A practical reference on Semax: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-10. Anything still debated is marked as such rather than presented as settled.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
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.
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 during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
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.
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.
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.
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.
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.
=== Articles === Rosen, DR; Siddique, T; Patterson, D; Figlewicz, DA; Sapp, P; Hentati, A; Donaldson, D; Goto, J; O'Regan, JP; Deng, HX; et al. (1993). "Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosis". Nature. 364 (6435): 362. Bibcode:1993Natur.364..362R. doi:10.1038/364362c0. PMID 8332197. Gusella, JF; Wexler, NS; Conneally, PM; Naylor, SL; Anderson, MA; Tanzi, RE; Watkins, PC; Ottina, K; Wallace, MR; Sakaguchi, AY; Young, AB; Shoulson, I; Bonilla, E; Martin, JB (1983). "A polymorphic DNA marker genetically linked to Huntington's Disease". Nature. 306 (5940): 234–238. Bibcode:1983Natur.306..234G. doi:10.1038/306234a0. PMID 6316146. S2CID 4320711. Tanzi, RE; Gusella, JF; Watkins, PC; Bruns, GAP; St; George-Hyslop, PH; Van Keuren, ML; Patterson, D; Pagan, S; Kurnit, DM; Neve, RL. (1987). "The amyloid beta protein gene: cDNA cloning, mRNA distribution, and genetic linkage near the Alzheimer locus". Science. 235 (4791): 880–884. Bibcode:1987Sci...235..880T. doi:10.1126/science.2949367. PMID 2949367. Tanzi, RE; McClatchey, AI; Lamperti, ED; V-Komaroff, L; Gusella, JF; Neve, R (1988). "Protease inhibitor domain encoded by an amyloid protein precursor mRNA associated with Alzheimer's disease". Nature. 331 (6156): 528–530. Bibcode:1988Natur.331..528T. doi:10.1038/331528a0. PMID 2893290. S2CID 4277294.
Bacterial Inclusion Bodies Contain Amyloid-Like Structure at SciVee Amyloid Cascade Hypothesis Amyloid: Journal of Protein Folding Disorders web page Role of anesthetics in Alzheimer's disease: Molecular details revealed
The need for an international standard for chemistry was first addressed in 1860 by a committee headed by German scientist Friedrich August Kekulé von Stradonitz. This committee was the first international conference to create an international naming system for organic compounds. The ideas that were formulated at that conference evolved into the official IUPAC nomenclature of organic chemistry. IUPAC is a legacy of this meeting, making it one of the most important historical international collaborations of chemistry societies. IUPAC as such was established in 1919.Since this time, IUPAC has been the official organization with the responsibility of updating and maintaining official organic nomenclature. One notable country excluded from early IUPAC was Germany. Germany's exclusion was a result of prejudice towards it by the Allied powers after World War I. Germany was finally admitted into IUPAC in 1929. However, Nazi Germany was removed from IUPAC during World War II. At this time, IUPAC was affiliated with the Allied powers, but had little involvement with the war effort itself. East and West Germany were only readmitted to IUPAC in 1973. Since World War II, IUPAC has focused on standardizing nomenclature and methods in science. In 2016, IUPAC denounced the use of chlorine as a chemical weapon. In a letter to Ahmet Üzümcü, director of the Organisation for the Prohibition of Chemical Weapons (OPCW), the organization pointed out their concerns in regards to chlorine weapon usage in the Syrian civil war and other places .
The following is a list of fentanyl analogues (sometimes referred to as fentalogs), and includes both compounds developed by pharmaceutical companies for legitimate medical use, and those which have been sold as designer drugs. The latter have been reported to national drug control agencies such as the DEA, and some to transnational agencies such as the EMCDDA and UNODC. This is not a comprehensive or exhaustive list of fentanyl analogues, as more than 1400 compounds from this family have been described in the scientific and patent literature. However, this list does include many notable compounds that have reached late-stage human clinical trials, and compounds which have been sold as designer drugs, as well as representative examples of significant structural variations reported in the scientific and patent literature. The structural variations among fentanyl analogues can impart profound pharmacological differences between each other, especially regarding potency and efficacy. In the United States, the Drug Enforcement Administration (DEA) placed the class of "Fentanyl-Related Substances" on the list of Schedule I drugs in 2018, making it illegal to manufacture, distribute, or possess fentanyl analogs, with very broad terminology being used in its scheduling. Regarding the temporary control of fentanyl-related substances, Schedule I was extended through December 31, 2024 by Public Law 117-328.
Sources: en.wikipedia.org
==== Detection in body fluids ==== Morphine and its major metabolites, morphine-3-glucuronide, and morphine-6-glucuronide, can be detected in blood, plasma, hair, and urine using an immunoassay. Chromatography can be used to test for each of these substances individually. Some testing procedures hydrolyze metabolic products into morphine before the immunoassay, which must be considered when comparing morphine levels in separately published results. Morphine can also be isolated from whole blood samples by solid phase extraction (SPE) and detected using liquid chromatography-mass spectrometry (LC-MS). Ingestion of codeine or food containing poppy seeds can cause false positives. A 1999 review estimated that relatively low doses of heroin (which metabolizes immediately into morphine) are detectable by standard urine tests for 1–1.5 days after use. A 2009 review determined that, when the analyte is morphine and the limit of detection is 1 ng/ml, a 20 mg intravenous (IV) dose of morphine is detectable for 12–24 hours. A limit of detection of 0.6 ng/ml had similar results.
==== Wound healing ==== Clients who are cleaned by blue tang benefit after suffering an injury. Blue tangs incur many minor injuries, but infection as a result of injuries rarely leads to death. Recovery rates from both minor and major injuries are very high in blue tangs. Injured blue tangs are found to spend more time in cleaning stations compared to those further along in the healing process. This indicates that cleaning plays an important role in the wound healing process. Cleaners pick at the wound and eat the dead tissue in the peripheral area.
Silver sulfadiazine, sold under the brand Silvadene among others, is a topical antibiotic used in partial thickness (second-degree) and full thickness (third-degree) burns to prevent infection. Tentative evidence has found other antibiotics to be more effective, and therefore it is no longer generally recommended for second-degree burns, but is still widely used to protect third-degree burns. Common side effects include itching and pain at the site of use. Other side effects include low white blood cell levels, allergic reactions, bluish grey discoloration of the skin, red blood cell breakdown, or liver inflammation. Caution should be used in those allergic to other sulfonamides. It should not be used in pregnant women who are close to delivery. It is not recommended for use in children less than two months of age. Silver sulfadiazine was first described in 1943 as the precipitate formed from reacting sodium sulfadiazine with silver nitrate in water, and rediscovered in the 1960s as a topical treatment for burns. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2022, it was the 279th most commonly prescribed medication in the United States, with more than 700,000 prescriptions.
Sources: en.wikipedia.org
Greer (born 1945), American chemist notable for work on thermodynamics of fluids, polymer solutions and phase transitions François Auguste Victor Grignard (1871–1935), French chemist, 1912 Nobel Prize in Chemistry for his work on reactions important in the formation of carbon–carbon bonds Robert H. Grubbs (1942–2021), 2005 Nobel Prize in Chemistry for work on olefin metathesis Louis-Bernard Guyton de Morveau (1737–1816), French chemist known for establishing modern chemical nomenclature
Colistimethate sodium may be used to treat Pseudomonas aeruginosa infections in patients with cystic fibrosis, and it has come into recent use for treating multidrug-resistant Acinetobacter infection, although resistant forms have been reported. Colistimethate sodium has also been given intrathecally and intraventricularly in Acinetobacter baumannii and Pseudomonas aeruginosa meningitis and ventriculitis Some studies have indicated that colistin may be useful for treating infections caused by carbapenem-resistant isolates of Acinetobacter baumannii. Colistin sulfate may be used to treat intestinal infections, or to suppress colonic flora. Colistin sulfate is also used in topical creams, powders, and otic solutions. Colistin A (polymyxin E1) and colistin B (polymyxin E2) can be purified individually to research and study their effects and potencies as separate compounds.
== Etymology == The term was coined in 1995 from cathelin, due to the characteristic cathelin-like domain present in cathelicidins. The name cathelin itself is coined from cathepsin L inhibitor in 1989.
leptonema Also leptotene stage. In meiosis, the first of five substages of prophase I, following interphase and preceding zygonema. During leptonema, the replicated chromosomes condense from diffuse chromatin into long, thin strands that are much more visible within the nucleus.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.