tuftsin is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-03-30. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
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.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Gene Expression Omnibus (GEO) A database of high-throughput functional genomics and gene expression data derived from experimental assays and next-generation sequencing and managed by the National Center for Biotechnology Information.
==== Reaction with lipids ==== Hypochlorous acid reacts with unsaturated bonds in lipids, but not saturated bonds, and the ClO− ion does not participate in this reaction. This reaction occurs by hydrolysis with addition of chlorine to one of the carbons and a hydroxyl to the other. The resulting compound is a chlorohydrin. The polar chlorine disrupts lipid bilayers and could increase permeability. When chlorohydrin formation occurs in lipid bilayers of red blood cells, increased permeability occurs. Disruption could occur if enough chlorohydrin is formed. The addition of preformed chlorohydrin to red blood cells can affect permeability as well. Cholesterol chlorohydrin have also been observed, but do not greatly affect permeability, and it is believed that Cl2 is responsible for this reaction. Hypochlorous acid also reacts with a subclass of glycerophospholipids called plasmalogens, yielding chlorinated fatty aldehydes which are capable of protein modification and may play a role in inflammatory processes such as platelet aggregation and the formation of neutrophil extracellular traps.
== Routine maintenance == As with any piece of instrumentation or equipment, there are many aspects of maintenance that need to be encompassed by daily, weekly and annual procedures. The frequency of maintenance is typically determined by the sample volume and cumulative run time that the instrument is subjected to. One of the first things that should be carried out before the calibration of the ICP-MS is a sensitivity check and optimization. This ensures that the operator is aware of any possible issues with the instrument and if so, may address them before beginning a calibration. Typical indicators of sensitivity are Rhodium levels, Cerium/Oxide ratios and DI water blanks. One common standard practice is to measure a standard tuning solution provided by the ICP manufacturer every time the plasma torch is started. Then the instrument is auto-calibrated for optimum sensitivity and the operator obtains a report providing certain parameters such as sensitivity, mass resolution and estimated amount of oxidized species and double-positive charged species. One of the most frequent forms of routine maintenance is replacing sample and waste tubing on the peristaltic pump, as these tubes can get worn fairly quickly resulting in holes and clogs in the sample line, resulting in skewed results. Other parts that will need regular cleaning and/or replacing are sample tips, nebulizer tips, sample cones, skimmer cones, injector tubes, torches and lenses.
Sources: en.wikipedia.org
Austin held on to the WWF Championship until SummerSlam on August 22 when he lost it to Mankind in a triple threat match also featuring Triple H. in the two months that followed, Triple H would gain possession of the title. Austin would get his rematch at No Mercy on October 17 against Triple H, but Austin lost after The Rock accidentally struck him with a sledgehammer shot meant for Triple H. The three were advertised for a triple-threat match at Survivor Series on November 14, where Austin was run down by a car. The segment was to write him off television, with the neck injury suffered two years prior posing a real threat of early retirement, and was advised to undergo surgery. Austin would later describe this as "the worst storyline I was ever involved in". Austin made a one-off appearance at Backlash on April 30, 2000, attacking Triple H and Vince McMahon to help The Rock reclaim the WWF Championship. After Austin's official return at Unforgiven on September 24, Commissioner Mick Foley led an investigation to find out who ran Austin over, with the culprit revealed to be Rikishi. At No Mercy on October 22, Austin faced Rikishi in a No Holds Barred match, during which Austin attempted to run Rikishi down in a truck, but was prevented from doing so by officials, and the match was deemed a no contest; Austin was subsequently arrested. During a handicap match against Rikishi and Kurt Angle, Triple H came down with the apparent intention of teaming with Austin, only to hit Austin with a sledgehammer and reveal he had instructed Rikishi to run him over.
Smoke signals – indigenous peoples throughout North America developed smoke signals as a form of long-distance visual communication. A signaler would build a fire on an elevated point, using damp grass or leaves to produce thick smoke, and then manipulate the smoke using a wet blanket or hide to create distinct puffs, spirals, or columns visible for up to fifty miles across the Plains. Each tribe devised its own private code, agreed upon in advance between sender and receiver, so that enemies could not interpret the messages. Signals were used to warn of danger, announce the presence of game, coordinate hunting parties and war movements, and call people to gatherings. In the Southwest, the Ancestral Puebloans constructed stone towers on hilltops to facilitate signaling with smoke, fire, and mirrors across vast distances. The Yámana of Tierra del Fuego also used smoke signals to alert neighboring groups when a whale had washed ashore, so that the meat could be shared before it spoiled. Smoking pipe – indigenous Americans invented the smoking pipe and in particular the ceremonial pipe a type of tobacco pipe. This was an unknown concept to Europeans and the idea was adopted by them and was shortly thereafter brought to the Chinese. Snowshoes – invented and then used first in the Americas by the indigenous tribes, which resided in the cold areas of North America in order to travel across a snow-laden landscape, especially during the long winter months, that gripped all of the region. Spinning top – known from Mesoamerican times. A device used as a toy and made out of wood.
The insulin receptor's endogenous ligands include insulin, IGF-I and IGF-II. Using a cryo-EM, structural insight into conformational changes upon insulin binding was provided. Binding of ligand to the α-chains of the IR dimeric ectodomain shifts it from an inverted V-shape to a T-shaped conformation, and this change is propagated structurally to the transmembrane domains, which get closer, eventually leading to autophosphorylation of various tyrosine residues within the intracellular TK domain of the β-chain. These changes facilitate the recruitment of specific adapter proteins such as the insulin receptor substrate proteins (IRS) in addition to SH2-B (Src Homology 2 - B ), APS and protein phosphatases, such as PTP1B, eventually promoting downstream processes involving blood glucose homeostasis. Strictly speaking the relationship between IR and ligand shows complex allosteric properties. This was indicated with the use of a Scatchard plots which identified that the measurement of the ratio of IR bound ligand to unbound ligand does not follow a linear relationship with respect to changes in the concentration of IR bound ligand, suggesting that the IR and its respective ligand share a relationship of cooperative binding. Furthermore, the observation that the rate of IR-ligand dissociation is accelerated upon addition of unbound ligand implies that the nature of this cooperation is negative; said differently, that the initial binding of ligand to the IR inhibits further binding to its second active site - exhibition of allosteric inhibition.
Sexual dimorphism exists in some species. Individuals of one sex, usually males develop secondary sexual characteristics that increase their chances of reproductive success. In dolphinfish, males have larger and blunter heads than females. In several minnow species, males develop swollen heads and small bumps known as breeding tubercles during the breeding season. The male green humphead parrotfish has a more well-developed forehead with an "ossified ridge" which plays a role in ritualised headbutting. Dimorphism can also take the form of differences in coloration. Again, it is usually the males that are brightly coloured; in killifishes, rainbowfishes and wrasses the colours are permanent while in species like minnows, sticklebacks, darters and sunfishes, the colour changes with seasons. Such coloration can be very conspicuous to predators, showing that the drive to reproduce can be stronger than that to avoid predation. Males that have been unable to court a female successfully may try to achieve reproductive success in other ways. In sunfish species, like the bluegill, larger, older males known as parental males, which have successfully courted a female, construct nests for the eggs they fertilise. Smaller satellite males mimic female behaviour and coloration to access a nest and fertilise the eggs. Other males, known as sneaker males, lurk nearby and then quickly dash to the nest, fertilising on the run. These males are smaller than satellite males.
Sources: en.wikipedia.org
=== Alternative medicine === Despite the lack of evidence, castor oil is sometimes claimed to be able to cure diseases. According to the American Cancer Society, "available scientific evidence does not support claims that castor oil on the skin cures cancer or any other disease."
=== Ectendomycorrhiza === Although the Hartig net forms outside the root cells, penetration of plant cortical cells occasionally occurs. Many species of ectomycorrhizal fungi can function either as ectomycorrhizas or in the penetrative mode typical of arbuscular mycorrhizas, depending on the host. Because these associations represent a form of symbiosis in between arbuscular mycorrhizas and ectomycorrhizas, they are termed ectendomycorrhizas.
==== Infrastructure ==== The conflict resulted in widespread destruction in Lebanon that was particularly seen in the south, east, and Dahieh—the southern suburbs of the capital, Beirut. According to the World Bank, 99,209 houses were damaged during the conflict, of which 18% were destroyed. By 31 October 2024, nearly 25% of the buildings in towns near the border were damaged or destroyed, with the most destruction occurring in Kfar Kila and Ayta ash-Shaab. Roughly 80% of the damage occurred after 2 October. In the areas that the IDF had captured during its ground invasion into Lebanon, 42% of buildings were destroyed, according to NBC News. Amnesty International reported the damaging or destruction of over 10,000 buildings between October 2024 and January 2025, with 70% of the buildings in Yaroun, Dhayra, and Al-Bustan being severely damaged or destroyed. UN-Habitat reported that 27% of buildings in Marjayoun and 15% of buildings in Bint Jbeil were damaged or destroyed, while the mayor of Kfar Kila stated that 90% of the homes in the village were destroyed during the conflict, with the remaining 10% sustaining damage. The scale of destruction in Dahieh was comparable to the 2006 Lebanon war, with 353 buildings in the area being destroyed and more than 6,000 houses damaged. The Hezbollah-linked newspaper Al Akhbar reported that the cost of damages in Dahieh was $630 million. More than 60 schools have been destroyed since September 2024, according to Save the Children.
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.