If you have been reading about pharmacokinetics and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-03-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
BCN, also known as bicyclo[6.1.0]non-4-yne, is a copper-free click chemistry probe that enables highly efficient and completely orthogonal bioconjugation to complex macromolecules including peptides, nucleic acids and proteins, including monoclonal antibodies. The most recent and powerful application of this technology has been in the field of antibody-drug conjugates which results in targeted cancer therapeutics that have an improved therapeutic index, meaning they are more effective and better tolerated. BCN is well-suited for aqueous bioconjugations due to its high reactivity with its azide counterpart and its high hydrophilicity, relative to other metal-free click chemistry probes.
Dyspnea (shortness of breath) exacerbated by exertion Cough, often persistent and sometimes severe Fatigue Tachypnea (rapid breathing) which is often labored Loss of appetite and weight loss Chest pain Fever Gradual darkening of skin (blue skin) Gradual dark shallow rifts in nails eventually leading to cracks as protein fibers within nail beds are destroyed In advanced cases, the following may also occur:
=== Education === Platt attended a progressive boarding school named Colorado Rocky Mountain School in Carbondale, Colorado. Platt majored in drama at Tufts University, where he met and became close friends with Hank Azaria. He spent three years working in theatre in Boston, Massachusetts, which he said had a "wealth of serious amateur theatre at that time…I played many roles, and it was the best training I could have had." Platt travelled with Shakespeare and Company, based in Lenox, Massachusetts, touring schools to earn his Equity card, before moving to New York. Platt's early career involved Off-Broadway and regional theatre, and he appeared onstage with the New York Shakespeare Festival, Lincoln Center Theater, Manhattan Theatre Club and other companies across many genres. He obtained an agent while working at Manhattan Punch Line Theatre, and met actor Bill Murray at his cousin's Christmas party. Murray attended Platt's show and recommended Platt to director Jonathan Demme, who cast him in Married to the Mob in 1988. Platt attributes his breakthrough to appearing at the Punch Line Theater.
Stuart Hall (born 1929), a TV presenter convicted of indecent assault, lived in Wilmslow from 1958 to 2013 William Roache (born 1932) actor, plays Ken Barlow in Coronation Street since 1960; he has lived in Wilmslow for most of his adult life John Waite (born 1951), a presenter on British radio and TV, attended Wilmslow High School Barbara Wilshere (born 1959), an actress appearing in theatre, films and on TV, attended Wilmslow High School Jo Wheeler (born 1963), weather forecaster for Sky News, attended Wilmslow High School Fionnuala Ellwood (born 1964), an actress, portrayed Lynn Whiteley in the ITV soap Emmerdale, attended Wilmslow High School Miranda Sawyer (born 1967), journalist and broadcaster, and her brother Toby (born 1969), actor, grew up locally Chris Hawkins (born 1975), presenter and journalist, and his wife Clare Nasir (born 1970), meteorologist, have lived locally since 2012 Simon Gregson (born 1974), actor who plays taxi boss Steve McDonald in Coronation Street Ashley Taylor Dawson (born 1982), actor and singer, plays Darren Osborne in the Channel 4 soap opera Hollyoaks.
Sources: en.wikipedia.org
Plant hormones (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, including embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones. Went and Thimann coined the term "phytohormone" and used it in the title of their 1937 book. Phytohormones occur across the plant kingdom, and even in algae, where they have similar functions to those seen in vascular plants ("higher plants"). Some phytohormones also occur in microorganisms, such as unicellular fungi and bacteria, however in these cases they do not play a hormonal role and can better be regarded as secondary metabolites.
As a compromise with internationalist critics, the Big Four nations became the permanent members of the UN Security Council, with significantly less power than had been envisioned in the Four Policemen proposal. When the United Nations was officially established later in 1945, France was in due course added as the fifth permanent member of the Security Council because of the insistence of Churchill.
Although sodium-dependent transporters for vitamin C exists, it is present mainly in specialized cells whereas the glucose transporters, most notably GLUT1, transport DHA in most cells, where recycling back to ascorbic acid generates the necessary enzyme cofactor and intracellular antioxidant, (see Transport to mitochondria). The structure shown here for DHA is the commonly shown textbook structure. This 1,2,3-tricarbonyl is too electrophilic to survive more than a few milliseconds in aqueous solution, however. The actual structure shown by spectroscopic studies is the result of rapid hemiketal formation between the 6-OH and the 3-carbonyl groups. Hydration of the 2-carbonyl is also observed. The lifetime of the stabilized species is commonly said to be about 6 minutes under biological conditions. Destruction results from irreversible hydrolysis of the lactone bond, with additional degradation reactions following. Crystallization of solutions of DHA gives a pentacyclic dimer structure of indefinite stability. Recycling of vitamin C via active transport of DHA into cells, followed by reduction and reuse, mitigates the inability of humans to synthesize it from glucose.
=== Factors affecting production === The effects of carbon, nitrogen sources, and amino acids on growth and tabtoxin production by pv. tabaci were examined by varying the components of a defined basal medium, which contained the following nutrients per liter: sucrose (10 g), KNO3 (5 g), MgSO4·7H2O (0.2 g), CaCl2·2H2O (0.11 g), FeSO4·7H2O (20 mg), NaH2PO4·2H2O (0.9 g) and H2PO4·3H2O (1 g). Both growth and quantity of tabtoxin synthesized were significantly affected by carbon source, nitrogen source, and amino acid supplements. Sorbitol, xylose, and sucrose proved to be the best carbon sources for tabtoxin production. Specific toxin production was very low using glucose as a single carbohydrate source, although bacterial growth was well supported by glucose. Amount and type of nitrogen sources (NH4Cl or KNO3) affected the growth of pv. tabaci and quantities of tabtoxin produced. Nitrate is the best of these two forms of nitrogen for production of tabtoxin. Some progress has been made on elucidating factors that regulate tabtoxin biosynthesis in P. syringae.
Alice in Chains released its debut album Facelift on August 21, 1990, shaping the band's signature style. The second single, "Man in the Box", with lyrics written by Staley, became a huge hit. "Man in the Box" is widely recognized for its distinctive "wordless opening melody, where Staley's peculiar, tensed-throat vocals are matched in unison with an effects-laden guitar" followed by "portentous lines like: 'Jesus Christ / Deny your maker' and 'He who tries / Will be wasted' with Cantrell's drier, and less-urgent voice." Facelift has since been certified double platinum by the RIAA for sales of two million copies in the United States. The band toured in support of the album for two years before releasing the acoustic EP Sap in early 1992. Alice in Chains made a cameo in Cameron Crowe's 1992 film Singles, performing the songs "It Ain't Like That" and "Would?" In September 1992, Alice in Chains released Dirt. The critically acclaimed album, also the band's most successful, debuted at number six on the Billboard 200, and was certified quadruple platinum. Staley designed the sun logo on the album's inlay. During the Dirt tour in Brazil in 1993, Staley saved Starr's life after he had overdosed. Because of Staley's drug addiction, the band did not tour in support of Dirt for very long. Cantrell wrote almost all of the music and lyrics for Alice in Chains, but as time went on, Staley contributed more lyrics. Eventually, Staley would receive credit for about half the lyrics from the entire Alice in Chains catalog prior to the release of Black Gives Way to Blue in 2009.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.