If you have been reading about Heptapeptide 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 2026-07-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
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.
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.
== Career and writing == After leaving Oxford, Halliwell briefly lectured at the Portsmouth Polytechnic (1973–74). He took up a position as lecturer at King's College London in 1974, remaining there until 2000, rising to the position of Professor of Medical Biochemistry in the Division of Pharmacology. He also simultaneously held a visiting professorship at the University of California, Davis, United States (1995–99). After a 1998 sabbatical at the National University of Singapore (NUS), he moved there in 2000 as chair of the biochemistry department. As of 2018 he is a professor in the department of biochemistry at the NUS Yong Loo Lin School of Medicine. Halliwell is currently the Senior Advisor, Academic Appointments and Research Excellence, Office of the Provost, at the National University of Singapore (NUS). He is also Chairman of the Biomedical Research Advisory Council (BMAC), Agency for Science, Technology & Research (A*STAR). Halliwell served as the NUS's first Deputy President (Research and Technology) in 2006–15, founding the Graduate School for Integrative Sciences and Engineering, and overseeing a more than doubling in the university's research grants and the creation at NUS of Singapore's first Research Centre of Excellence (RCEs). He was subsequently appointed Senior Advisor to the NUS President. His textbook, Free Radicals in Biology and Medicine, co-written with John M. C. Gutteridge, is considered "an authoritative text in the field".
The pharmacology of 3-CMC is expected to be very similar to the pharmacology for other mephedrone analogs (methcathinones). These molecules interact with monoamine transporters, in particular the dopamine transporter (DAT), norepinephrine transporter (NET), and serotonin transporter (SERT) . The main function of these transporters is to terminate monoamine transmission by reuptake of the released neurotransmitters. Interaction of psychoactive drugs with the monoamine transporters inhibits this reuptake leading to an increase in the concentration of dopamine, norepinephrine and serotonin in the synaptic cleft. Specifically, 3-chloromethcathinone (3-CMC) and other ring-substituted methcathinone derivatives act as substrates for monoamine transporters MATs (and subsequently competitive inhibitors), through which they are actively translocated into the cytoplasm of the presynaptic nerve terminal. Once inside the cytosol, they interact with the vesicular monoamine transporter 2 (VMAT2) as substrates, disrupting the vesicular proton gradient and facilitating the collapse of synaptic vesicles. This causes the release of stored neurotransmitters into the cytoplasm. The resulting high concentration of cytosolic neurotransmitters subsequently triggers the reversal of MAT transport direction, leading to carrier-mediated efflux of the neurotransmitters into the synaptic cleft. Furthermore, simple ring-substituted cathinones contrast with traditional amphetamines by lacking significant affinity for the intracellular trace amine-associated receptor 1 (TAAR1).
Solvents can have a powerful effect on solubility, stability, and reaction rate. A change in solvent can also allow a chemist to influence the thermodynamic or kinetic control of the reaction. Reactions proceed at different rates in different solvents due to the change in charge distribution during a chemical transformation. Solvent effects may operate on the ground state and/or transition state structures. An example of the effect of solvent on organic reactions is seen in the comparison of SN1 and SN2 reactions. Solvent can also have a significant effect on the thermodynamic equilibrium of a system, for instance as in the case of keto-enol tautomerizations. In non-polar aprotic solvents, the enol form is strongly favored due to the formation of an intramolecular hydrogen-bond, while in polar aprotic solvents, such as methylene chloride, the enol form is less favored due to the interaction between the polar solvent and the polar diketone. In protic solvents, the equilibrium lies towards the keto form as the intramolecular hydrogen bond competes with hydrogen bonds originating from the solvent.
Sources: en.wikipedia.org
== Function == The protein encoded by this gene belongs to the family of G-protein coupled receptors that are preferentially activated by adenosine and uridine nucleotides. Two alternatively spliced transcript variants encoding the same protein isoform have been found for this gene.
It is particularly concerning as those consequences happen while the brain is still developing. The degree to which the sleep is disturbed and fragmented has been significantly linked to the severity of the consequences, the latter having the possibility to decrease once the sleep is improved. It is more the disruption of sleep processes than the total amount of sleep the child experience that generates the adverse consequences on the child's daytime functioning; it contributes to the hyperactivity for example. Children with OSA may experience learning and memory deficits, and OSA has been linked to lowered childhood IQ scores. Untreated OSA may prevent children from reaching their height potential.
=== Non-medical use === Though not an approved drug, LGD-4033 (Ligandrol) has been sold on the black market as a designer drug in countries where it is classified as an illegal substance. Along with enobosarm (ostarine; GTx-024, S-22), andarine (GTx-007; S-4), and vosilasarm (RAD140; "testolone"), LGD-4033 is one of the most popular and common non-medically-used SARMs. Many products sold online that are purported to be LGD-4033 either contain none or contain other unrelated substances, and doses are also frequently not as labeled. Social media has played an important role in facilitating the widespread non-medical use of SARMs. On 23 October 2017, a nutritional supplement company in Missouri called Infantry Labs was warned by the FDA that the distribution of two of its products violated the Federal Food, Drug, and Cosmetic Act. One of the substances was LGD-4033. The company advertised as benefits of the LGD-4033: "increases in lean body mass and decrease in body fat" and "increases in strength, well being, as well as healing possibilities". The company mislabeled as "dietary supplements" what should have been "new drugs" or "prescription drugs" and were instructed to document the steps they would take in order to cease the violation. Also on 23 October 2017, the FDA sent a warning letter to a New Jersey company called Panther Sports Nutrition. The company's marketing approach for the product was similar to that of the Infantry Labs case, and the product was advertised as a "mass builder" and "physique enhancing agent".
Injection: Clinical doses of oxytocin are given by injection either into a muscle or into a vein to cause contraction of the uterus. Very small amounts (< 1%) do appear to enter the central nervous system in humans when peripherally administered. The compound has a half-life of typically about 3 minutes in the blood when given intravenously. Intravenous administration requires 40 minutes to reach a steady-state concentration and achieve maximum uterine contraction response. Buccal: Oxytocin was delivered in buccal tablets, but this is not common practice any more. Under the tongue: Oxytocin is poorly absorbed sublingually. Nasal administration: Oxytocin is effectively distributed to the brain when administered intranasally via a nasal spray, after which it reliably crosses the blood–brain barrier and exhibits psychoactive effects in humans. No serious adverse effects with short-term application of oxytocin with 18~40 IU (36–80 mcg) have been recorded. Intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 hours. Oral: While it was originally assumed that oxytocin administered orally would be destroyed in the gastrointestinal tract, studies have shown that oxytocin is transported by the immunoglobulin RAGE (receptor for advanced glycation end products) across the intestinal epithelium and into the blood. Orally-administered oxytocin has been shown to increase putamen responses to facial emotions in humans.
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.