Everything below concerns lyophilized. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
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.
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.
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.
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.
=== Oliver and Schäfer (1894) === British physician George Oliver and physiologist Edward Albert Schäfer, professor at University College London, collaborated on the physiological effects of adrenal extracts. They first published their findings in two reports in 1894, a full publication followed in 1895. Though frequently falsely attributed to secretin, found in 1902 by Bayliss and Starling, Oliver and Schäfer's adrenal extract containing adrenaline, the substance causing the physiological changes, was the first hormone to be discovered. The term hormone would later be coined by Starling.
== Recommended levels == In setting human nutrient guidelines, government organizations do not necessarily agree on amounts needed to avoid deficiency or maximum amounts to avoid the risk of toxicity. For example, for vitamin C, recommended intakes range from 40 mg/day in India to 155 mg/day for the European Union. The table below shows U.S. Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins, PRIs for the European Union (same concept as RDAs), followed by what three government organizations deem to be the safe upper intake. RDAs are set higher than EARs to cover people with higher than average needs. Adequate Intakes (AIs) are set when there is not sufficient information to establish EARs and RDAs. Governments are slow to revise information of this nature. For the U.S. values, with the exception of calcium and vitamin D, all of the data date to 1997–2004. All values are consumption per day:
The two substrates of this enzyme are L-histidinol and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are L-histidine, reduced NADH, and two protons. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-histidinol:NAD+ oxidoreductase. This enzyme is also called L-histidinol dehydrogenase.
== The Strep-tag principle == Just like other short-affinity tags (His-tag, FLAG-tag), the Strep-tag can be easily fused to recombinant proteins during subcloning of its cDNA or gene. For its expression, various vectors for various host organisms (E. coli, yeast, insect, and mammalian cells) are available. A particular benefit of the Strep-tag is its rather small size and the fact that it is biochemically almost inert. Therefore, protein folding or secretion is not influenced and usually it does not interfere with protein function. Strep-tag is especially suited for analysis of functional proteins, because the purification procedure can be kept under physiological conditions. This not only allows the isolation of sensitive proteins in a native state, but it is also possible to purify intact protein complexes, even if just one subunit carries the tag. In the first step of the Strep-tag purification cycle, the cell lysate containing Strep-tag fusion protein is applied to a column with immobilized Strep-Tactin (step 1). After the tagged protein has specifically bound to Strep-Tactin, a short washing step with a physiological buffer (e.g. phosphate buffered saline, PBS) removes all other host proteins (step 2). This is due to Strep-Tactin's low tendency to bind proteins non specifically. Then, the purified Strep-tag fusion protein is gently eluted with a low concentration of desthiobiotin, which specifically competes for the biotin binding pocket (step 3). To regenerate the column, desthiobiotin is removed by application of a HABA containing solution (a yellow azo dye).
=== Natural === Biological systems often feature natural, functional nanomaterials. The structure of foraminifera (mainly chalk) and viruses (protein, capsid), the wax crystals covering a lotus or nasturtium leaf, spider and spider-mite silk, the blue hue of tarantulas, the "spatulae" on the bottom of gecko feet, some butterfly wing scales, natural colloids (milk, blood), horny materials (skin, claws, beaks, feathers, horns, hair), paper, cotton, nacre, corals, and even our own bone matrix are all natural organic nanomaterials. Natural inorganic nanomaterials occur through crystal growth in the diverse chemical conditions of the Earth's crust. For example, clays display complex nanostructures due to anisotropy of their underlying crystal structure, and volcanic activity can give rise to opals, which are an instance of naturally occurring photonic crystals due to their nanoscale structure. Fires represent particularly complex reactions and can produce pigments, cement, fumed silica etc. Natural sources of nanoparticles include combustion products forest fires, volcanic ash, ocean spray, and the radioactive decay of radon gas. Natural nanomaterials can also be formed through weathering processes of metal- or anion-containing rocks, as well as at acid mine drainage sites.
Sources: en.wikipedia.org
16 November – The SNP's National Executive Committee proposes cutting the number of staff at its headquarters from 26 to 16. Ruth Maguire, MSP for Cunninghame South, announces she will not seek re-election at the 2026 Scottish Parliament election because she is to undergo treatment for cancer. 17 November – At 12pm, Tesco opens its branch in Stornaway, Isle of Lewis for the first time on a Sunday, the Western Isles being the only place in the UK where the majority of shops remain closed on a Sunday. 19 November – Scottish Labour leader Anas Sarwar says his party will expand the eligibility for winter fuel payments in Scotland if they win the 2026 Scottish Parliament election. Eric Trump, the son of Donald Trump, confirms the US President-elect will visit Scotland in 2025 to open a new golf course. The Scottish Government is reported to be preparing to reduce the minimum term served by prisoners given short sentences, which could lead to the early release of between 260 and 390 prisoners in February 2025. 20 November – The Children and Young People's Commissioner Scotland launches an investigation into Police Scotland's use of force against children. 21 November – Stephen Flynn, the SNP's leader at Westminster, says he will not seek a dual mandate by standing for the Scottish Parliament while he remains an MP. Traditional Scottish singer Iona Fyfe is named as the new Rector of the University of Aberdeen, succeeding Martina Chukwuma–Ezike, and will take up the post on 1 January 2025.
=== Pharmacodynamics === Compared to propofol, ciprofol exhibits stronger binding to the GABAA receptor and elicits a greater enhancement of GABAA receptor-mediated neurotransmission. It also acts as a SIRT1 activator. Ciprofol exhibits pharmacodynamic properties similar to those of propofol, including both rapid onset and rapid offset. Ciprofol appears to have similar effects upon the respiratory and cardiovascular systems as those propofol.
=== Approvals === Lupron injection was approved by the FDA for treatment of advanced prostate cancer on 9 April 1985. Lupron depot for monthly intramuscular injection was approved by the FDA for palliative treatment of advanced prostate cancer on 26 January 1989. Viadur was approved by the FDA for palliative treatment of advanced prostate cancer on 6 March 2000. Eligard was approved by the FDA for palliative treatment of advanced prostate cancer on 24 January 2002. Fensolvi was approved by the FDA for children with central precocious puberty on 4 May 2020.
hydrophilic Soluble in or having an affinity for water or other polar compounds; describing a polar molecule, or a moiety or functional group within a molecule, which participates in intermolecular interactions such as hydrogen bonding with other polar molecules and therefore readily dissolves in polar solvents such as water or aqueous solutions. Unlike hydrophobic compounds, hydrophilic compounds can form energetically favorable contacts with the aqueous phase of biological fluids and so can often be suspended directly in the cytosol or exposed to extracellular spaces. Together, the contrasting properties of hydrophilicity and hydrophobicity play major roles in determining the structural conformations and functions of most biomolecules.
Sources: en.wikipedia.org
=== Breast cancer === Keratin constitutes a large multigene family known as cytokeratins. These cytokeratins are differentially expressed across various epithelial types and have been extensively studied as markers for breast cancer. They are categorized into acidic type I and basic-to-neutral type II cytokeratins. The intermediate filament network is formed by the necessary pairing of equal amounts of type I and type II keratins. While hair keratins, such as KRT81, are typical in hard-keratinized structures like hair and nails, they are thought to serve as structural proteins specific to these organs without expression elsewhere, such as the mammary gland. KRT81, a type II hair keratin, is a major hair protein expressed in the hair cortex. Despite being typically associated with hair structures, KRT81 expression has been observed in the SKBR3 human breast cancer cell line and metastatic lymph nodes of breast carcinomas, but not in normal breast epithelial cells. Moreover, the expressed KRT81 was found to be a 5′-truncated isoform (ΔHb1), with the full-length protein not being expressed. However, the exact function of this truncated form in breast cancer cells remains unclear. Western blot analysis detected the presence of the complete 55-kDa KRT81 in various human breast cancer cell lines (MCF7, SKBR3, MDA-MB-231), normal human mammary epithelial cells (HMEC), and non-neoplastic cells (MCF10A). Reverse transcription-polymerase chain reaction confirmed the expression of the full-length KRT81, encompassing its 5' region, in breast cells.
=== Prostate cancer === Anti-androgens such as enzalutamide can be used as a treatment for prostate cancer, which, by binding to the androgen receptor, can inhibit the binding of testosterone. Androgens may promote prostate cancer, with the main androgens secreted by the testicles being testosterone and dihydroxytestosterone (DHT). Some androgens can be made by the adrenal glands, which are located above the kidneys. Abiraterone Acetate may also act as a hormone antagonist of androgens through its action as a CYP17 inhibitor. Abarelix, a GnRH antagonist may also be used for the treatment of prostate cancer.
=== May === 2 May – The 5% pay increase for one million NHS staff in England is signed off at a meeting between the UK government and representatives from 14 trade unions; all NHS employees but doctors and dentists are represented at the meeting. 5 May – Following her trial and conviction at Norwich Crown Court, Helen Hewlett is sentenced to seven and a half years in prison after attempting to hire a hitman to kill a colleague with whom she had a brief affair. 8 May – Data published by NHS Business Services Authority indicated the number of community pharmacies in England is at its lowest since 2015, with 1,025 pharmacies in operation, and 160 having closed in the past two years. 9 May – Several areas of England are hit by flash floods as much of the country is affected by heavy rain storms. 10 May – A major incident is declared in Somerset following heavy rain and flash flooding in southern England. The Metropolitan Police apologises for failing to disclose documents relating to the Murder of Daniel Morgan that were found in a locked cabinet at its headquarters. 12 May – David Boyd, 55, is found guilty at Newcastle Law Courts of the 1992 murder of Nikki Allan in Sunderland, Tyne and Wear. The jury of 10 women and two men spent two and a half hours of deliberating to convict Boyd of the murder. Boyd is due to be sentenced on 23 May 2023. 14 May – Chelsea defeat Manchester United 1–0 to win the 2023 Women's FA Cup final.
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.