Everything below concerns peptide stability. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-11-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
== Further reading == Batchelor, G.K (2012), An Introduction to Fluid Dynamics, Cambridge University Press, doi:10.1017/CBO9780511800955, ISBN 9780511800955 Falkovich, Gregory (2011), Fluid Mechanics (A short course for physicists), Cambridge University Press, doi:10.1017/CBO9780511794353, ISBN 978-1-107-00575-4 Kundu, Pijush K.; Cohen, Ira M.; Dowling, David R.; Capecelatro, Jesse (2025), Fluid Mechanics (7th ed.), Academic Press, ISBN 978-0-12-819807-0 Currie, I. G. (1974), Fundamental Mechanics of Fluids, McGraw-Hill, Inc., ISBN 0-07-015000-1 Massey, B.; Ward-Smith, J. (2005), Mechanics of Fluids (8th ed.), Taylor & Francis, ISBN 978-0-415-36206-1 Nazarenko, Sergey (2014), Fluid Dynamics via Examples and Solutions, CRC Press (Taylor & Francis group), ISBN 978-1-43-988882-7
=== "Moonlighting" === In addition to its intracellular role as the major actin-sequestering molecule in cells of many multicellular animals, thymosin β4 shows a remarkably diverse range of effects when present in the fluid surrounding animal tissue cells. Taken together, these effects suggest that thymosin has a general role in tissue regeneration. This has suggested a variety of possible therapeutic applications, and several have now been extended to animal models and human clinical trials. It is considered unlikely that thymosin β4 exerts all these effects via intracellular sequestration of G-actin. This would require its uptake by cells, and moreover, in most cases the cells affected already have substantial intracellular concentrations. The diverse activities related to tissue repair may depend on interactions with receptors quite distinct from actin and possessing extracellular ligand-binding domains. Such multi-tasking by, or "partner promiscuity" of, proteins has been referred to as protein moonlighting. Proteins such as thymosins which lack stable folded structure in aqueous solution, are known as intrinsically unstructured proteins (IUPs). Because IUPs acquire specific folded structures only on binding to their partner proteins, they offer special possibilities for interaction with multiple partners. A candidate extracellular receptor of high affinity for thymosin β4 is the β subunit of cell surface-located ATP synthase, which would allow extracellular thymosin to signal via a purinergic receptor.
In video games, for example, drugs are portrayed in a variety of ways: including power-ups (cocaine gum replenishes stamina in Red Dead Redemption 2), obstacles to be avoided (such as the Fuzzies in Super Mario World 2: Yoshi's Island that distort the player's view when accidentally consumed), items to be bought and sold for in-game currency (coke dealing is a big part of Scarface: The World Is Yours). In the Fallout video game franchise, drugs ("chems" in the game) can fill the role of any above mentioned. Drug trafficking, gang rivalries, and their related criminal underworld also play a big part in the Grand Theft Auto video game franchise.
{\displaystyle \mu ={\frac {1}{j+1}}{\Bigl \langle }(l,s),j,m_{j}{=}j\,{\Bigr |}\left({\frac {1}{2}}{\vec {l}}{g^{(l)}}_{p}+{\frac {1}{2}}{\vec {s}}({g^{(s)}}_{p}+{g^{(s)}}_{n})\right)\cdot {\vec {\jmath }}\,{\Bigl |}\,(l,s),j,m_{j}{=}j{\Bigr \rangle }}
Sources: en.wikipedia.org
After hearing arguments for and against Luke, Viserys decides to reaffirm Luke's status as heir to Driftmark, which enrages Vaemond. Vaemond calls Rhaenyra a "whore" and her children "bastards", which angers Viserys into declaring that he will have Vaemond's tongue for such speech, though Daemon decapitates Vaemond before he can do so. Viserys hosts a feast among the two sides of his family, where he implores them to make amends for their past conflicts. Rhaenyra and Alicent compliment each other, and the family eats and laughs in harmony for the first time in years. Viserys is glad to see his family united, and departs for bed before Alicent and Rhaenyra's families become tense once again. As he lays in bed, Viserys mistakes Alicent for Rhaenyra and vocalizes Aegon the Conqueror's Song of Ice and Fire to her, with Alicent interpreting his words to mean that he wants her son Aegon to succeed him as king. He calls out to his "love" Aemma in his last words, and passes away shortly after on his bed.
== Academic and professional activities == Throughout 37 years of activity, Mendes published some 150 articles, During this time, he created various inventions and innovations in the field of Implant Surgery, Bio materials, Orthopedic instruments and surgical techniques. As a result, he is the owner of several international patents. Mendes introduced the Total Knee Arthroplasty operation for the first time in Israel, a technology he studied in the USA. By combining materials developed in Germany and France, he was able to extend the service life of the implant. As part of his activities in the Center for Implant Surgery, Mendes created a platform for cooperation with researchers from the Technion, the Hebrew University and the high tech industry. These efforts were directed at the investigation of influence of different types of energy on bone restructure and fracture healing, development of new implants and replacement parts for joints and ligaments and contributed to the arising field of Computed Tomography. Together with International teams financed by the German-Israel Foundation, Mendes managed several research efforts into the replacement of ligaments with synthetic fibers and the design of artificial replacement of the bony patella.
Dean Ho is a Provost's Chair Professor in the Departments of Biomedical Engineering and Pharmacology, Director of the N.1 Institute for Health, Director of the Institute for Digital Medicine, and Head of the Department of Biomedical Engineering at the National University of Singapore. He was previously a professor at UCLA, and associate professor in the Departments of Biomedical Engineering and Mechanical Engineering in the Robert R. McCormick School of Engineering and Applied Science, and Full Member of the Robert H. Lurie Comprehensive Cancer Center at the Feinberg School of Medicine of Northwestern University, Illinois, United States.
=== Mediterranean and ancient Greece === Among the Hellenes, Egyptians, and others, vegetarianism had medical or ritual purification purposes. Vegetarianism was also practiced in ancient Greece and the earliest reliable evidence for vegetarian theory and practice in Greece dates from the 6th century BCE. The Orphics, a religious movement spreading in Greece at that time, also practiced and promoted vegetarianism. Greek teacher Pythagoras, who promoted the altruistic doctrine of metempsychosis, may have practiced vegetarianism, but is also recorded as eating meat. A fictionalized portrayal of Pythagoras appears in Ovid's Metamorphoses, in which he advocates a form of strict vegetarianism. It was through this portrayal that Pythagoras was best known to English-speakers throughout the early modern period and, prior to the coinage of the word "vegetarianism", vegetarians were referred to in English as "Pythagoreans". Vegetarianism was also practiced about six centuries later in another instance (30 BCE–50 CE) in the northern Thracian region by the Moesi tribe (who inhabited present-day Serbia and Bulgaria), feeding themselves on honey, milk, and cheese.
=== Storage and excretion === How fast B12 levels change depends on the balance between how much B12 is obtained from the diet, how much is secreted and how much is absorbed. The total amount of vitamin B12 stored in the body is about 2–5 mg in adults. Around 50% of this is stored in the liver. Approximately 0.1% of this is lost per day by secretions into the gut, as not all these secretions are reabsorbed. Bile is the main form of B12 excretion; most of the B12 secreted in the bile is recycled via enterohepatic circulation. Excess B12 beyond the blood's binding capacity is typically excreted in urine. Owing to the extremely efficient enterohepatic circulation of B12, the liver can store 3 to 5 years' worth of vitamin B12; therefore, nutritional deficiency of this vitamin is rare in adults in the absence of malabsorption disorders. In the absence of intrinsic factor or distal ileum receptors, only months to a year of vitamin B12 are stored.
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.