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 2025-09-16. 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.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
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.
| 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.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
=== Biochemistry === Several studies have suggested that vanillin can affect the performance of antibiotics in laboratory conditions. Vanillin–HCl staining can be used to visualize the localisation of tannins in cells.
=== Neurotransmitters === T3 may increase serotonin in the brain, in particular in the cerebral cortex, and down-regulate 5HT-2 receptors, based on studies in which T3 reversed learned helplessness in rats and physiological studies of the rat brain.
UK-414,495 is a drug developed by Pfizer for the treatment of female sexual arousal disorder. UK-414,495 acts as a potent, selective inhibitor of the enzyme neutral endopeptidase, which normally serves to break down the neuropeptide VIP. The consequent increase in VIP activity alters blood flow to the genital region leading to increased lubrication and muscle relaxation.
== Ductal cell plasticity == There is disagreement about the plasticity potential of ductal cells in the adult pancreas. In the embryonic pancreas, the endocrine and exocrine cells originate in the pancreatic ducts as progenitor cells. In adult ductal cells, there are observations that these cells take on the identity of progenitor cells when stressed. This proposes the idea that there might be a subgroup of ductal cells that have the ability to dedifferentiate and generate endocrine cells when there is an injury to the pancreas. Essentially, ductal cells function in retaining the adult pancreas β cell mass when injured. However, there is a possibility that this capability is limited to a subtype of ductal cells only, meaning this cannot be a main pathway for pancreas regeneration.
Sources: en.wikipedia.org
The bicyclic core of C10-epi-kedarcidin chromophore was prepared by the sequential application of three carbon-carbon bond forming reactions, as shown in the retrosynthetic schematic above. First, a Sonogashira coupling was carried out between a bromovinyl electrophile and alkynyl nucleophile; ring closure to give a cyclic triyne was then accomplished by Glaser coupling of two terminal alkynes. The 5,9-fused bicyclic core was established by in situ generation of a vinyllithium species that underwent transannular 5-exo-dig cyclization.
=== Formation of the first hypercycles === Eigen made several assumptions about conditions that led to the formation of the first hypercycles. Some of them were the consequence of the lack of knowledge about ribozymes, which were discovered a few years after the introduction of the hypercycle concept and negated Eigen's assumptions in the strict sense. The primary of them was that the formation of hypercycles had required the availability of both types of chains: nucleic acids forming a quasispecies population and proteins with enzymatic functions. Nowadays, taking into account the knowledge about ribozymes, it may be possible that a hypercycle's members were selected from the quasispecies population and the enzymatic function was performed by RNA. According to the hypercycle theory, the first primitive polymerase emerged precisely from this population. As a consequence, the catalysed replication could exceed the uncatalysed reactions, and the system could grow faster. However, this rapid growth was a threat to the emerging system, as the whole system could lose control over the relative amount of the RNAs with enzymatic function. The system required more reliable control of its constituents—for example, by incorporating the coupling of essential RNAs into a positive feedback loop. Without this feedback loop, the replicating system would be lost. These positive feedback loops formed the first hypercycles.
=== Micro DisplayPort === Micro DisplayPort would have targeted systems that need ultra-compact connectors, such as phones, tablets and ultra-portable notebook computers. This standard would have been physically smaller than the currently available Mini DisplayPort connectors. The standard was expected to be released by Q2 2014.
Ears and sinuses: There is a risk of stretched or burst eardrums, usually crushed inwards during descent but sometimes stretched outwards on ascent. The diver can use a variety of methods to let air into or out of the middle ears via the Eustachian tubes. Sometimes swallowing will open the Eustachian tubes and equalise the ears. Lungs: There is a risk of pneumothorax, arterial gas embolism, and mediastinal and subcutaneous emphysema during ascent, which are commonly called burst lung or lung overpressure injury by divers. To equalise the lungs, all that is necessary is not to hold the breath during ascent. This risk does not occur when breath-hold diving from the surface, unless the diver breathes from an ambient pressure gas source underwater; breath-hold divers do suffer squeezed lungs on descent, crushing in the chest cavity, but, while uncomfortable, this rarely causes lung injury and returns to normal at the surface. Some people have pathology of the lung which prevent rapid flow of excess air through the passages, which can lead to lung barotrauma even if the breath is not held during rapid depressurisation. These people should not dive as the risk is unacceptably high. Most commercial or military diving medical examinations will look specifically for signs of this pathology. Diving mask squeeze enclosing the eyes and nose: The main risk is rupture of the capillaries of the eyes and facial skin because of the negative pressure difference between the gas space and blood pressure, or orbital emphysema from higher pressures.
== Composition == Guinness stout is made from water, malted barley, roasted barley, hops, and brewer's yeast. A portion of the barley is roasted to give Guinness its dark colour and characteristic taste. It is pasteurised and filtered. Until the late 1950s, Guinness was still racked into wooden casks. In the late 1950s and early 1960s, Guinness ceased brewing cask-conditioned beers and developed a keg brewing system with aluminium kegs replacing the wooden casks; these were nicknamed "iron lungs". Until 2016 the production of Guinness, as with many beers, involved the use of isinglass made from fish. Isinglass was used as a fining agent for settling out suspended matter in the vat. The isinglass was retained in the floor of the vat but it was possible that minute quantities might be carried over into the beer. Diageo announced in February 2018 that the use of isinglass in draught Guinness was to be discontinued and an alternative clarification agent would be used instead, making the drink acceptable to vegans and vegetarians.
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.