This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-28 and is reviewed periodically as new material appears.
Claims about enhanced focus, memory, or mood in healthy people rest mostly on anecdotal reports and community discussion rather than on controlled data. It remains unclear whether any cognitive benefit observed in patients recovering from brain injury would extend to uninjured users. Dose-response relationships, long-term safety, and interactions with other drugs are not well characterized in the peer-reviewed literature. Questions about optimal route of administration and treatment duration likewise remain open.
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.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
| 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 |
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.
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.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
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.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
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.
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==== Pressure on the legal profession ==== A group of 90 lawyers from Hebei, Henan and Shandong—the three worst affected provinces—had made pro bono offers to assist victims, and a list of their names was published. Organisers of the group declared that they had come under pressure from officials to not get involved in the issue. The Beijing Lawyers' Association, a part of the Communist Party apparatus, asked its members "to put faith in the party and government". Other members of the group have reportedly received less subtle requests. Authorities are said to fear social unrest if lawsuits were unleashed. Pro-Beijing Hong Kong journal Ta Kung Pao reported that central authorities, fearful of the effect of mass lawsuits, held a meeting with lawyers' groups on 14 September, asking them to "act together, and help maintain stability". Chang Boyang, one of the group of volunteer lawyers, said he had filed one suit in Guangdong against Sanlu on behalf of the parents of one victim, and another suit in Henan. According to Chang, the justice department of Henan ordered 14 Henan lawyers to drop their cases and "follow the arrangements set out by the government". He said they were told that if they did not, "the lawyer and the firm will be dealt with." Zhang Yuanxin, lawyer and officer in the Xinjiang Lawyers' Association said that these government actions have "set back the development of the legal profession," and called this interference in citizen lawsuits "intolerable".
Sources: en.wikipedia.org
=== Triacidic bases === When one molecule of base via complete ionization produces three hydroxide ions, the base is said to be triacidic or triprotic. Examples of triacidic bases are: Aluminium hydroxide, ferric hydroxide, gold(III) hydroxide.
The project was originally estimated to cost $21.6 million and was to be the largest expansion project in the main branch's history; it entailed building 84 miles (135 km) of stacks, which could hold 3.2 million books. Construction on the stacks started after the park was closed. The park was excavated and the Great Lawn was rebuilt above it. Once the underground facilities were completed, Bryant Park was completely rebuilt, with 2.5 to 6 feet (0.76 to 1.83 m) of earth between the park surface and the storage facility's ceiling.
Spectroscopy with a variable pathlength cell takes advantage of Beer–Lambert law to determine concentrations of various solutions. By knowing the molar absorptivity of the material and varying the path length, absorption can be plotted as a function of path length. See sample plot to the right: By taking a linear regression of the linear plot above an expression relating Absorbance, A, slope, m, pathlength and concentration can be derived. A linear equation of two variables can be derived,
Sources: en.wikipedia.org
=== Dilution to threshold === A dilution series of a sample or extract is prepared and assessed for presence of odour. The result can be described as the odour potency of a compound. One kind of analysis is to measure the maximum dilution in the series in which odour is still perceived. The resulting value is called the flavour dilution (FD) factor in the aroma extraction dilution analysis (AEDA) developed in 1987 by Schieberle and Grosch. On the other hand, another kind of analysis is to also measure the duration of the perceived odour to compute peak areas. The peak areas are known as Charm values in the CharmAnalysis developed in 1984 by Acree and co-workers. The former can then be interpreted as the peak height of the latter. Because the odour threshold of a compound is intended to be measured from a prepared series of dilution (commonly by a factor of 2–3 with 8–10 dilutions), the precision and variation in data can be determined from the dilution factors used. Due to time demand requirements from this method and the general requirement for multiple assessors to minimise errors, having the column split into multiple odour ports would be beneficial for the method.
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The three substrates of this enzyme are formaldehyde, oxidised nicotinamide adenine dinucleotide (NAD+), and water. Its products are formic acid, reduced NADH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is formaldehyde:NAD+ oxidoreductase. Other names in common use include NAD+-linked formaldehyde dehydrogenase, s-nitrosoglutathione reductase (GSNO reductase) and NAD+-dependent formaldehyde dehydrogenase. This enzyme participates in methane metabolism.
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.
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.