The short version of heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-31. Anything still debated is marked as such rather than presented as settled.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Contains one methionine sulfur atom |
| Molecular mass | Approximately 814 Da | Consistent with a seven-residue peptide |
| Appearance | White to off-white powder | Typical lyophilized form |
| Solubility | Freely soluble in water | Also soluble in dimethyl sulfoxide |
| Typical storage | -20 °C, desiccated | Limits methionine oxidation |
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.
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
== See also == Substituted cathinone 3-Chloro-N-cyclopropylcathinone (3Cl-CpC; PAL-433, RTI-6037-39) 3-Fluoromethcathinone 3-Bromomethcathinone 3-Fluoromethamphetamine 3-Methylmethcathinone 3-Chloromethamphetamine 4-Chloromethcathinone 5-Cl-bk-MPA
=== Electrochemical sensing === Magneto-electrochemical assays are based on the use of magnetic nanoparticles in electrochemical sensing either by being distributed through a sample where they can collect and preconcentrate the analyte and handled by a magnetic field or by modifying an electrode surface enhancing its conductivity and the affinity with the analyte. Coated-magnetic nanoparticles have a key aspect in electrochemical sensing not only because it facilitates the collecting of analyte but also it allows MNPs to be part of the sensor transduction mechanism. For the manipulation of MNPs in electrochemical sensing has been used magnetic electrode shafts or disposable screen-printed electrodes integrating permanent bonded magnets, aiming to replace magnetic supports or any external magnetic field.
=== Pharmacokinetics === The conversion of codeine to morphine occurs in the liver and is catalyzed by the cytochrome P450 enzyme CYP2D6. CYP3A4 produces norcodeine, and UGT2B7 conjugates codeine, norcodeine, and morphine to the corresponding 3- and 6-glucuronides. Srinivasan, Wielbo, and Tebbett speculate that codeine-6-glucuronide is responsible for a large percentage of the analgesia of codeine, and thus these patients should experience some analgesia. CYP2D6 converts codeine into morphine, which then undergoes glucuronidation. Life-threatening intoxication, including respiratory depression requiring intubation, can develop over a matter of days in patients who have multiple functional alleles of CYP2D6, resulting in ultrarapid metabolism of opioids such as codeine into morphine. Studies on codeine's analgesic effect are consistent with the idea that metabolism by CYP2D6 to morphine is important, but some studies show no major differences between those who are poor metabolizers and extensive metabolizers. Evidence supporting the hypothesis that ultrarapid metabolizers may get greater analgesia from codeine due to increased morphine formation is limited to case reports. Due to the increased metabolism of codeine to morphine, ultrarapid metabolizers (those possessing more than two functional copies of the CYP2D6 allele) are at increased risk of adverse drug effects related to morphine toxicity.
The compound is now under active investigation by researchers at NIMH for potential clinical use, and it is hoped that use of HNK instead will mitigate the various concerns (such as abuse and dissociation) of using ketamine itself in the treatment of depression.
Sources: en.wikipedia.org
Molecular oxygen is a good terminal electron acceptor because it is a strong oxidizing agent. The reduction of oxygen does involve potentially harmful intermediates. Although the transfer of four electrons and four protons reduces oxygen to water, which is harmless, transfer of one or two electrons produces superoxide or peroxide anions, which are dangerously reactive.
In January 1821, in expectation of the abolition in Spain of the Constitution of 1812, Iturbide was chosen and was sent by the officials of New Spain with Guerrero, the leader of the rebellions. He began so-called "peace" negotiations, suggesting the parties unite to establish an independent New Spain. Later, Iturbide was dethroned and quietly captured to be executed. The simple terms that Iturbide proposed became the basis of the Plan of Iguala: the independence of New Spain (now to be called the Mexican Empire) with Ferdinand VII or another Bourbon as emperor; the retention of the Catholic Church as the official state religion and the protection of its existing privileges; and the equality of all New Spaniards, whether immigrants or native-born. Many of that laws was abolished decades later or are in present-day Mexico. The following month the other important guerrilla leader, Guadalupe Victoria, joined the alliance, and on 1 March Iturbide was proclaimed head of a new Army of the Three Guarantees. The representative of the new Spanish government, Superior Political Chief Juan O'Donojú, who replaced the previous viceroys, arrived in Veracruz on 1 July 1821, but he found that royalists held the entire country except for Veracruz, Mexico City and Acapulco. Since at the time that O'Donojú had left Spain, the Cortes was considering greatly expanding the autonomy of the overseas Spanish possessions, O'Donojú proposed to negotiate a treaty with Iturbide on the terms of the Plan of Iguala.
The course of the disease varies greatly. Some people have mild short-term symptoms, but in most the disease is progressive for life. Around 25% will have subcutaneous nodules (known as rheumatoid nodules); this is associated with a poor prognosis.
=== In vivo anti-inflammatory activity === The cyclic peptide NR58-3.14.3 was shown to be a powerful anti-inflammatory agent in vivo, inhibiting inflammation in a number of disease models such as atherosclerosis, ischemia, lung disease, surgical adhesions, endometriosis and pulmonary graft-versus-host disease. It has been suggested that blockage of chemokine function using these molecules should not have a detrimental toxicological effect.
The 1578 death of King Sebastian in battle and the subsequent 1580 death of King Henry without a named heir, precipitated a succession crisis. Philip II of Spain, whose mother was Isabella of Portugal, was one of the candidates for the throne. In 1581 he was acclaimed king of Portugal, creating a personal union between the two kingdoms. This deprived Portugal of an independent foreign policy and led to the Dutch-Portuguese War. In 1641, John, Duke of Braganza, was proclaimed king by the Cortes after an uprising led by some nobles in the year before, ending the Iberian Union under the House of Habsburg, and beginning the rule of the House of Braganza. Following the Portuguese Restoration War, Spain recognised Afonso VI as king of Portugal. During the reign of John V, the large influx of Brazilian gold into the royal treasury, chiefly through the royal fifth, produced a resource curse that weakened industry and cereal production, created a gold rush from Portugal to Brazil, and led to prolonged economic stagnation, permanent reduction of income growth, and the interruption of the institutional and economic progress achieved in the 17th century. After the depletion of gold revenues, Portugal was left with a weak industrial base and backward institutional and educational structures. This condition was exacerbated by Sebastião José de Carvalho e Melo, 1st Marquis of Pombal, who emerged as the country's de facto ruler in the aftermath of the 1755 earthquake and tsunami, one of the kingdom's worst recorded natural disaster.
Sources: en.wikipedia.org
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.
Most published work uses intranasal administration, matching the route of the registered Russian formulation. Some animal experiments use intravenous or intraperitoneal injection. The route matters because the intact peptide is cleared rapidly from blood, so exposure differs between methods.
A purity value describes the share of the powder accounted for by the target peptide, usually by high-performance liquid chromatography. It does not confirm that the sequence is correct, which requires mass spectrometry or amino acid analysis. Purity and identity are separate checks.
It is a synthetic peptide of seven amino acids. Its backbone corresponds to a fragment of adrenocorticotropic hormone extended at the carboxyl end. The material is distributed as a lyophilized solid for laboratory use.