This is a working overview of Selank, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
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.
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.
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
=== Home media === The film arrived on domestic videocassette on October 30, 1991, through Columbia TriStar Home Video. It fared more respectably on the home market, shipping close to 140,000 units at launch. The film was reissued on domestic DVD by MGM Home Entertainment on June 12, 2007. It made its domestic Blu-ray debut through Olive Films on June 23, 2015. Kino Lorber will release the film on 4K Blu-ray on April 26, 2026.
Cognitive neuroscience addresses the questions of how psychological functions are produced by neural circuitry. The emergence of powerful new measurement techniques such as neuroimaging (e.g., fMRI, PET, SPECT), EEG, MEG, electrophysiology, optogenetics and human genetic analysis combined with sophisticated experimental techniques from cognitive psychology allows neuroscientists and psychologists to address abstract questions such as how cognition and emotion are mapped to specific neural substrates. Although many studies hold a reductionist stance looking for the neurobiological basis of cognitive phenomena, recent research shows that there is an interplay between neuroscientific findings and conceptual research, soliciting and integrating both perspectives. For example, neuroscience research on empathy solicited an interdisciplinary debate involving philosophy, psychology and psychopathology. Moreover, the neuroscientific identification of multiple memory systems related to different brain areas has challenged the idea of memory as a literal reproduction of the past, supporting a view of memory as a generative, constructive and dynamic process. Neuroscience is also allied with the social and behavioral sciences, as well as with nascent interdisciplinary fields. Examples of such alliances include neuroeconomics, decision theory, social neuroscience, and neuromarketing to address complex questions about interactions of the brain with its environment.
Iodine-131 (131I) is a beta-emitting isotope with a half-life of 8.0249 days, and comparatively energetic (0.61 MeV) beta radiation, which penetrates 0.6 to 2.0 mm from the site of uptake. This beta radiation can be used for the destruction of thyroid nodules or hyperfunctioning thyroid tissue and for elimination of remaining thyroid tissue after surgery for the treatment of Graves' disease. The purpose of this therapy, which was first explored by Dr. Saul Hertz in 1941, is to destroy thyroid tissue that could not be removed surgically. In this procedure, 131I is administered either intravenously or orally following a diagnostic scan. This procedure may also be used, with higher doses of radio-iodine, to treat patients with thyroid cancer. The 131I is taken up into thyroid tissue and concentrated there. The beta particles emitted by the radioisotope destroys the associated thyroid tissue with little damage to surrounding tissues (more than 2.0 mm from the tissues absorbing the iodine). Due to similar destruction, 131I is the iodine radioisotope used in other water-soluble iodine-labeled radiopharmaceuticals (such as MIBG) used therapeutically to destroy tissues. The high energy beta radiation (up to 606 keV) from 131I causes it to be the most carcinogenic of the iodine isotopes.
== Clinical significance == The clinical significance in humans is becoming clear. From parallels in the mouse studies, there may be diseases where its function could be relevant. In a mouse model of thalassemia, its expression is increased, resulting in iron overload, which is also a feature of the human disease. A role in the recovery from the anemia of inflammation in mice has been shown and involvement in inherited anemias with ineffective erythropoiesis, anemia of chronic kidney diseases and iron-refractory iron-deficiency anemia has been suggested. Erythroferrone levels in blood have been shown by immunoassay to be higher after blood loss or erythropoetin administration. Patients with beta-thalassemia have very high levels, and these decrease after blood transfusion.
Legendre did an impressive amount of work on elliptic functions, including the classification of elliptic integrals, but it took Abel's study of the inverses of Jacobi's functions to solve the problem completely. He is known for the Legendre transformation, which is used to go from the Lagrangian to the Hamiltonian formulation of classical mechanics. In thermodynamics it is also used to obtain the enthalpy and the Helmholtz and Gibbs (free) energies from the internal energy. He is also the namesake of the Legendre polynomials, solutions to Legendre's differential equation, which occur frequently in physics and engineering applications, such as electrostatics. Legendre is best known as the author of Éléments de géométrie, which was published in 1794 and was the leading elementary text on the topic for around 100 years. This text greatly rearranged and simplified many of the propositions from Euclid's Elements to create a more effective textbook.
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Lobeline is a piperidine alkaloid found in a variety of plants, particularly those in the genus Lobelia, including Indian tobacco (Lobelia inflata), Devil's tobacco (Lobelia tupa), great lobelia (Lobelia siphilitica), Lobelia chinensis, and Hippobroma longiflora. In its pure form, it is a white amorphous powder which is freely soluble in water.
Bradykinin is rapidly inactivated in the circulating blood, and it disappears completely in a single pass through the pulmonary circulation. Angiotensin I also disappears in the pulmonary circulation because of its conversion to angiotensin II. Furthermore, angiotensin II passes through the lungs without any loss. The inactivation of bradykinin and the conversion of angiotensin I to angiotensin II in the lungs was thought to be caused by the same enzyme. In 1970, Ng and Vane, using BPF provided by Ferreira, showed the conversion is inhibited during its passage through the pulmonary circulation. BPFs are members of a family of peptides whose potentiating action is linked to inhibition of bradykinin by ACE. Molecular analysis of BPF yielded a nonapeptide BPF teprotide (SQ 20,881), which showed the greatest ACE inhibition potency and hypotensive effect in vivo. Teprotide had limited clinical value as a result of its peptide nature and lack of activity when given orally. In the early 1970s, knowledge of the structure-activity relationship required for inhibition of ACE was growing. David Cushman, Miguel Ondetti and colleagues used peptide analogs to study the structure of ACE, using carboxypeptidase A as a model. Their discoveries led to the development of captopril, the first orally-active ACE inhibitor, in 1975. Captopril was approved by the United States Food and Drug Administration in 1981. The first nonsulfhydryl-containing ACE inhibitor, enalapril, was approved four years later. At least 8 other ACE inhibitors have since been marketed.
Sidestream tobacco smoke, or exhaled mainstream smoke, is particularly harmful. Because exhaled smoke is at lower temperatures than inhaled smoke, chemical compounds undergo changes that can make them more dangerous. Smoke chemical composition undergoes changes in time, which causes the transformation of the compound NO into the more toxic NO2. Further, volatilization causes smoke particles to become smaller, and thus more easily embedded deep into the lungs of anyone breathes them in.
The Ukrainian Air Force claimed that twenty-five missiles were fired at Kyiv and other parts of Ukraine. Twenty-three were intercepted by air defence. While there were no reports of casualties, there was some property damage. Ukraine also said it had moved its Victory Day celebrations to May 8 in line with the rest of Europe, while 9 May will be called Europe Day. French journalist Arman Soldin, who worked for Agence France Presse, was killed in a rocket attack in Chasiv Yar, near Bakhmut. He was with a team of AFP journalists travelling with Ukrainian soldiers when the group came under fire from Grad rockets.
==== Enzymatic ==== The enzymes traditionally used to digest heparin or HS are naturally produced by the soil bacterium Pedobacter heparinus (formerly named Flavobacterium heparinum). This bacterium is capable of using either heparin or HS as its sole carbon and nitrogen source. To do so, it produces a range of enzymes such as lyases, glucuronidases, sulfoesterases, and sulfamidases. The lyases have mainly been used in heparin/HS studies. The bacterium produces three lyases, heparinases I (EC 4.2.2.7), II (no EC number assigned) and III (EC 4.2.2.8) and each has distinct substrate specificities as detailed below.
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=== Absorption === Bicalutamide is extensively and well-absorbed following oral administration, and its absorption is not affected by food. The absolute bioavailability of bicalutamide in humans is unknown due to its very low water solubility and hence lack of an assessable intravenous formulation. However, the absolute bioavailability of bicalutamide has been found to be high in animals at low doses (109% in mice at 10 mg/kg; 72% in rats at 1 mg/kg; 100% in dogs at 0.1 mg/kg), but diminishes with increasing doses such that the bioavailability of bicalutamide is low at high doses (10% in rats at 250 mg/kg; 31% in dogs at 100 mg/kg). In accordance, absorption of (R)-bicalutamide in humans is slow and extensive but saturable, with steady-state levels increasing linearly at a dosage of up to 150 mg/day and non-linearly at higher dosages. At higher dosages of 100 to 200 mg/day, absorption of bicalutamide is approximately linear, with a small but increasing departure from linearity above 150 mg/day. In terms of geometric mean steady-state concentrations of (R)-bicalutamide, the departures from linearity were 4%, 13%, 17%, and 32% with dosages of 100, 150, 200, and 300 mg/day, respectively. There is a plateau in steady-state levels of (R)-bicalutamide with bicalutamide dosages above 300 mg/day, and, accordingly, dosages of bicalutamide of 300 to 600 mg/day result in similar circulating concentrations of (R)-bicalutamide and similar degrees clinically of efficacy, tolerability, and toxicity.
=== Risk factors === Risk factors associated with TIA are categorized as modifiable or non-modifiable. Non-modifiable risk factors include age greater than 55, sex, family history, genetics, and race/ethnicity. Modifiable risk factors include cigarette smoking, hypertension (elevated blood pressure), diabetes, hyperlipidemia, level of carotid artery stenosis (asymptomatic or symptomatic) and activity level. The modifiable risk factors are commonly targeted in treatment options to attempt to minimize risk of TIA and stroke.
ATP synthase, also called complex V, is the final enzyme in the oxidative phosphorylation pathway. This enzyme is found in all forms of life and functions in the same way in both prokaryotes and eukaryotes. The enzyme uses the energy stored in a proton gradient across a membrane to drive the synthesis of ATP from ADP and phosphate (Pi). Estimates of the number of protons required to synthesize one ATP have ranged from three to four, with some suggesting cells can vary this ratio, to suit different conditions.
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Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.