This is a working overview of lyophilised powder, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-03 and is reviewed periodically as new material appears.
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.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
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.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
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.
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.
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.
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.
== Invertebrates == Tendon cells form a connecting epithelial layer between the muscle and shell in molluscs. In gastropods, for example, the retractor muscles connect to the shell via tendon cells. Muscle cells are attached to the collagenous myo-tendon space via hemidesmosomes. The myo-tendon space is then attached to the base of the tendon cells via basal hemidesmosomes, while apical hemidesmosomes, which sit atop microvilli, attach the tendon cells to a thin layer of collagen. This is in turn attached to the shell via organic fibres which insert into the shell. Molluscan tendon cells appear columnar and contain a large basal cell nucleus. The cytoplasm is filled with granular endoplasmic reticulum and sparse golgi. Dense bundles of microfilaments run the length of the cell connecting the basal to the apical hemidesmosomes.
=== Successful prevention and identification === The first successful preventive measure against beriberi was discovered by Takaki Kanehiro, a British-trained Japanese medical doctor of the Imperial Japanese Navy, in the mid-1880s. Beriberi was a serious problem in the Japanese navy; sailors fell ill an average of four times a year in the period 1878 to 1881, and 35% were cases of beriberi. In 1882, Takaki learned of a very high incidence of beriberi among cadets on a training mission from Japan to Hawaii, via New Zealand and South America. The voyage lasted more than nine months and resulted in 169 cases of sickness and 25 deaths on a ship of 376 men. Takaki observed that beriberi was common among low-ranking crew who were often provided free rice, thus ate little else, but not among crews of Western navies, nor among Japanese officers who consumed a more varied diet. With the support of the Japanese Navy, he conducted an experiment in which another ship was deployed on the same route, except that its crew was fed a diet of meat, fish, barley, rice, and beans. At the end of the voyage, this crew had only 14 cases of beriberi and no deaths. Takaki's results of his experiment impressed the Japanese Navy, which adopted his proposed solution. By 1887, beriberi had been eliminated on Navy ships. In the same year, Takaki's experiment was described favorably in The Lancet, but his nutritional deficiency etiology was not taken seriously, with Western medicine overwhelmingly favoring miasmatic theories, believing the disease to be caused either by microorganisms or toxins.
Cohen (1952), former co-owner of the Boston Celtics and the Brooklyn Nets; former chairman and CEO of the Madison Square Garden Corporation Lawrence K. Grossman (1952), president of PBS 1976–1984 and NBC News 1985–1988 Richard Wald (1952), former president of NBC News 1973–1977 Robert A. Belfer (1955), oilman and philanthropist, namesake of the Belfer Center for Science and International Affairs at Harvard University Thomas Ludlow Chrystie II (1955), first chief financial officer of Merrill Lynch & Company and creator of the Cash Management Account Alfred Lerner (1955), chairman of MBNA Bank and ex-owner of the Cleveland Browns Richard Ravitch (1955), chairman of the Metropolitan Transportation Authority and the Bowery Savings Bank Sid Sheinberg (1955), head of Universal Pictures Barry F. Sullivan (1955), chairman and CEO of First Chicago Bank, deputy mayor of New York City under David Dinkins Edward Botwinick (1956), IT entrepreneur and inventor, co-founder of Timeplex Franklin A. Thomas (1956), former president of The Ford Foundation James R. Barker (1957), chairman of Interlake Steamship Company, former chairman and CEO of Moore-McCormack Peter L.
In the UK no formal qualification or certification is required prior to becoming a phlebotomist as training is usually provided on the job. The NHS offers training with formal certification upon completion.
Sources: en.wikipedia.org
Philip J. Currie suggested that Tyrannosaurus may have been pack hunters, comparing T. rex to related species Tarbosaurus bataar and Albertosaurus sarcophagus, citing fossil evidence that may indicate gregarious (describing animals that travel in herds or packs) behavior. A find in South Dakota where three T. rex skeletons were in close proximity may suggest the formation of a pack. Cooperative pack hunting may have been an effective strategy for subduing prey with advanced anti-predator adaptations which pose potential lethality such as Triceratops and Ankylosaurus. Currie's pack-hunting T. rex hypothesis has been criticized for not having been peer-reviewed, but rather was discussed in a television interview and book called Dino Gangs. The Currie theory for pack hunting by T. rex is based mainly by analogy to a different species, Tarbosaurus bataar. Evidence of gregariousness in T. bataar itself has not been peer-reviewed, and to Currie's own admission, can only be interpreted with reference to evidence in other closely related species. According to Currie gregariousness in Albertosaurus sarcophagus is supported by the discovery of 26 individuals with varied ages in the Dry Island bonebed. He ruled out the possibility of a predator trap due to the similar preservation state of individuals and the near absence of herbivores. Additional support of tyrannosaurid gregariousness can be found in fossilized trackways from the Upper Cretaceous Wapiti Formation of northeastern British Columbia, Canada, left by three tyrannosaurids traveling in the same direction.
== Regeneration == In order for an injury to be healed by regeneration, the cell type that was destroyed must be able to replicate. Cells also need a collagen framework along which to grow. Alongside most cells there is either a basement membrane or a collagenous network made by fibroblasts that will guide the cells' growth. Since ischaemia and most toxins do not destroy collagen, it will continue to exist even when the cells around it are dead.
PCP is both water- and lipid-soluble and is therefore distributed throughout the body quickly. PCP is metabolized into PCHP, PPC and PCAA. The drug is metabolized 90% by oxidative hydroxylation in the liver during the first pass. Metabolites are glucuronidated and excreted in the urine. Nine percent of ingested PCP is excreted in its unchanged form. When smoked, some of the compound is broken down by heat into 1-phenylcyclohexene (PC) and piperidine. The time taken before the effects of PCP manifest is dependent on the route of administration. The onset of action for inhalation occurs in 2–5 minutes, whereas the effects may take 15 to 60 minutes when ingested orally.
Sources: en.wikipedia.org
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.