If you have been reading about Neurotrophic factor 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.
Updated 2026-04-04. Numbers and descriptions here follow the published literature rather than marketing material.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
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.
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
| 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 |
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.
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.
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 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.
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.
== Function == The mitochondria in a eukaryotic cell utilize fuels to produce adenosine triphosphate (ATP). This process involves storing energy as a proton gradient, also known as the proton motive force (PMF) generated by moving protons from the mitochondrial matrix (N or negative side) across the mitochondrial inner membrane to the mitochondrial intermembrane space (P or positive side) using the energy released by the electron transport chain. This proton gradient energy is used to synthesize ATP when the protons flow across the membrane (down their concentration gradient - from a region of high proton concentration to a region of lower proton concentration) through the ATP synthase complex; this is known as chemiosmosis. In endotherms, body heat is maintained by signaling the mitochondria to allow protons to move back into the mitochondrial matrix (down their concentration gradient - from a region of high proton concentration to a region of lower proton concentration) without producing ATP (proton leak). This can occur since an alternative return route for the protons exists through an uncoupling protein in the inner membrane. This protein, known as uncoupling protein 1 (thermogenin) - which is unique to brown adipose tissue, facilitates the return of the protons after they have been actively pumped out of the mitochondrial matrix by the electron transport chain. This alternative route for protons uncouples oxidative phosphorylation and the energy in the PMF is instead released as heat.
=== Behavior === Behavioral patterns associated with BPD frequently involve impulsive actions, which may manifest as substance use disorders, binge eating, unprotected sexual encounters, and self-injury, among other self-harming practices. These behaviors are a response to the intense emotional distress experienced by individuals with BPD, serving as an immediate but temporary alleviation of their emotional pain. However, such actions typically result in feelings of shame and guilt, contributing to a recurrent cycle. This cycle typically begins with emotional discomfort, followed by impulsive behavior aimed at mitigating this discomfort, only to lead to shame and guilt, which in turn exacerbates the emotional pain. This escalation of emotional pain then intensifies the compulsion towards impulsive behavior as a form of relief, creating a vicious cycle. Over time, these impulsive responses can become an automatic mechanism for coping with emotional pain. Interventions such as dialectical behavior therapy (DBT) and schema therapy aim to disrupt this cycle by improving emotional regulation, distress tolerance, and adaptive coping strategies.
The University of Wrocław (Polish: Uniwersytet Wrocławski, UWr; Latin: Universitas Wratislaviensis) is a public research university in Wrocław, Poland. It is the largest institution of higher learning in the Lower Silesian Voivodeship, with over 100,000 graduates since 1945, including some 1,900 researchers, among whom many have received the highest awards for their contributions to the development of scientific scholarship. The university was established in 1701 and reconstituted in its current form in 1945, as a direct successor to the previous German University of Breslau. Following the territorial changes of Poland's borders, academics primarily from the Jan Kazimierz University of Lwów restored the university building, which had been heavily damaged in the 1945 Battle of Breslau.
Sources: en.wikipedia.org
=== Interpretation === Accurate interpretation takes a variety of factors into account, such as the thyroid hormones i.e. thyroxine (T4) and triiodothyronine (T3), current medical status (such as pregnancy), certain medications like propylthiouracil, temporal effects including circadian rhythm and hysteresis, and other past medical history.
=== Other plants === Yohimbine has also been isolated from other plant genera in the family Apocynaceae including Lochnera (Catharanthus), Rauvolfia, Amsonia, Vallesia and Vinca; from the family Loganiaceae (genera Gelsemium and Strychnos); and from the family Euphorbiaceae (genus Alchornea).
==== Public perceptions ==== American consumer's perception of foods treated with irradiation was strongly negative in 1992. Some who advocate against food irradiation argue the long-term health effects and safety of irradiated food cannot be scientifically proven, however there have been hundreds of animal feeding studies of irradiated food performed since 1950. Endpoints include subchronic and chronic changes in metabolism, histopathology, function of most organs, reproductive effects, growth, teratogenicity, and mutagenicity.
Sources: en.wikipedia.org
== Airlines and destinations == In 2025, Hohhot Baita International Airport plans to operate 139 routes, serving 92 cities in total, including 83 nonstop destinations and 6 international or regional cities.
=== Digital literacy === Despite being commonly known as "digital natives", Generation Z is not necessarily digitally literate. The 2018 International Computer and Information Literacy Study (ICILS), conducted on 42,000 eighth-graders (or equivalents) from 14 countries, found that only two percent were sufficiently proficient with information devices to justify that description, and only 19% could work independently with computers to gather information and manage their work. In the U.S., 90% reached Level 1, 66% Level 2, 25% Level 3, and 2% Level 4. Among American eighth-graders, 72% said they searched for information on the Internet at least once a week or every school day, and 65% reported they were autodidactic information finders on the Internet. The role of Generation Z in the future "digital economy" remains uncertain as they still lack the skills they need to join the workforce. At least initially, they struggle with office items such as printers or scanners. Many are also unfamiliar with touch typing.
== Settlement == The Judge Donald W. VanArtsdalen of United States District Court ruled that the three had contributed significantly to the Government's case against SmithKline. ordered the government to pay $42.3 million to three men who helped the Justice Department expose Medicare fraud at SmithKline Beecham Clinical Laboratories Inc. The Justice Department had resisted paying the men the 15 to 25 percent share of SmithKline's settlement specified for whistleblowers by the federal False Claims Act. The department argued that most of the $325 million settlement was obtained through its nationwide Labscam investigations that had nothing to do with the men, Robert J. Merena, Charles W. Robinson, Jr., and Glenn Grossenbacher. But U.S. District Judge Donald W. VanArtsdalen ruled Wednesday that they made a major contribution to the government's case and that they helped bring in nearly all of the settlement.
==== Peptide chain ==== Several of the genes responsible for pyoverdine biosynthesis (e.g., pvdH, pvdA, and pvdF) are involved in the generation of precursor and alternate amino acids necessary for various portions of the molecule. Several others (e.g., pvdI, and pvdJ) are directly responsible for "stitching" together the peptide chain. pvdD terminates the chain and releases the precursor into the cytoplasm, which is consistent with identification of pyoverdine-like molecules in the cytoplasm with incompletely matured chromophores.
Sources: en.wikipedia.org
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 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.