If you have been reading about Enkephalinase 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 2026-05-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| 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 |
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.
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.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
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.
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.
=== Metalloproteins === Metalloproteins are conjugated proteins that are characterized by having one or more metal ions attached to the protein as a prosthetic groups. These metal ions could be iron, zinc, copper, magnesium, etc., and these are very important to the biological functions and its protein activity. Metalloproteins are involved in a wide range processes from electron transfer to catalysis. Many enzymes are metalloproteins, since metal ions can act as cofactors in chemical reactions. For example, zinc ions can be associated with enzymes that are responsible for gene expression. Moreover, metalloproteins containing iron often are involved in oxygen transport and redox reactions. In this way, the presence of metal ions allows these proteins to perform certain tasks that would not be possible with amino acids alone.
In another study, the combination of positively charged peptide amphiphiles and negatively charged long biopolymers led to the formation of hierarchically ordered membranes. When the two solutions are brought into contact, electrostatic complexation between the components of each solution creates a diffusion barrier that prevents the mixing of the solutions. Over time, an osmotic pressure difference drives the reptation of polymer chains through the diffusion barrier into the peptide amphiphile compartment, leading to the formation of fibers perpendicular to the interface that grow over time. These materials can be made in the form of flat membranes or as spherical sacs by dropping one solution into the other. These materials are robust enough to handle mechanically and a range of mechanical properties can be accessed by altering growth conditions and time. They can incorporate bioactive peptide amphiphiles, encapsulate cells and biomolecules, and are biocompatible and biodegradable.
The IDF is planning a number of technological upgrades and structural reforms for the future. Training has been increased with greater cooperation between ground, air, and naval units. The Ground Forces are phasing out the M-16 rifle in favor of the IWI Tavor variants, most recently the IWI Tavor X95 flat-top ("Micro-Tavor Dor Gimel"). The outdated M113 armored personnel carriers are being replaced by the new Namer APCs, with 200 ordered in 2014, as well as obtaining the Eitan AFV, and upgrading the IDF Achzarit APCs. The backbone of the Artillery Corps, the M109 howitzer, will be phased out in favor of a still-undecided replacement, with the ATMOS 2000 and Artillery Gun Module under primary consideration. The IDF is planning a future tank to replace the Merkava, which will be able to fire lasers and electromagnetic pulses, run on a hybrid engine, with a crew as small as two, will be faster, and will be better-protected, with emphasis on active protection systems such as the Trophy over armor. The Combat Engineering Corps assimilated new technologies, mainly in tunnel detection and unmanned ground vehicles and military robots, such as remote-controlled IDF Caterpillar D9T "Panda" armored bulldozers, Sahar engineering scout robot and improved Remotec ANDROS robots.
== Biology == Honokiol has been extracted from a number of species of Magnolia native to many regions of the globe. Magnolia grandiflora, which is native to the Southeastern United States, as well as Mexican species like Magnolia dealbata have been found to be sources of honokiol. Traditionally in Asian medicine, the Magnolia biondii, Magnolia obovata, and Magnolia officinalis are commonly used. The compound itself has a spicy odor. Because of its physical properties, honokiol can readily cross the blood–brain barrier and the blood–cerebrospinal fluid barrier. As a result, honokiol is a potentially potent therapy with high bioavailability.
Sources: en.wikipedia.org
87Rb, 187Re, 176Lu, 232Th, and 238U have half-lives long enough that their decay is limited over geological time scales; 40K and 235U have shorter half-lives and are hence severely depleted, but are still long-lived enough to remain present in significant amount on Earth. The longest-lived isotope not proven to be primordial is 146Sm, which has a half-life of 9.20×107 years, followed by 244Pu (8.13×107 years) and 92Nb (3.47×107 years). 244Pu was reported to exist in nature as a primordial nuclide in 1971, but this detection could not be confirmed by further studies in 2012 and 2022. Taking into account that all these nuclides must exist for at least 4.58×109 years, 146Sm must survive 50 half-lives (and hence be reduced by 250 ≈ 1×1015), 244Pu must survive 57 (and be reduced by a factor of 257 ≈ 1×1017), and 92Nb must survive 130 (and be reduced by 2130 ≈ 1×1039). Mathematically, considering the likely initial abundances of these nuclides, primordial 146Sm and 244Pu should persist somewhere within the Earth today, even if they are not identifiable in the relatively minor portion of the Earth's crust available to human assays, while 92Nb and all shorter-lived nuclides should not. Nuclides such as 92Nb that were present in the primordial solar nebula but have long since decayed away completely are termed extinct radionuclides if they have no other means of being regenerated. As for 244Pu, calculations suggest that as of 2022, sensitivity limits were about one order of magnitude away from detecting it as a primordial nuclide.
Intranasal midazolam is found to be highly effective in acute episodes of seizures in children. Recently, the upper part of the nasal cavity, as high as the cribriform plate, has been proposed for drug delivery to the brain. This "transcribrial route", published first in 2014, was suggested by the author for drugs to be given for Primary Meningoencephalitis.
== Structure == NAXE gene is located on chromosome 1, with its specific location being 1q22. The gene contains 6 exons, 5 introns, and spans 2.5 kb. Expression is ubiquitous across all human tissues, with highest observed in kidney, heart, liver, testis, thyroid gland, adrenal gland. NAXE contains Yje_FN domain.
=== Clinical quantification and genotyping === Viruses can be present in humans due to direct infection or co-infections which makes diagnosis difficult using classical techniques and can result in an incorrect prognosis and treatment. The use of qPCR allows both the quantification and genotyping (characterization of the strain, carried out using melting curves) of a virus such as the hepatitis B virus. The degree of infection, quantified as the copies of the viral genome per unit of the patient's tissue, is relevant in many cases; for example, the probability that the type 1 herpes simplex virus reactivates is related to the number of infected neurons in the ganglia. This quantification is carried out either with reverse transcription or without it, as occurs if the virus becomes integrated in the human genome at any point in its cycle, such as happens in the case of HPV (human papillomavirus), where some of its variants are associated with the appearance of cervical cancer. Real-time PCR has also brought the quantization of human cytomegalovirus (CMV) which is seen in patients who are immunosuppressed following solid organ or bone marrow transplantation.
For services to Life Saving. Geoffrey Francis Norris, General Medical Practitioner, London. For services to Medicine. Arthur Joseph Nutter. For services to the Lieutenancy in Lancashire. John O'Neil, lately Principal Lecturer and Course Leader of PGCE Art and Design, University of Wales Institute, Cardiff. For services to Art Education and Teacher Training. Martin Offiah. For services to Rugby Football. Enid Rosalind Oliver. For services to the community in Ashford, Kent. William James Orford. For services to Cricket in the West Midlands. Vera Overs. For services to the community in Martindale, Cumbria. Clifford Owen. For services to the Chorley and District Talking Newspaper, Lancashire. Pamela Mary Owen. For services to the community, particularly the NHS, in Welshpool, Powys. Anthony Gerald Palmer. For services to the War Pensions Committee in East Anglia. Sarah Faith, The Honourable Mrs. Palmer. For services to the community, particularly the British Red Cross Society, in Berkshire. Isobel Marilyn Park. For services to the Scout Association in Dumfries. Gordon Seymour Passmore, Member, London Borough of Wandsworth. For services to Local Government. Norman Henry Pattenden, Special Operations Manager, North & South Railways Ltd. For services to the Railways Industry. William Evans Pattison. For services to Mountain Rescue. Robert John Patton. For services to the Engineering Industry. Christine Anne Pendlebury, Personal Secretary, Home Office. Philippa Helen Perks. For services to the community in Wrington, Bristol.
Sources: en.wikipedia.org
== Contraindications == Contraindications of spironolactone include hyperkalemia (high potassium levels), severe and end-stage kidney disease (due to high hyperkalemia risk, except possibly in those on dialysis), Addison's disease (adrenal insufficiency and low aldosterone levels), and concomitant use of eplerenone. It should also be used with caution in people with certain neurological disorders, as well as those who experience or have experienced anuria (lack of urine production), acute kidney injury, or significant impairment of kidney excretory function with risk of hyperkalemia.
=== 21 May === President Zelenskyy appeared to confirm the fall of Bakhmut to Russia, saying in an interview to AFP that "For today, Bakhmut is only in our hearts" and that "nothing" was left of the city. However, he and his office later clarified that he had not said that the city had fallen. The Ukrainian Defence Ministry said its forces were holding on to a sector of the city while partly encircling Bakhmut itself. A Russian-installed official in occupied Zaporizhzhia Oblast said that the Ukrainian military had attacked the port of Berdiansk with seven missiles, including four British-supplied Storm Shadows. He said six of the missiles had been intercepted and one had fallen on the edge of the city but had not caused any casualties. The Ukrainian military later confirmed that they had struck a Russian headquarters in the city. President Biden confirmed a new military aid package worth $375 million for Ukraine, saying the United States would provide ammunition, artillery, armored vehicles and training. He also said that he received reassurances from President Zelenskyy that any F-16s supplied to Ukraine will not be used for incursions on internationally recognized Russian territory itself. An administrative building in the village of Golovchino in Russia's Belgorod Oblast caught fire. Russian officials blamed the fire on a "quadcopter". Japan announced the delivery of one hundred military vehicles and thirty thousand ration kits to Ukraine.
– indicates that no information is available As a result of heparin's effect on such a wide variety of disease states, a number of drugs are indeed in development whose molecular structures are identical or similar to those found within parts of the polymeric heparin chain.
== Differentiation from internet peptides == Peptide therapeutics are not to be confused with the mid 2020s peptide trend; peptides (some off-label and some illegal) with unconfirmed safety and efficacy have recently become popular through social media influencers. Peptides are fragile, and thus are not generally absorbed by skin. However, emerging techniques such as nano-emulsion allows for some uptake of peptides through the skin. There is insufficient evidence for the safety or efficacy of most injected peptides in humans. Many peptides have only been tested on lab grown cells, and have not yet progressed to testing in animal models or humans. One off-label use of peptides is circumventing bans on the prescription of human growth hormone (HGH) by using tesamorelin or Sermorelin; that approach however carries the same downsides as regular HGH prescription, including increased risk of cancer, diabetes, and abnormal bone growth. Another influencer promoted peptide is TB-500, which has not undergone human testing and which at high levels is associated with tumor development. The United States, under the direction of Robert F. Kennedy Jr., has sought to deregulate various trendy peptides. Many Americans have gained access to "research grade" peptides sourced from China, which are not intended for widespread use. In July 2026, an advisory panel to the FDA (with 14 members, six of whom were peptide sellers), advised the FDA to deregulate six peptides, including BPC-157.
=== Presence in other species === Atherosclerosis primarily affects herbivorous species. Carnivorous animals such as dogs, cats, lions, and tigers can consume diets high in saturated fat and cholesterol without developing atherosclerotic plaques, as demonstrated in various studies. Atherosclerosis can be experimentally induced in carnivorous animals only by thyroidectomy. Removal of the thyroid gland appears to alter lipid metabolism, rendering saturated fat and cholesterol atherogenic in these species, similar to the effect observed in herbivores.
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.
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.