The short version of RP-HPLC purity fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-03 and is reviewed periodically as new material appears.
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
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.
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.
However, the Whig-Radical amalgam could not become a true modern political party while it was dominated by aristocrats and it was not until the departure of the "Two Terrible Old Men", Russell and Palmerston, that Gladstone could become the first leader of the modern Liberal Party. This was brought about by Palmerston's death in 1865 and Russell's retirement in 1868. After a brief Conservative government (during which the Second Reform Act was passed by agreement between the parties), Gladstone won a huge victory at the 1868 election and formed the first Liberal government. The establishment of the party as a national membership organisation came with the foundation of the National Liberal Federation in 1877. The philosopher John Stuart Mill was also a Liberal MP from 1865 to 1868.
Eyes: Chronic conjunctivitis, scars on cornea, corneal opacities, early cataracts Respiratory tracts: Obstructive and/or restrictive disease, pulmonary fibrosis, aggravation of tuberculosis and chronic bronchitis Neurological system: Impairment of memory, finer motor skills, numbness, etc. Psychological problems: Post traumatic stress disorder (PTSD) Children's health: Peri- and neonatal death rates increased. Failure to grow, intellectual impairment, etc. Missing or insufficient fields for research are female reproduction, chromosomal aberrations, cancer, immune deficiency, neurological sequelae, post traumatic stress disorder (PTSD) and children born after the disaster. Late cases that might never be highlighted are respiratory insufficiency, cardiac insufficiency (cor pulmonale), cancer and tuberculosis. Bhopal now has high rates of birth defects and records a miscarriage rate 7x higher than the national average. A 2014 report in Mother Jones quotes a "spokesperson for the Bhopal Medical Appeal, which runs free health clinics for survivors" as saying "An estimated 120,000 to 150,000 survivors still struggle with serious medical conditions including nerve damage, growth problems, gynaecological disorders, respiratory issues, birth defects, and elevated rates of cancer and tuberculosis."
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in numerous biological pathways, including digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life including viruses. They have independently evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms.
Sources: en.wikipedia.org
== Pharmacology == Computer models suggest fentanyl binds to μ-opioid receptors in its protonated form. Fluorination of fentanyl at the 3-position lowers the pKa of its conjugate acid from 8.4 to 6.8, a change designed to reduce its systemic effects while maintaining its potency in inflamed tissue, as this is a more acidic environment (pH 5–7) than non-inflamed tissue (pH 7.4). In experiments on rats with different types of inflammatory pain, it has been shown that NFEPP produces injury-restricted analgesia, while exhibiting reduced typical opiate effects such as respiratory depression, sedation, constipation, and chemical seeking behavior. As a result, NFEPP has the potential to reduce opioid addiction and dependency, as there is no effect on users who are not actually suffering from pain, as the chemical does not interact with non-inflamed brain tissue until much higher doses are reached. Further research indicates other fluorinated derivatives of fentanyl, such as β-fluorofentanyl (FF3) or 2'-fluoro β-fluorofentanyl (RR-49), may be more effective in achieving high potency in damaged tissue with low potency in undamaged tissue.
=== John-Daniel Stern === John-Daniel "JD" Stern (Adain Bradley) is Harper's estranged twin brother, who disappeared from her life when the two were teenagers. In series 2, Harper tracks down her brother to Berlin, where he works as a line cook. The two spend the night at a club, and the next morning, JD relapses on his meth addiction. The two have a vicious argument over their childhood growing up with an abusive mother; JD reveals he ran away in part due to Harper exacerbating the pressure their mother put on him to be a star tennis player, but Harper maintains that she too escaped a traumatic upbringing. Harper begs JD to come home with her, but rebuffs her, branding his sister a selfish narcissist who was complicit in the abuse he suffered. Harper is left deeply shaken by the encounter. In series 4, JD calls Harper to tell her that their mother died in a freak accident, having fallen down the stairs while collecting an Amazon delivery. Harper struggles to grieve her mother's death given her traumatic childhood, as well as her preoccupation with her work.
== Early life == Nayib Armando Bukele Ortez was born on 24 July 1981 in San Salvador, El Salvador. His father was Armando Bukele Kattán, a businessman and industrial chemist, and his mother is Olga Marina Ortez. Bukele's father died in 2015. Bukele was the couple's first child. He has three younger brothers, Karim, Yusef, and Ibrajim, and has four paternal half-sisters and two paternal half-brothers. Bukele's father converted from Christianity to Islam in the 1980s, became an imam, and founded four mosques in El Salvador. Bukele's mother is Catholic. Bukele's paternal grandparents were Palestinian Christians who emigrated to El Salvador from Jerusalem and Bethlehem in 1921. His maternal grandfather was Greek Orthodox, and his maternal grandmother was Catholic. Bukele completed his secondary education at the Escuela Panamericana in 1999 at age 18. Bukele enrolled at Central American University in San Salvador to study legal sciences, aspiring to become a lawyer, but dropped out to work for the Nölck advertising agency, one of his father's businesses. Nölck campaigned for the Farabundo Martí National Liberation Front (FMLN), a left-wing Salvadoran political party. In 1999, Bukele founded the marketing company Obermet, also known as 4am Saatchi & Saatchi El Salvador, and was its president from 1999 to 2006 and from 2010 to 2012. The company ran political advertising for the FMLN presidential campaigns of Schafik Hándal in 2004 and Mauricio Funes in 2009.
The United States Department of Defense asks the US defense sector to accelerate the manufacturing and delivery of armaments, including ammunition that is in short supply because of the 2026 Iran war. Royce White becomes the second former NBA player, after Enes Kanter Freedom, to declare that they are eligible for the 2027 WNBA draft. August 9 – 2026 cyclosporiasis outbreak, salmonellosis in the United States: Taylor Farms extends its recalls to products containing jalapeños after they were linked to the ongoing salmonellosis outbreak in the United States. Taylor Farms currently has a recall for iceberg lettuce linked to cyclosporiasis. August 10 Staff secretary Will Scharf is named as White House counsel by Trump. Trump states that he instructed US negotiators to demand reparations from the Iranian regime for Americans it has killed and seriously injured in conflicts, as well as the families of protesters who were slain in Iran, falsely claiming that it was involved in the attack on the USS Cole. Trump also states that the regime should be held accountable for damages and deaths inflicted on Lebanese, Palestinian, Syrian, and Yemeni civilians. August 11 Democratic senators Richard Blumenthal and Adam Schiff investigate the alleged coordination between ICE and the Iranian regime to deport detainees. US rights organizations sue Trump over sanctions against the ICC. August 12 A Pentagon assessment finds that US strikes targeting the Houthis killed 153 civilians in Yemen over the past year.
Sources: en.wikipedia.org
==== War poetry ==== Thomas's horror of war, foreshadowed in some of his poems of the 1930s and fuelled by his lived experience of the bombing raids and fire storms of the Blitz in London, received further expression in his poems of the war period. These include elegies for an elderly man—Among Those Killed in a Dawn Raid Was a Man Aged a Hundred (1941)—and for child victims of incendiary bombing raids in Ceremony After a Fire Raid (1944) and A Refusal to Mourn the Death, by Fire, of a Child in London (1945). They were collected in Deaths and Entrances, the fourth volume of his poetry, published in 1946. The sentiments expressed in his war poems were, according to Walford Davies, representative of "the real temper of the British people of the time—the resilience and the guts".
== Chemical properties == Trisulfuryl fluoride is a reactive compound. It is known to decompose into disulfuryl fluoride when heated. The compound reacts with certain compounds, like the sodium cyanohydrin salt, to form other fluorosulfates. It slowly hydrolizes in the solution of potassium hydroxide (KOH):
Fluorescent reporter probes detect only the DNA containing the sequence complementary to the probe; therefore, use of the reporter probe significantly increases specificity, and enables performing the technique even in the presence of other dsDNA. Using different-coloured labels, fluorescent probes can be used in multiplex assays for monitoring several target sequences in the same tube. The specificity of fluorescent reporter probes also prevents interference of measurements caused by primer dimers, which are undesirable potential by-products in PCR. However, fluorescent reporter probes do not prevent the inhibitory effect of the primer dimers, which may depress accumulation of the desired products in the reaction. The method relies on a DNA-based probe with a fluorescent reporter at one end and a quencher of fluorescence at the opposite end of the probe. The close proximity of the reporter to the quencher prevents detection of its fluorescence; breakdown of the probe by the 5' to 3' exonuclease activity of the Taq polymerase breaks the reporter-quencher proximity and thus allows unquenched emission of fluorescence, which can be detected after excitation with a laser. An increase in the product targeted by the reporter probe at each PCR cycle therefore causes a proportional increase in fluorescence due to the breakdown of the probe and release of the reporter.
Sources: en.wikipedia.org
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.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.