This is a working overview of ACTH fragment, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analogue of the ACTH(4-10) fragment |
| Amino acid sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Single-letter form MEHFPGP |
| Molecular formula | C37H51N9O10S | Free peptide, nominal mass near 814 Da |
| First registration | 1994, Russia | Nasal formulation for neurological indications |
| Typical purity grade | 95% or higher by HPLC | Research material; higher grades used as reference standards |
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.
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.
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.
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.
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.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
=== Studies in vitro === Epitalon appears to induce telomere elongation via increased telomerase activity in human somatic cells in vitro, based on a study in human fibroblast cell cultures. Elongation of telomeres by epitalon was sufficient to surpass the Hayflick limit in a cell culture of human fetal fibroblast cells, extending their proliferative potential from termination at the 34th passage in the control cell population to beyond the 44th passage in the treated cell population, while increasing the lengths of their telomeres to levels comparable to those of cells in the original culture. Epitalon induces decondensation of heterochromatin near the centromeres in cultured lymphocytes originating from samples taken from humans of ages 76 to 80 years. Epitalon appears to inhibit the synthesis of the MMP9 protein in vitro in aging skin fibroblasts.
In the case of the simians, the loss of the ability to make vitamin C may have occurred much farther back in evolutionary history than the emergence of humans or even apes, since it evidently occurred soon after the appearance of the first primates, yet sometime after the split of early primates into the two major suborders Haplorrhini (which cannot make vitamin C) and its sister suborder of non-tarsier prosimians, the Strepsirrhini ("wet-nosed" primates), which retained the ability to make vitamin C. According to molecular clock dating, these two suborder primate branches parted ways about 63 to 60 million years ago. Approximately three to five million years later (58 million years ago), only a short time afterward from an evolutionary perspective, the infraorder Tarsiiformes, whose only remaining family is that of the tarsier (Tarsiidae), branched off from the other haplorrhines. Since tarsiers also cannot make vitamin C, this implies the mutation had already occurred, placing it between these two marker points (63 to 58 million years ago). It has also been noted that the loss of the ability to synthesize ascorbate strikingly parallels the inability to break down uric acid, also a characteristic of primates. Uric acid and ascorbate are both strong reducing agents. This has led to the suggestion that, in higher primates, uric acid has taken over some of the functions of ascorbate.
Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychiatric conditions. SSRIs primarily work by blocking serotonin reabsorption (reuptake) via the serotonin transporter, leading to gradual changes in brain signaling and receptor regulation, with some also interacting with sigma-1 receptors, particularly fluvoxamine, which may contribute to cognitive effects. Marketed SSRIs include six main antidepressants—citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline—and dapoxetine, which is indicated for premature ejaculation. Fluoxetine has been approved for veterinary use in the treatment of canine separation anxiety. SSRIs are the most widely prescribed antidepressants in many countries. In adults, they are recommended as a first-line treatment for moderate to severe depression, while for mild depression non-drug treatments are preferred unless the patient chooses medication. A 2018 meta analysis of 21 antidepressants showed that all antidepressants (including SSRIs) were more effective than placebo in adults with major depressive disorder.
== January 8, 1982 (Friday) == To end a federal antitrust suit that had been brought in 1974 by the U.S. Department of Justice, the telephone monopoly American Telephone & Telegraph (AT&T) agreed to sell its 22 individual Bell System companies that had controlled most U.S. telephone lines. On the same day, the Department of Justice dropped its 12-year-old antitrust suit against International Business Machines (IBM), ending a trial that had started on May 19, 1975. The Umkhonto we Sizwe paramilitary force of South Africa's anti-apartheid African National Congress, carried out an attack on the construction site of the Koeberg Nuclear Power Station, planned to be the white South African government's first nuclear power plant, causing 500 million rands worth of damage and setting back the completion date by 18 months. The first White House meeting concerning Project Excalibur, the proposed Strategic Defense Initiative (nicknamed the "Star Wars defense") for the United States against an enemy missile attack, took place as Edward Teller, Karl Bendetsen, William Wilson and Joseph Coors made a one-hour presentation to U.S. President Ronald Reagan for a satellite with lasers that could destroy nuclear missiles after their launch.
Lee Hsien Loong's tenure included the 2008 financial crisis, the resolution of a dispute over land ownership at Tanjong Pagar railway station between Singapore and Malaysia, the introduction of the two integrated resorts (IRs) located at the Marina Bay Sands and Resorts World Sentosa as well as the COVID-19 pandemic. The PAP experienced its worst electoral performance in 2011, securing only 60% of the vote. While this would be considered a landslide victory in many countries since it preserved the party's supermajority, it was regarded locally as a poor outcome, reflecting public debate over issues such as the high rates of immigration and the rising cost of living. On 23 March 2015, Lee Kuan Yew died, and a one-week period of public mourning was observed nationwide. Subsequently, the PAP regained its dominance in Parliament through the September general election, receiving 69.9% of the popular vote, although this remained lower than the 2001 tally of 75.3% and the 1968 tally of 86.7%. The 2020 election held in July during COVID saw the PAP drop to 61% of the vote, while the Workers' Party (WP) took 10 of the 93 seats, including its leader Pritam Singh becoming the first de jure leader of the opposition since independence. On 15 May 2024, Lawrence Wong became Singapore's fourth prime minister and the first born after independence. Wong's first electoral test came at the 2025 election, which saw the PAP winning 65.5% of the vote and 87 out of 97 seats in Parliament; the WP retained their 10 seats.
Sources: en.wikipedia.org
The gastrointestinal tract has a form of general histology with some differences that reflect the specialization in functional anatomy. The GI tract can be divided into four concentric layers in the following order:
== Medically significant species == Mortality (often determined by measured toxicity on mice) is a commonly used indicator of the danger of any given venomous snake, but important too are efficiency of venom delivery, venom yield, and behavior upon encountering humans. Given these additional, practical concerns, many snake experts have cited the black mamba and the coastal taipan as the world's most dangerous snakes – even though their venoms, drop for drop, are not the most lethal. Both species are elapids, and in several aspects of morphology, ecology and behavior, the coastal taipan is strongly convergent with the black mamba.
The Parliament of Trinidad and Tobago is the legislative branch of the government of Trinidad and Tobago. The Parliament is bicameral. It consists of the elected House of Representatives, which has 41 members elected for a five-year term in single-seat constituencies, and the Senate which has 31 members appointed by the president: 16 government senators appointed on the advice of the prime minister, 6 opposition senators appointed on the advice of the leader of the opposition and 9 independent senators appointed by the president to represent other sectors of civil society.
== Pharmacokinetics == As R7 is a slightly larger molecule than tropoflavin, 72.5 mg R7 is molecularly equivalent to 50 mg tropoflavin. Relative to a roughly molecularly equivalent dose of tropoflavin, the area-under-curve levels of R7 were found to be 7.2-fold higher upon oral administration to mice, and R7 hence has a greatly improved oral bioavailability in mice of approximately 35%. Moreover, whereas tropoflavin itself is mostly metabolized in mice within 30 minutes, tropoflavin as a metabolite was still detectable in plasma at 8 hours after administration with R7, indicating that R7 sustainably releases tropoflavin into circulation. In accordance, the terminal half-life of R7 is about 195 minutes (3.25 hours) in mice. The Tmax of R7 is about 60 minutes in mice, and its Cmax for a 78 mg/kg dose was 262 ng/mL, whereas that for a 50 mg/kg dose of tropoflavin was 70 ng/mL.
Sources: en.wikipedia.org
Registered medical products are most often 0.1% nasal drops. Research suppliers ship lyophilized powder, usually in milligram quantities, which is dissolved before use. The active peptide is the same in both cases; presentation and excipients differ.
No. The peptide is synthetic, although it is modelled on a fragment of a naturally occurring hormone. ACTH(4-10) is generated when ACTH is cleaved, but the Pro-Gly-Pro extension is not a known endogenous sequence. It is therefore a designed analogue rather than a natural metabolite.
The label reflects reported effects on attention, memory and recovery after neurological injury in regional clinical reports. Those reports are mostly small and have not been widely replicated outside the region. The classification is descriptive and does not imply a single defined mechanism.
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。