peptidase raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-11-08 and is reviewed periodically as new material appears.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
In the case of neutrophilic pericholangitis, neutrophils surround the portal ducts and obstruct them. Neutrophilic pericholangitis has a variety of causes including endotoxemia, Hodgkin's disease, among others. Cholangitis lenta can also cause changes to the portal tracts. This occurs during chronic cases of sepsis and results in dilation of the bile ductules. Cholangitis lenta is likely a result of a stoppage of bile secretion and bile flow through the ductules. Back pressure created from obstructive cholestasis can cause dilation of the bile duct and biliary epithelial cell proliferation, mainly in the portal tracts. Portal tract edema may also occur as a result of bile retention, as well as periductular infiltration of neutrophils. If the obstruction is left untreated, it can lead to a bacterial infection of the biliary tree. Infection is mostly caused by coliforms and enterococci and is evident from a large migration of neutrophils to the duct lumina. This can result in the formation of a cholangitic abscess. With treatment, many of the histological features of cholestasis can be corrected once the obstruction is removed. If the obstruction is not promptly resolved, portal tract fibrosis can result. Even with treatment, some fibrosis may remain.
=== September === 2 September The UK government suspends the sale of some UK arms to Israel, citing a "clear risk" they may be used to commit serious violations of international law. One word Ofsted assessments for schools in England are scrapped with immediate effect, and following the January 2023 death of Ruth Perry, a headteacher who committed suicide after her school received a poor Ofsted grading. The Household Support Fund, used to help people with cost-of-living payments, is extended by the UK government. A winter vaccination programme to protect newborn babies and older people against respiratory syncytial virus (RSV) is launched in England, Wales and Northern Ireland. British endurance swimmer Sam Farrow is believed to have set a new world record after swimming the length of Lake Geneva in 22 hours and 48 minutes. The UK has experienced its coolest summer since 2015, Met Office data has confirmed. 3 September Gaza war: The UK suspends 30 out of 350 arms export licences to Israel. The UK government awards nine offshore wind farm contracts totalling 4.9 gigawatts (GW), as part of the drive towards achieving 60GW by 2030. Six children and six adults die attempting to cross the Channel from France to England. 4 September Publication of the report into the Grenfell tower fire, which blames "dishonest" companies and a string of failures by successive governments. The extradition hearing of Kimberlee Singler, a US woman accused of killing two of her children in Colorado in December 2023, begins in London.
=== Wrongful death lawsuits === Carrey's girlfriend Cathriona White married Mark Burton in 2013, in Las Vegas. She and Carrey had been dating on and off since 2012, and she was still married but dating Carrey when she died in 2015. On September 19, 2016, Burton filed a wrongful death lawsuit against Carrey, claiming that he had used his "immense wealth and celebrity status" to illegally obtain and distribute prescription drugs involved in White's death. Carrey released a statement the following day:
Sources: en.wikipedia.org
== Contraindications == Phenelzine is contraindicated in patients who are unable or unwilling to follow the required dietary tyramine restrictions and medication precautions, and in patients with pheochromocytoma because of the risk of hypertensive emergency. This contraindication reflects a preventable risk: tyramine-related hypertensive emergencies are uncommon when dietary and medication precautions are followed, and modern food standards have substantially reduced excessive tyramine exposure compared with the period when MAOIs were first introduced. It is also contraindicated with drugs, supplements, or recreational drugs that have significant serotonin reuptake inhibition or significant serotonin-releasing activity, because of the risk of serotonin toxicity. Examples include selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs), clomipramine, imipramine, MDMA, and certain analgesics such as meperidine, tramadol, methadone, tapentadol, dextromethorphan, dextropropoxyphene, pentazocine, and levorphanol. Concomitant use of multiple MAO-inhibiting agents is generally listed as contraindicated or avoided in prescribing guidance. For combinations of classic MAOIs with one another, the caution is based mainly on limited safety data and the fact that routine long-term coadministration usually has little therapeutic rationale, since classic MAOIs already inhibit both MAO-A and MAO-B irreversibly.
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, carboxy tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus.
Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid, is an aminopolycarboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, slightly water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly.
In New Zealand, Undaria pinnatifida was declared as an unwanted organism in 2000 under the Biosecurity Act 1993. It was first discovered in Wellington Harbour in 1987 and probably arrived as hull fouling on shipping or fishing vessels from Asia. In 2010, a single Undaria pinnatifida plant was discovered in Fiordland, which has since quickly spread from a small clump and localized itself throughout Fiordland. Wakame is now found around much of New Zealand, from Stewart Island to as far north as the subtropical waters of Karikari Peninsula. It spreads in two ways: naturally, through the millions of microscopic spores released by each fertile organism, and through human mediated spread, most commonly via hull fouling and with marine farming equipment. It is a highly successful and fertile species, which makes it a serious invader. Its capability to grow in dense congregations on any hard surface allows it to outcompete native flora and fauna for sunlight and space. Although the effects of wakame in New Zealand are not fully understood, with the severity varying depending on the location, the negative impact of wakame is projected to be significant against the fishing and tourism industries in Fiordland, as well as overcrowding in popular diving locations. Even though it is an invasive species, farming of wakame is permitted in already heavily infested areas of New Zealand, as part of a control program established since 2010. In 2012, the government allowed for the farming of wakame in Wellington, Marlborough and Banks Peninsula.
Sources: en.wikipedia.org
In Mesopotamia, early pictorial evidence for beer drinking includes a 6,000-year-old Sumerian seal from Tepe Gawra, dating to around 4000 BC, which depicts two figures drinking beer through long reed straws from a communal bowl. Chemical analysis of pottery from Godin Tepe in the central Zagros Mountains of present-day Iran provides evidence of barley beer from about 5,500 years ago, with fragments of a jug found to contain deposits of beerstone, a by-product associated with brewing. A 3900-year-old Sumerian poem honouring Ninkasi, the patron goddess of brewing, contains the oldest surviving beer recipe, describing the production of beer from barley via bread. The production of bread and beer has been argued to be responsible for humanity's ability to develop technology and build civilisation. Beer may have been known in Neolithic Europe as far back as 5,000 years ago, Brewing remained largely a household activity in early medieval Europe, although beer was also produced commercially and in monasteries. Ale produced before the Industrial Revolution continued to be made and sold on a domestic scale, while during the early Middle Ages beer was also being produced and sold by European monasteries. During the Industrial Revolution, the production of beer moved from artisanal to industrial manufacture, and domestic manufacture ceased to be significant by the end of the 19th century. The development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process, and greater knowledge of the results.
Two functionally unequal subpopulations of neutrophils were identified on the basis of different levels of their reactive oxygen metabolite generation, membrane permeability, activity of enzyme system, and ability to be inactivated. The cells of one subpopulation with high membrane permeability (neutrophil-killers) intensively generate reactive oxygen metabolites and are inactivated in consequence of interaction with the substrate, whereas cells of another subpopulation (neutrophil-cagers) produce reactive oxygen species less intensively, don't adhere to substrate and preserve their activity. Additional studies have shown that lung tumors can be infiltrated by various populations of neutrophils.
Monetary policy is the process by which the monetary authority of a country, generally central bank controls the supply of money in the economy. In India, the central monetary authority is the Reserve Bank of India (RBI).
21 April – Mark Menzies quits the Conservative Party and says he will stand down from Parliament at the next election. Robin Swann, who is the perspective Ulster Unionist candidate for South Antrim, announces he will step down from his post as Northern Ireland's Health Minister once the general election campaign begins. 22 April – Parliament passes the Safety of Rwanda Bill, with plans to deport the first asylum seekers to Kigali in July. Two men, including a parliamentary researcher, are charged with spying for China after providing information that could be "useful to an enemy". Conservative councillor Richard Solesbury-Timms, who represents Middleton Cheney on West Northamptonshire Council, leaves the party to sit as an independent citing the party's dealing with allegations against the council leader. 23 April – Patrick Harvie says he will resign as co-leader of the Scottish Greens if the party votes to end its coalition agreement with the SNP. Alliance Party MLA Patrick Brown resigns his South Down seat in the Northern Ireland Assembly, citing personal reasons for doing so. 24 April – Rishi Sunak vows to increase UK defence spending to 2.5% of GDP by 2030. Labour unveils its plans for improvements to train services, which include automatic refunds for delays, a "best price" guarantee and improved internet coverage. Jeffrey Donaldson appears at Newry Magistrates' Court to face charges of historic child abuse. Johnny Timpson, the UK's inaugural disability ambassador, resigns over the UK government's policy of clawing back benefit overpayment.
* The 1947 elections had just a complementary character at the federal level (since the deputies elected in 1945 had mandates until 1950) and elected the State Chambers according to the new Constitution. The PCB elected 46 state deputies and become a major party in the Federal District (at this time, the city of Rio de Janeiro). ** The party didn't launch any candidates to the Senate, choosing to support other parties' candidates, following the party tactics of a "democratic front".
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.