACTCAGACTGTTACTCTGGTGACACAACCTGTGGTTACTAAGGAAACTGCCATCT CCAAA[CTAGAAATGCCATCTTCCTTGATGTTGGAG]GTACCTGCTCTGGCAGATTTCAACC GGGCTTGGACAGAACTTACCGACTGGCTTTCTCTGCTTGATCAAGTTATAAAATCACAGA GGGTGATGGTGGGTGACCTTGAGGATATCAACGAGATGATCATCAAGCAGAAG
=== 2009: Norovirus outbreak === On 27 February 2009, Blumenthal closed the Fat Duck temporarily after a number of customers reported feeling unwell at different times. On 6 March, it was reported that 400 people had stated they had felt unwell after eating at the restaurant. The cause was later given by the Health Protection Agency as norovirus, thought to have originated from oysters harvested from beds contaminated with sewage. The virus spread further after being contracted by staff members. The Fat Duck was criticised for its cleaning methods and its slow response, and received 529 complaints of illness. It was the largest norovirus outbreak ever documented at a restaurant. The Fat Duck reopened on 12 March 2009.
Sources: en.wikipedia.org
Many structures of water-soluble domains of ABC proteins have been produced in recent years. ATP-binding domain of ABC transporters Bacterial binding protein-dependent transporter Transmembrane domain of ABC transporters Elizabeth P. Carpenter, British structural biologist, first to describe structure of human ABC-transporter ABC10 Classification of ABC transporters in TCDB ABCdb Archaeal and Bacterial ABC Systems database, ABCdb ATP-Binding+cassette+transporters at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
== Thallium-201 == Thallium-201 (201Tl) is a synthetic radioisotope of thallium. It has a half-life of 3.0421 days and decays by electron capture, emitting photons consisting mainly of K X-rays (~70–80 keV), and gammas of 135 and 167 keV (the latter stronger, emitted in 10% of decays). Thallium-201 is synthesized by the neutron activation of stable thallium in a nuclear reactor, or by the 203Tl(p, 3n)201Pb nuclear reaction in cyclotrons, as 201Pb then decays to 201Tl. It is a radiopharmaceutical, as it has fair imaging characteristics without excessive patient radiation dose. It was the most popular isotope used for nuclear cardiac stress tests. This nuclide has largely been replaced by technetium-99m, which has a shorter half-life (6 hours instead of 3 days) and a single high-energy photon peak (140 keV), which is better for imaging than the 3 energy peaks of thallium-201. Thallium-201 is now mostly used for myocardial viability studies. It will redistribute in body tissues, whereas Tc will not; Tl is taken up by the cardiac muscle via Na+/K+ pumps. Delayed imaging will show uptake in damaged but still living myocardial cells, which would appear as a scar with Tc or 82Rb.
=== Voltage limits === Lithium-ion cells are susceptible to stress by voltage ranges outside of safe ones between 2.5 and 3.65/4.1/4.2 or 4.35 V (depending on the components of the cell). Exceeding this voltage range results in premature aging and in safety risks due to the reactive components in the cells. When stored for long periods the small current draw of the protection circuitry may drain the battery below its shutoff voltage; normal chargers may then be useless since the battery management system (BMS) may retain a record of this battery (or charger) "failure". Many types of lithium-ion cells cannot be charged safely below 0 °C, as this can result in plating of lithium on the anode of the cell, which may cause complications such as internal short-circuit paths. Other safety features are required in each cell:
Sources: en.wikipedia.org
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.
It is registered as a medicine in Russia and has been used clinically there for decades. No regulatory agency in Western Europe or North America has approved it for any indication.
Semax corresponds to the four-to-ten fragment of adrenocorticotropic hormone. Because it omits the first three residues, it lacks the adrenal-stimulating action of the full hormone.
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.