MC4 receptor is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-05-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid from research suppliers |
| Solubility | Freely soluble in water | Also dissolves in aqueous buffers; solutions are used fresh |
| Typical storage temperature | -20 °C for lyophilized powder | Short-term transport at 2-8 °C is common |
| Common analytical method | Reverse-phase HPLC | Paired with mass spectrometry for identity confirmation |
| Common synonyms | ACTH(4-10) analogue; MEHFPGP | N-terminal methionine retained in the chain |
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
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。
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。
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。
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。
=== September === September 1 Texas implements the "Heartbeat Act" banning abortions after six weeks of pregnancy. Texas residents are allowed to carry handguns without a license or training. Aftermath of the January 6 United States Capitol attack: The Department of Justice secures its 50th guilty plea in its criminal investigation of the January 6 riot at the Capitol. A state of emergency is declared in New York City after record rainfall and flash flooding shuts down much of the city's transportation system, caused by Tropical Storm Ida. September 2 Hurricane Ida More than 54 deaths are reported in New York and the wider northeastern United States amid the ongoing flood emergency, as rescuers continue to search for stranded people. The Vine Street Expressway in Philadelphia is closed due to massive flooding on portions of the highway. The Park Towne Place residential complex is also evacuated due to flooding. September 3 Jake Angeli, the so-called "QAnon Shaman" pleads guilty to obstructing a proceeding of Congress during the January 6 attack. Texas Heartbeat Act: Texas state judge Guerra Gamble blocks the Texas Right To Life from suing Planned Parenthood under the pretext of the abortion law. September 8 – The Robert E. Lee Monument on Monument Avenue in Richmond, Virginia, a statue of Confederate General Robert E. Lee, is removed. September 9 COVID-19 vaccination in the United States: President Biden issues new federal vaccine requirements affecting up to 100 million Americans.
== Historical aspects == Most natural polymers employed at early stages of human society are of condensation type. The synthesis of first truly synthetic polymeric material, bakelite, was announced by Leo Baekeland in 1907, through a typical step-growth polymerization fashion of phenol and formaldehyde. The pioneer of synthetic polymer science, Wallace Carothers, developed a new means of making polyesters through step-growth polymerization in 1930s as a research group leader at DuPont. It was the first reaction designed and carried out with the specific purpose of creating high-molecular-weight polymer molecules, as well as the first polymerization reaction whose results had been predicted by scientific theory. Carothers developed a series of mathematical equations to describe the behavior of step-growth polymerization systems which are still known as the Carothers equations today. Collaborating with Paul Flory, a physical chemist, they developed theories that describe more mathematical aspects of step-growth polymerization including kinetics, stoichiometry, molecular-weight distribution, etc. Carothers is also well-known for his invention of Nylon.
Brown (1912–2004), American chemist known for work on organoboranes, 1979 Nobel Prize in Chemistry Jeannette Brown (born 1934), American organic medicinal chemist, historian, and author, known for research on drug development targeting tuberculosis and coccidiosis Jeanette Grasselli Brown (1928–2025), American analytical chemist and spectroscopist Rachel Fuller Brown (1898–1980), American chemist who co-developed the first useful antifungal antibiotic, nystatin
Sources: en.wikipedia.org
=== 19th century === Apparently unaware of Smeaton's work, the same principle was identified by Frenchman Louis Vicat in the first decade of the nineteenth century. Vicat went on to devise a method of combining chalk and clay into an intimate mixture, and, burning this, produced an "artificial cement" in 1817 considered the "principal forerunner" of Portland cement and "...Edgar Dobbs of Southwark patented a cement of this kind in 1811." In Russia, Egor Cheliev created a new binder by mixing lime and clay. His results were published in 1822 in his book A Treatise on the Art to Prepare a Good Mortar published in St. Petersburg. A few years later in 1825, he published another book, which described various methods of making cement and concrete, and the benefits of cement in the construction of buildings and embankments.
== Overdose == In the event of arsenic poisoning (manifesting as seizures, muscle weakness, confusion), the administration of the drug should be immediately discontinued, and appropriate treatment should be initiated. Penicillamine is commonly used at a dose of up to 1 g/day. For patients unable to take oral medications, dimercaprol can be administered intramuscularly at a dose of 3 mg/kg body weight every 4 hours until life-threatening symptoms subside. In cases of coagulopathy, DMSA is recommended at a dose of 10 mg/kg body weight every 8 hours for 5 days, followed by every 12 hours for 2 weeks. Kidney dialysis may also be considered.
== Adverse effects == Cefodizime has been shown to be generally well tolerated in drug trials and its adverse effects are mainly gastrointestinal or dermatological. Gastrointestinal adverse effects were observed in 2.4% of patients during clinical trials and included: diarrhea, nausea, vomiting, and elevated transaminases. Allergic symptoms were observed in 1.1% of patients and include: exanthema, urticaria, and pruritus. Other adverse effects observed include local site reactions, pain at site of injection, and phlebitis.
In April 1943, Enrico Fermi suggested to Robert Oppenheimer the possibility of using the radioactive byproducts from enrichment to contaminate the German food supply. The background was fear that the German atomic bomb project was already at an advanced stage, and Fermi was also skeptical at the time that an atomic bomb could be developed quickly enough. Oppenheimer discussed the proposal with Edward Teller, who suggested the use of 90Sr. James Bryant Conant and Leslie R. Groves were also briefed, but Oppenheimer wanted to proceed with the plan only if enough food could be contaminated with the weapon to kill half a million people.
Sources: en.wikipedia.org
Through most of the European winter months it was based in Antwerp. In late March 1945 the Rhodesian fighters formed part of the force tasked with protecting the descending Allied paratroopers during Field-Marshal Montgomery's crossing of the Rhine. During April the squadron operated over Hanover and the northern Netherlands. No. 44 Squadron, meanwhile, embarked on bombing raids on targets as far away as Gdynia and Königsberg in East Prussia, as well as towns and cities closer to Berlin such as Dresden, Emden and Leipzig. Its last bombing operation was a raid on the Berghof, Hitler's residence, near Berchtesgaden in Bavaria on 25 April 1945. After Germany surrendered on 7 May, ending the war in Europe, No. 44 Squadron was one of many units selected to evacuate British prisoners of war home from the continent.
=== Khartoum massacre === In early June 2019, following al-Burhan's and Hemedti's visits to the Egyptian, UAE and Saudi leaders, the Sudanese Security Forces and Rapid Support Forces, including Janjaweed militias, led by al-Burhan and his deputy cracked down on peaceful protests in Sudan, starting with the 3 June Khartoum massacre. Human rights groups said that peaceful protesters were killed and about forty of the bodies were thrown in the river Nile, hundreds were tortured, violated and raped in the streets of Khartoum. Al-Burhan's talks with the opposition on forming a combined government were then cancelled. During the days that followed, the TMC arrested several of the opposition leaders. Iyad el-Baghdadi interpreted the decision-making by the TMC under al-Burhan's leadership as being strongly influenced by the general context of the Saudi, UAE and Egyptian leaders being afraid of democratic movements. Mahmoud Elmutasim, a political activist and doctor who graduated from the University of Khartoum, similarly stated that Saudi Arabia and the UAE are opposed to the existence of democracies in the Middle East, since if "the idea of democracy itself [should] ever take root, or become widespread in the Middle East," then it would constitute a threat to the governmental systems of Saudi Arabia and the UAE.
Pfizer has hired customs and narcotics experts worldwide to track down fakes and assemble evidence that can be used to pursue civil suits for trademark infringement. In July 2008, Pfizer announced 275 job cuts at its manufacturing facility in Portage, Michigan. Portage was previously the world headquarters of Upjohn Company, which had been acquired as part of Pharmacia.
Sources: en.wikipedia.org
It consists mainly of animal experiments and small clinical reports, with much of the clinical material published in Russian-language journals. Large independent trials are scarce. Separating reliable effects from chance findings is consequently difficult.
A fraction of an intranasal dose is thought to reach the central nervous system, and this route is favoured partly for that reason. The proportion is not well characterized. Direct measurement in humans remains difficult with current methods.
Raised BDNF and NGF expression has been reported across several animal studies, which makes the signal fairly consistent. Whether the same change occurs in humans at usable doses is not established. It is best treated as a working hypothesis rather than a confirmed clinical mechanism.
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.