Certificate of analysis raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-11-19. Anything still debated is marked as such rather than presented as settled.
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.
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.
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 |
|---|---|---|
| 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 |
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.
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.
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.
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.
=== Guatemala === The URNG condemned the US military action and demanded the withdrawal of the US forced from the region and the release of Maduro. Winaq condemned the US military action saying it was not "to the defense of democracy or human rights, but to the historical interests of imperialism to appropriate the strategic resources of the people".
ANUBL1; BAG1; BAT3/BAG6; C1orf131; DDI1; DDI2; FAU; HERPUD1; HERPUD2; HOPS; IKBKB; ISG15; LOC391257; MIDN; NEDD8; OASL; PARK2; RAD23A; RAD23B; RPS27A; SACS; 8U SF3A1; SUMO1; SUMO2; SUMO3; SUMO4; TMUB1; TMUB2; UBA52; UBB; UBC; UBD; UBFD1; UBL4A; UBL4B; UBL7; UBLCP1; UBQLN1; UBQLN2; UBQLN3; UBQLN4; UBQLNL; UBTD1; UBTD2; UHRF1; UHRF2;
On 6 October 2015, Microsoft unveiled the latest version of their Microsoft Surface Book laptop with a display of "over 6 million pixels" and their new phones the Microsoft Lumia 950 and 950 XL, which, aside from 4K video recording that their predecessors included, feature a display of "over 5 million pixels". On 8 December 2015, the ceremony of the opening of the Holy Door in Vatican City, which marked the beginning of the Jubilee Year of Mercy in the Roman Catholic church, was the first worldwide Ultra HD broadcast via satellite. The event was produced by the Vatican Television Center with the support of Eutelsat, Sony, Globecast and DBW Communication. The team did some advanced experimentation with 4K/High Dynamic Range live images and in particular using technology developed by the BBC's R&D division and Japan's public broadcaster NHK in terms of Hybrid Log Gamma (HLG) signals.
Sources: en.wikipedia.org
=== Marine === Laboratory cultures of marine phytoplankton (Phaeodactylum tricornutum, Phaeocystis sp., Thalassiosira weissflogii, Chaetoceros calcitrans, Isochrysis sp., Porphyridium sp., Synechococcus sp., Tetraselmis sp., Prorocentrum sp., and Emiliana huxleyi) produce CH3Cl, but in relatively insignificant amounts. An extensive study of 30 species of polar macroalgae revealed the release of significant amounts of CH3Cl in only Gigartina skottsbergii and Gymnogongrus antarcticus.
=== Radio === Following stints working in radio in Southern California and Honolulu, French became morning DJ on the Seattle radio station KIRO in 1959. He left KIRO in 1971 and moved to KVI, where he produced and wrote radio dramas. French was dismissed from his position at KVI in 1978, and he returned to KIRO in as a host 1980. He stepped down from his position as a host in 1994. In 1996, French began production of the radio drama program Imagination Theatre, which in 2003 moved to KIXI. His syndicated programs are now broadcast on over 120 stations in the U.S. and Canada and are also broadcast via XM Satellite Radio throughout North America. In January 2017, it was announced that, due to age and health issues, French and his family would be closing down their production company, Jim French Productions, and discontinuing all broadcasts of Imagination Theatre at the end of March 2017. Imagination Theatre was relaunched in 2019, following a successful crowdfunding campaign headed by actors and producers John Patrick Lowrie and Larry Albert, and is now produced by Aural Vision, LLC.
This is in contrast to many progestins, such as 19-nortestosterone derivatives (e.g., norethisterone, levonorgestrel, dienogest) and 17α-hydroxyprogesterone derivatives (e.g., cyproterone acetate, medroxyprogesterone acetate), which do bind to the AR and have been associated with significant androgenic or antiandrogenic effects depending on the progestin in question. Due to its lack of androgenic and antiandrogenic activity, and hence lack of masculinizing and feminizing effects, progesterone is one of the few progestogens that is suitable for use during pregnancy in women at risk for preterm birth or recurrent miscarriage.
=== Tendons === Quinolones are associated with a risk of tendonitis and tendon rupture; a 2013 review found the incidence of tendon injury among those taking fluoroquinolones to be between 0.08 and 0.20%. The risk appears to be higher among people older than 60 and those also taking corticosteroids; the risk also may be higher among people who are male, have a pre-existing joint or tendon issue, have kidney disease, or are highly active. Some experts have advised avoidance of fluoroquinolones in athletes. If tendonitis occurs, it generally appears within one month, and the most common tendon injured appears to be the Achilles tendon. The cause is not well understood.
Sources: en.wikipedia.org
The pylorus, the lowest section of the stomach which attaches to the duodenum via the pyloric canal, contains countless glands which secrete digestive enzymes including gastrin. After an hour or two, a thick semi-liquid called chyme is produced. When the pyloric sphincter, or valve opens, chyme enters the duodenum where it mixes further with digestive enzymes from the pancreas, and then passes through the small intestine, where digestion continues. The parietal cells in the fundus of the stomach, produce a glycoprotein called intrinsic factor which is essential for the absorption of vitamin B12. Vitamin B12 (cobalamin), is carried to, and through the stomach, bound to a glycoprotein secreted by the salivary glands – transcobalamin I also called haptocorrin, which protects the acid-sensitive vitamin from the acidic stomach contents. Once in the more neutral duodenum, pancreatic enzymes break down the protective glycoprotein. The freed vitamin B12 then binds to intrinsic factor which is then absorbed by the enterocytes in the ileum. The stomach is a distensible organ and can normally expand to hold about one litre of food. This expansion is enabled by a series of gastric folds in the inner walls of the stomach. The stomach of a newborn baby will only be able to expand to retain about 30 ml.
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=== Perforated === Perforated steel belts enable the drying media, for example hot air, to be transferred 'through' the belt, so that the air is in contact with all parts of the product on the belt. Normally, manufacturers offer perforated belts with five standard perforation patterns which cover most requirements. Other patterns, with a minimum hole diameter of 0.8 mm (0.03 in.) and different spacing, can be provided to suit specific applications.
Sources: en.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.
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.