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.
This page was last updated on 2026-02-24 and is reviewed periodically as new material appears.
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.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
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.
| 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 |
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
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.
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.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
=== In health care === In pharmaceutics, hairstyling, personal hygiene, and cosmetics, emulsions are frequently used. These are usually oil and water emulsions but dispersed, and which is continuous depends in many cases on the pharmaceutical formulation. These emulsions may be called creams, ointments, liniments (balms), pastes, films, or liquids, depending mostly on their oil-to-water ratios, other additives, and their intended route of administration. The first five are topical dosage forms, and may be used on the surface of the skin, transdermally, ophthalmically, rectally, or vaginally. A highly liquid emulsion may also be used orally, or may be injected in some cases. Microemulsions are used to deliver vaccines and kill microbes. Typical emulsions used in these techniques are nanoemulsions of soybean oil, with particles that are 400–600 nm in diameter. The process is not chemical, as with other types of antimicrobial treatments, but mechanical. The smaller the droplet the greater the surface tension and thus the greater the force required to merge with other lipids. The oil is emulsified with detergents using a high-shear mixer to stabilize the emulsion so that when emulsion nano-droplets encounter the lipids in the cell membrane or cell envelope of bacteria or viruses, they force those lipids to merge with the nano-droplets. On a mass scale, this effectively disintegrates the membrane and kills the pathogen.
== History == Colonies of B. cereus were originally isolated by Percy F. Frankland from a gelatine plate left exposed to the air in a cow shed in 1887. In the 2010s, examination of warning letters issued by the US Food and Drug Administration issued to pharmaceutical manufacturing facilities addressing facility microbial contamination revealed that the most common contaminant was B. cereus. Several new enzymes have been discovered in B. cereus, such as AlkC and AlkD, both of which are involved in DNA repair.
=== Opioid withdrawal === Naltrexone should not be started until several (typically 7–10) days of abstinence from opioids have been achieved. This is due to the risk of acute opioid withdrawal if naltrexone is taken, as naltrexone will displace most opioids from their receptors. The time of abstinence may be shorter than 7 days, depending on the half-life of the specific opioid taken. Some physicians use a naloxone challenge to determine whether an individual has any opioids remaining. The challenge involves giving a test dose of naloxone and monitoring for opioid withdrawal. If withdrawal occurs, naltrexone should not be started.
Sources: en.wikipedia.org
=== 1990s === The 1990s laid the groundwork for genomics and regenerative medicine. In 1990, the international Human Genome Project was officially launched with the goal of mapping and sequencing the entire human genome. The same year marked the first approved human gene therapy clinical trial, conducted by W. French Anderson to treat severe combined immunodeficiency (SCID). In 1996, researchers led by Ian Wilmut successfully cloned the first mammal from an adult somatic cell, Dolly the sheep. Shortly thereafter, in 1998, James Thomson isolated human embryonic stem cells, opening new avenues for regenerative medicine and tissue engineering.
==== Absorption ==== Tiagabine is nearly completely absorbed (>95%) and has an oral bioavailability of 90%. The time to peak levels is approximately 1 hour, with a range of 0.8 to 1.5 hours. Peak levels occur after 45 minutes in a fasted state and after 2.5 hours when taken with a high-fat meal. A high fat meal decreases peak levels by 40% but does not affect area-under-the-curve levels, indicating that it delays absorption but does not reduce the extent of absorption. Tiagabine was administered with food in clinical trials and it is recommended that it be taken with food. The pharmacokinetics of tiagabine are linear over a dose range of 2 to 24 mg. Steady-state levels are achieved after 2 days of continuous dosing and there is no accumulation with repeated administration. There have been found to be secondary peaks in circulating tiagabine levels which is suggestive of enterohepatic recycling.
=== Generic names === Metenolone is the generic name of the drug and its INNTooltip International Nonproprietary Name, while methenolone is its BANTooltip British Approved Name. It has also been referred to as methylandrostenolone. This synonym should not be confused with methandrostenolone, which is another name for a different AAS known as metandienone.
March 30 – Both houses of the New York State Legislature pass a bill to legalize recreational cannabis in New York, which, upon being signed by governor Andrew Cuomo the following day, made New York the 15th state to legalize recreational cannabis. March 31 2021 Orange, California office shooting – Four people are killed and two others, including the suspect, are injured in a shooting at an office building. President Biden unveils a $2 trillion infrastructure plan. Governor Greg Gianforte signs a bill that bans Sanctuary cities in the state of Montana into law. Montana becomes the 13th state to ban sanctuary cities.
Sources: en.wikipedia.org
==== Progestogenic activity ==== Many 19-nortestosterone derivatives, including nandrolone, trenbolone, ethylestrenol (ethylnandrol), metribolone (R-1881), trestolone, 11β-MNT, dimethandrolone, and others, are potent agonists of the progesterone receptor (PR) and hence are progestogens in addition to AAS. Similarly to the case of estrogenic activity, the progestogenic activity of these drugs serves to augment their antigonadotropic activity. This results in increased potency and effectiveness of these AAS as antispermatogenic agents and male contraceptives (or, put in another way, increased potency and effectiveness in producing azoospermia and reversible male infertility).
Louis, Missouri; Integrative Technologies for Advancing Scientific Cores ABRF 2014, 23–25 March, Albuquerque, New Mexico; Team Science and Big Data: Cores at the Frontier ABRF 2013, 2–5 March, Palm Springs, California; Tools for the Advancement of Convergence Science ABRF 2012, 17–20 March, Orlando, Florida; Learning From Biomolecules ABRF 2011, 19–22 February, San Antonio, Texas; Technologies to Enable Personalized Medicine ABRF 2010, 20–23 March, Sacramento, California; Translating Basic Research With Advances in Biomolecular Technology ABRF 2009, 7–10 February, Memphis, Tennessee; Application and Optimization of Existing and Emerging Biotechnologies ABRF 2008, 9–12 February, Salt Lake City, Utah; Enabling Technologies in the Life Sciences ABRF 2007, 31 March- 3 April, Tampa, Florida; Creating the Biological Roadmap ABRF 2006, 11–14 February, Long Beach, California; Integrating Science, Tools and Technologies with Systems Biology ABRF 2005, 5–8 February, Savannah, Georgia; BioMolecular Technologies: Discovery to Hypothesis ABRF 2004, 28 February – 2 March, Portland, Oregon; Integrating Technologies in Proteomics and Genomics ABRF 2003, 10–13 February, Denver, Colorado; Translating Biology Using Proteomics and Functional Genomics ABRF 2002, 9–12 March, Austin, Texas; Biomolecular Technologies: Tools for Discovery in Proteomics and Genomics ABRF 2001, 24–27 February, San Diego, CA; The New Biology: Technology for resolving Macromolecular Communications ABRF 2000, 19–22 February, Bellevue, Washington; From Singular to Global Analyses of Biological Systems ABRF 1999, 19–22 March, Durham, North Carolina; Bioinformatics and Biomolecular Technologies: Linking Genomes, Proteomes and Biochemistry ABRF 1998, 21–24 March, San Diego, California; From Genomes to Function – Technical Challenges of the Post-Genome Era ABRF 1997, 9–12 February, Baltimore, Maryland; Techniques at the Genome-Proteome Interface ABRF 1996, 30 March – 2 April, San Francisco, California; Biomolecular Techniques
=== Cough === Codeine is used to relieve coughing. Evidence does not support its use for acute cough suppression in children. In Europe, it is not recommended as a cough medicine for those under 12 years of age. Some tentative evidence shows it can reduce a chronic cough in adults.
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.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.