If you have been reading about Certificate of analysis and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
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.
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.
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.
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.
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.
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.
== Adverse effects == The most common side effects include headache, fever, fall, cough, vomiting, abdominal pain, cold symptoms (nasopharyngitis) and nausea. In animal studies, no significant changes were seen in the male reproductive system of monkeys and mice following weekly subcutaneous administration. According to the reports obtained from the clinical trials, pain at the site of intravenous administration, back pain, oropharyngeal pain, sprain in ligaments, diarrhea, dizziness, contusion, flu, ear infection, rhinitis, skin abrasion, tachycardia, and constipation occurred at an elevated frequency in the treatment group, as compared to their placebo counterparts. Hypersensitivity reactions, including rash, fever, itching, hives, skin irritation (dermatitis) and skin peeling (exfoliation), have occurred in people who were treated with golodirsen. Renal toxicity was observed in animals who received golodirsen. Although renal toxicity was not observed in the clinical studies with golodirsen, potentially fatal glomerulonephritis, has been observed after administration of some antisense oligonucleotides. Renal function should be monitored in those taking golodirsen.
Chloral hydrate is a geminal diol with the formula Cl3C−CH(OH)2. It was first used as a sedative and hypnotic in Germany in the 1870s. Over time it was replaced by safer and more effective alternatives but it remained in use in the United States until at least the 1970s. It sometimes finds usage as a laboratory chemical reagent and precursor. It is derived from chloral (trichloroacetaldehyde) by the addition of one equivalent of water.
All meitnerium isotopes are extremely unstable (radioactive); in general, heavier isotopes are more stable than the lighter. The most stable known isotope, 278Mt (half-life 4.5 seconds), is also the heaviest known. The unconfirmed 282Mt is even heavier and seems to have a longer half-life, 67 seconds. With a half-life of 0.8 seconds, the next most stable known isotope is 270Mt. 276Mt and 274Mt have half-lives of 0.62 and 0.64 seconds respectively. 277Mt, created as the final decay product of 293Ts for the first time in 2012, was observed to undergo spontaneous fission, half-life 5 milliseconds. Preliminary data analysis considered the possibility that this fission is instead from 277Hs, for it also has a half-life of a few milliseconds, and could come from undetected electron capture somewhere in the decay chain. This possibility was later deemed very unlikely based on observed decay energies of 281Ds and 281Rg and the short half-life of 277Mt, although there is still some uncertainty of the assignment. Regardless, the rapid fission of 277Mt and 277Hs is strongly suggestive of a region of instability for superheavy nuclei with N = 168–170. The existence of this region, characterized by a decrease in fission barrier height between the deformed shell closure at N = 162 and spherical shell closure at N = 184, is consistent with theoretical models.
=== Insulin lispro === Insulin lispro, marketed under the brand name Humalog among others, is a modified form of medical insulin used to treat both type 1 and type 2 diabetes. It is administered subcutaneously through injection or an insulin pump. The effects typically begin within 30 minutes and last for about 5 hours. Sometimes, a longer-acting insulin, such as insulin NPH, is also used. Common side effects include low blood sugar, while more serious side effects may include low blood potassium. It is generally considered safe for use during pregnancy and breastfeeding. It functions similarly to human insulin by increasing glucose uptake in tissues and reducing the amount of glucose produced by the liver in gluconeogenesis. Insulin lispro was first approved for use in the United States in 1996. It is a synthetic analogue of human insulin, created by swapping two amino acids. In 2022, it ranked as the 70th most commonly prescribed medication in the United States, with over 9 million prescriptions. Insulin lispro is available under a generic label from Lilly.
=== Activity === This enzyme participates in 8 metabolic pathways: alanine and aspartate metabolism, methionine metabolism, valine, leucine and isoleucine degradation, tyrosine metabolism, phenylalanine metabolism, tryptophan metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and alkaloid biosynthesis. It employs one cofactor, flavin adenine dinucleotide (FAD). The enzyme binds to FAD in the first step of the catalytic process, thereby reducing FAD to FADH2. The FAD is regenerated from FADH2 by oxidation as a result of O2 being reduced to H2O2. The mechanism proceeds via oxidative deamination of the L-amino acid, which affords an imino acid intermediate. Following hydrolysis of the intermediate, the enzyme successfully affords the 2-oxo acid, as shown in Scheme 1.
Sources: en.wikipedia.org
Sinners (Original Motion Picture Soundtrack) won Outstanding Original Score for TV/Film and Outstanding Soundtrack/Compilation Album. On the same day, the Brit Awards 2026 were held. Olivia Dean won British Album of the Year for The Art of Loving, British Artist of the Year and Best Pop Act. Sault won Best R&B Act.
== Legacy == Duttaroy's research focuses on how the placenta transports maternal plasma DHA and ARA to the fetus. The fetal brain development in utero is critically dependent on the maternal supply of these fatty acids in the utero. His studies have been documented through several articles. Besides, his articles have drawn many citations (Google Scholar PubMed). His other research area is cardioprotective factors in fruits and vegetables. He has discovered the anti-platelet factors from tomatoes. This discovery made by him is now widely known as Fruitflow. In 2009, Fruitflow® became the first product in Europe to obtain an approved, proprietary health claim under Article 13(5) of the European Health Claims Regulation 1924/2006 on nutrition and health claims made on foods. The EU Commission authorized the health claim "water-soluble tomato concentrate (WSTC) I and II help maintain normal platelet aggregation, which contributes to healthy blood flow." Fruitflow® is now widely available in different countries worldwide.
== Release and promotion == III was released digitally on November 7, 2012, in the United States, and the CD was released on November 8 in Australia, Canada, and the United States. The album's first two singles, "Plague" and "Wrath of God", were made available for free download on the duo's SoundCloud page on July 25 and September 26, 2012, respectively. The accompanying music video for "Plague" debuted on September 24, 2012, and uses footage from Andrzej Żuławski's 1981 film Possession. "Affection" was released as the album's third single on October 31, 2012. The music video for "Affection" premiered on April 26, 2013, and was filmed on the duo's South American tour. "Violent Youth" premiered on Zane Lowe's BBC Radio 1 show on November 1, 2012. A music video for "Sad Eyes", shot in Berlin and Toronto, was released on January 20, 2013. On July 26, 2012, Crystal Castles announced a North American tour with Health and Kontravoid in support of the album, as well as festivals appearances in Europe and Australia, starting on August 9, 2012, and ending on January 28, 2013. In November 2012, the band performed six dates in the United Kingdom. Additional dates across Europe, Oceania, North America, and South America were announced on October 17, 2012, and January 9, 2013. III is The Last Album to Feature Alice Glass, along with the current Roman numeral pattern
Tribhuvan University was the first public university in Nepal. It operates through six different institutes and is affiliated with various colleges. There are government-funded Purbanchal University and Pokhara University.
==== Origin ==== There are two hypotheses about the evolution of color change in cephalopods. One hypothesis is that the ability to change color may have evolved for social, sexual, and signaling functions. Another explanation is that it first evolved because of selective pressures encouraging predator avoidance and stealth hunting. For color change to have evolved as the result of social selection the environment of cephalopods' ancestors would have to fit a number of criteria. One, there would need to be some kind of mating ritual that involved signaling. Two, they would have to experience demonstrably high levels of sexual selection. And three, the ancestor would need to communicate using sexual signals that are visible to a conspecific receiver. For color change to have evolved as the result of natural selection different parameters would have to be met. For one, one would need some phenotypic diversity in body patterning among the population. The species would also need to cohabitate with predators which rely on vision for prey identification. These predators should have a high range of visual sensitivity, detecting not just motion or contrast but also colors. The habitats they occupy would also need to display a diversity of backgrounds.
Sources: en.wikipedia.org
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.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
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.