Everything below concerns Intranasal delivery. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-17. Numbers and descriptions here follow the published literature rather than marketing material.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Pseudothrombocytopenia (PTCP) or spurious thrombocytopenia is an in-vitro sampling problem which may mislead the diagnosis towards the more critical condition of thrombocytopenia. The phenomenon may occur when the anticoagulant used while testing the blood sample causes clumping of platelets which mimics a low platelet count. The phenomenon has first been reported in 1969.
== External links == RAGE+receptor at the U.S. National Library of Medicine Medical Subject Headings (MeSH) AGER on the Atlas of Genetics and Oncology Overview of all the structural information available in the PDB for UniProt: Q15109 (Human Advanced glycosylation end product-specific receptor) at the PDBe-KB. Overview of all the structural information available in the PDB for UniProt: Q62151 (Mouse Advanced glycosylation end product-specific receptor) at the PDBe-KB.
=== Sleep apnea === Sleep apnea is a condition characterized by repeated interruptions in breathing during sleep, significantly affecting the flow of blood through the brain's blood vessels. These interruptions cause intermittent hypoxia, leading to vascular changes such as the constriction of cerebral blood vessels, thereby impacting overall brain blood flow. Sleep apnea can also result in reduced blood flow in the ciliary artery area, contributing to the development of NAION through various mechanisms. The results of a retrospective study investigating high altitude (7,000-9,000 feet) as a potential risk factor for NAION suggested that high-altitude-associated NAION might be linked to undiagnosed obstructive sleep apnea. The study concluded that NAION could occur under high-altitude conditions, often in younger individuals with obstructive sleep apnea and "disc-at-risk". Each apnea episode typically causes temporary increases in blood pressure and heart rate, leading to fluctuations that can result in irregular blood flow to the brain. This may cause long-term changes in the structure and function of cerebral blood vessels. The brain's mechanism for maintaining constant blood flow despite changes in systemic blood pressure, known as cerebral autoregulation, can be impaired by sleep apnea. This impairment results in periods of both reduced and excessive cerebral blood flow. Repeated airway obstruction during sleep leads to intermittent hypoxia, causing oxidative stress and damaging endothelial cells of blood vessels, including those supplying the optic nerve head.
== Synthesis == Fumaric acid is produced based on catalytic isomerisation of maleic acid in aqueous solutions at low pH. It precipitates from the reaction solution. Maleic acid is accessible in large volumes as a hydrolysis product of maleic anhydride, produced by catalytic oxidation of benzene or butane.
Sources: en.wikipedia.org
=== Maximum depositional age === Some of the most important information we can get from detrital zircon ages is the maximum depositional age of the referring sedimentary unit. The sedimentary unit cannot be older than the youngest age of the analyzed detrital zircons because the zircon should have existed before the rock formation. This provides useful age information to rock strata where fossils are unavailable, such as the terrestrial successions during Precambrian or pre-Devonian times. Practically, maximum depositional age is averaged from a cluster of youngest age data or the peak in age probability because the youngest U-Pb age within a sample is almost always younger with uncertainty.
Euphorbia caducifolia is a subtropical succulent species of flowering plant in the spurge family Euphorbiaceae. It is found in the arid regions of northwestern Indian subcontinent. In India it is known as the leafless milk hedge.
Labour Party leader Sir Keir Starmer publishes details of his tax returns, a day after the prime minister. The Westminster Parliament announces that the TikTok app will be banned on "all parliamentary devices and the wider parliamentary network". The British Medical Association announces that junior doctors in England will stage a four-day strike from 11 to 15 April in their continued quest for a 35% pay rise. England footballer Harry Kane becomes the England national football team all-time leading goalscorer with 54 goals in a 2–1 win vs Italy national football team, surpassing the previous record of 53 goals held by Wayne Rooney, who broke the record back in September 2015. 24 March Charles III's state visit to France, his first official overseas visit as King, is postponed following a request by French president Emmanuel Macron after unions threatened to stage a day of protests over pension reforms during his visit. MPs vote to back the Protection from Sex-based Harassment in Public Bill, which will make catcalling, following someone or blocking their path an offence in England and Wales with a punishment of up to two years in prison. COVID-19 in the UK: The final Coronavirus Infections Survey is published by the Office for National Statistics, with data for the week up to 13 March. It shows an increase in COVID-19 cases for England, but an uncertain picture for the rest of the UK.
Sources: en.wikipedia.org
=== Detection === A procedure of retrospective detection of Novichok type poisons in victim's tissues was proposed in 2021-2. This method is a modification of the procedure that was developed earlier for identification of sarin poisoning. This method capitalizes on the fact that poisoning by organic phosphonates occurs via phosphonylation of the hydroxy group of serine in the active site of cholinesterases, and that severe poisoning occurs when a major part of these enzymes are inactivated. The concentration of butyryl cholinesterase (HuBuChE) in human plasma is normally about 80 nM. That makes it a good source of adducts that can be subjected to analysis. The procedure consists of three steps (see the Figure A). First, HuBuChE is obtained from the victim's plasma. Second, the enzyme is subjected to pepsin proteolysis. Third, the peptide mixture obtained is subjected to LC-MSMS analysis. If no poisoning took place, the peptide mixture contains a non-modified nonapeptide FGESAGAAS. However, cholinesterases are inactivated due to a chemical reaction with Novichok type nerve agent, the modified nonapeptide is be detected, and its exact (high resolution) mass (along with the mass of the secondary ion produced during collision induced dissociation) allows unambiguous identification of the fact of poisoning and the exact structure of the poison. Thus, the example at Figure A shows the masses of the primary and secondary ions obtained from the plasma of the victim poisoned by A-230. If a victim is poisoned by other Novichok type agents, the masses are different.
Leslie Harold Collier (9 February 1921 – 14 March 2011) was a scientist responsible for developing a freeze-drying method to produce a more heat stable smallpox vaccine in the late 1940s. Collier added a key component, peptone, a soluble protein, to the process. This protected the virus, enabling the production of a heat-stable vaccine in powdered form. Previously, smallpox vaccines would become ineffective after 1–2 days at ambient temperature. The development of his vaccine production method played a large role in enabling the World Health Organization to initiate its global smallpox eradication campaign in 1967.
Gaza war: David Cameron, the new foreign secretary, announces sanctions against four senior Hamas leaders and two of the militant group's financiers. Chelsea Ladies Football Club manager Emma Hayes is named as the new manager of the United States women's national football team, and will take up the role in May 2024. 15 November Inflation falls to 4.6%, the lowest rate since November 2021, driven mainly by lower energy prices. The British Government's plan to deport migrants to Rwanda is ruled as unlawful by the Supreme Court. Sunak says the government will introduce "emergency legislation" to enable Parliament to "confirm Rwanda is safe" and prevent legal challenges from blocking the migrant policy. More than 50 Labour MPs defy Sir Keir Starmer to vote for an immediate ceasefire in the Israel-Hamas war. The General Synod of the Church of England votes to allow special church services of blessing for gay couples. 16 November David Cameron makes his first working visit to Ukraine as foreign secretary, where he meets President Volodymyr Zelensky in Kyiv, and reiterates the UK's promise to provide moral, diplomatic and "above all military support for... however long it takes". Train drivers union ASLEF announces new strike dates, with a rolling programme of strikes from 2 to 8 December affecting different train companies on different days. A sixth person is confirmed dead following a house fire in Hounslow, West London.
This can be corrected by purifying the sample as much as possible before LC is performed, but in the case of analyzing environmental samples where everything in the sample is of concern, sample preparation may not be the ideal solution to fix the problem. Another method that can be applied to correct the issue is by using the standard addition method.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.