This is a working overview of Certificate of analysis, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-26. Anything still debated is marked as such rather than presented as settled.
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.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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.
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.
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.
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.
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.
Holzschnitzel werden in einem Kochprozess chemisch behandelt. Die Fasern werden durch zwölf- bis fünfzehnstündiges Kochen von den Inkrusten, den unerwünschten Holzbestandteilen, Begleitstoffen, von Cellulose getrennt. Chemisch betrachtet besteht Holz aus:
40 % bis 50 % Cellulose 10 % bis 15 % Hemicellulose 20 % bis 30 % Lignin 6 % bis 12 % sonstige organische Stoffe 0,3 % bis 0,8 % anorganische Stoffe Es gibt das Sulfatverfahren, das Sulfitverfahren und das Natronverfahren, die nach den eingesetzten Kochchemikalien unterschieden werden. Das Organocell-Verfahren ist eine neue Entwicklung. Vor allem enthaltenes Restlignin färbt den Zellstoff nach dem Kochen gelblich bis braun, er muss also gereinigt und gebleicht werden. Restlignin und andere unerwünschte Stoffe werden beim Bleichen herausgelöst, chemische Aufhellung beseitigt Verfärbungen. Der gebleichte Zellstoff wird entwässert. Er wird nun entweder direkt zu Papier verarbeitet oder zu Rollen aufgewickelt. Die Ausbeute ist bei der Zellstoffherstellung geringer als bei der Holzstoffherstellung. Zellstofffasern aber haben den Vorteil, dass sie länger, fester und geschmeidiger sind. Aus Nadelholz gewonnene Zellstofffasern sind ca. 2,5 mm bis 4 mm lang, aus Laubholz gewonnene sind etwa 1 mm lang. Der größte Teil, ca. 85 % des benötigten Zellstoffs, vor allem Sulfatzellstoff, wird aus den skandinavischen Ländern, USA und Kanada importiert. Sulfatzellstoff ist im Vergleich zu Sulfitzellstoff langfaseriger und reißfester, somit wird er hauptsächlich für die Herstellung hochweißer Schreib- und Druckpapiere verwendet. Sulfitzellstoff findet überwiegend Verwendung bei der Herstellung weicher Hygienepapiere.
Der Faserstoff muss gebleicht werden, damit daraus weißes Papier entstehen kann. Traditionell wurde der Zellstoff mit Chlor gebleicht. Das führt jedoch zu einer hohen Belastung der Abwässer mit organischen Chlorverbindungen (AOX). Modernere Verfahren ersetzten Chlor durch Chlordioxid für ECF-Zellstoffe (elemental chlorine free, ohne elementares Chlor). Aufgrund der höheren Oxidationswirkung und der besseren Selektivität von Chlordioxid sinkt die AOX-Belastung um 60 bis 80 %. Wird vollständig auf Chlorverbindungen verzichtet und Sauerstoff, Ozon, Peroxoessigsäure und Wasserstoffperoxid verwendet, wird der Zellstoff mit TCF (totally chlorine free) bezeichnet. Papier aus ECF-Zellstoffen wird als chlorarm bezeichnet, (es sind noch Chlorverbindungen vorhanden). Chlorarme Druckpapiere sind in hochweißer Qualität schon ab einer flächenbezogenen Masse von 51 g/m² herstellbar, chlorfreie erst ab 80 g/m². TCF-Zellstoff hat eine geringere Faserfestigkeit als chlorgebleichter oder ECF. Vorwiegend aus Holzstoff hergestelltes Papier heißt holzhaltig, im Handel mittelfein. Da Lignin, Harze, Fette und Gerbstoffe im Faserbrei verbleiben, sind sie von geringerer Qualität als holzfreie Papiere.
==== Organocell-Verfahren ==== Das Anfang der 1990er Jahre in Kelheim erprobte, aber wirtschaftlich gescheiterte Organocell-Verfahren dient der schwefelfreien und damit umweltfreundlicheren Zellstoffproduktion. In mehreren Kochstufen werden die Holzschnitzel in einem Ethanol-Wasser-Gemisch unter Zusatz von Natronlauge bei Temperaturen von bis zu 190 °C unter Druck aufgeschlossen. Dabei lösen sich Lignin und Hemicellulose. Es folgen verschiedene Waschstufen, in denen der Zellstoff von der Kochflüssigkeit befreit wird, sowie das Bleichen und Entwässern. Der Zellstoff wird in drei Stufen gebleicht:
Sources: de.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.