If you have been reading about reverse-phase HPLC 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.
Updated 2026-02-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| 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 |
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
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.
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.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
Most Indian shopping happens in open markets or numerous small grocery and retail shops. Shoppers typically wait outside the shop, ask for what they want, and can not pick or examine a product from the shelf. Access to the shelf or product storage area is limited. Once the shopper requests the food staple or household product they are looking for, the shopkeeper goes to the container or shelf or to the back of the store, brings it out and offers it for sale to the shopper. Often the shopkeeper may substitute the product, claiming that it is similar or equivalent to the product the consumer is asking for. The product typically has no price label in these small retail shops; all packaged products must display the maximum retail price (MRP) above which the product cannot be sold. It is a criminal offence to sell a product beyond the MRP of a product. The shopkeeper can price the food staple and household products arbitrarily, and two consumers may pay different prices for the same product on the same day but never will those price be above the maximum retail price. Price is rarely negotiated between the shopper and shopkeeper. The shoppers usually do not have time to examine the product label, and do not have a choice to make an informed decision between competitive products. India's retail and logistics industry, organised and unorganized in combination, employs about 40 million Indians (3.3% of Indian population). The typical Indian retail shops are very small.
=== Table II === acetone anthranilic acid diethyl ether hydrochloric acid (hydrogen chloride) methyl ethyl ketone piperidine sulphuric acid toluene The salts of the substances listed in this Table whenever the existence of such salts is possible. The salts of hydrochloric acid and sulphuric acid are specifically excluded from Table II.
Rheumatoid arthritis and other diseases that cause inflammation of the flexor tendons. With severe untreated hypothyroidism, generalized myxedema causes deposition of mucopolysaccharides within both the perineurium of the median nerve, as well as the tendons passing through the carpal tunnel. Association of CTS with lesser degrees of hypothyroidism is questioned. Pregnancy may bring out symptoms in genetically predisposed individuals, which may be caused by the temporary changes in hormones and fluids, which increase pressure in the carpal tunnel. High progesterone levels and water retention may increase the size of the synovium. Bleeding and swelling from a fracture or dislocation. This is referred to as acute carpal tunnel syndrome. Acromegaly causes excessive secretion of growth hormones. This causes the soft tissues and bones around the carpal tunnel to grow and compress the median nerve.
== A == Abidi alkyne synthesis Acetalisation Acetoacetic ester condensation Achmatowicz reaction Acylation Acyloin condensation Adams' catalyst Adams decarboxylation Adkins catalyst Adkins–Peterson reaction Akabori amino acid reaction Alcohol oxidation Alder ene reaction Alder–Stein rules Aldol addition Aldol condensation Algar–Flynn–Oyamada reaction Alkylimino-de-oxo-bisubstitution Alkyne trimerisation Alkyne zipper reaction Allan–Robinson reaction Allylic rearrangement Amadori rearrangement Amine alkylation Angeli–Rimini reaction Andrussov oxidation Appel reaction Arbuzov reaction, Arbusow reaction Arens–Van Dorp synthesis, Isler modification Aromatic nitration Arndt–Eistert synthesis Aston–Greenburg rearrangement Auwers synthesis Aza-Cope rearrangement Azo coupling
=== Immunity === The main immune cells active in the tissue are macrophages and neutrophils, although other leukocytes are also present. These work to phagocytize old or damaged tissue, and protect the healing tissue from pathogenic infection. This is necessary both to aid the healing process and to protect against invading pathogens, as the wound often does not have an effective skin barrier to act as a first line of defense.
Sources: en.wikipedia.org
==== Pancreatitis ==== The evidence suggesting a link between benzodiazepines (and Z-Drugs) and pancreatic inflammation is very sparse and limited to a few observational studies from Taiwan. A criticism of confounding can be applied to these findings as with the other controversial associations above. Further well-designed research from other populations, as well as a biologically plausible mechanism, is required to confirm this association.
He acknowledged that up to 200 Americans who wanted to leave did not, despite his August 18 pledge to keep troops in Afghanistan until all Americans who wanted to leave had left. After the withdrawal, the U.S. continued to send aid to Afghanistan, remaining its biggest aid donor as of August 2024 and spending at least $20.7 billion post-withdrawal. U.S. funding has helped support the Taliban government and stabilize Afghanistan's economy. On September 25, 2024, the United States House of Representatives passed a resolution condemning the Biden administration for the U.S. withdrawal from Afghanistan, with ten Democrats and all Republicans voting in favor.
== Until November 2022 == In June 2009, after being criticized by Kanye West and sued by Tony La Russa over unauthorized accounts run by impersonators, the company launched their "Verified Accounts" program. Twitter stated that an account with a "blue tick" verification badge indicates "we've been in contact with the person or entity the account is representing and verified that it is approved". After the beta period, the company stated in their FAQ that it "proactively verifies accounts on an ongoing basis to make it easier for users to find who they're looking for" and that they "do not accept requests for verification from the general public". Originally, Twitter took on the responsibility of reaching out to celebrities and other notable people to confirm their identities in order to establish a verified account. In July 2016, Twitter announced a public application process to grant verified status to an account "if it is determined to be of public interest" and that verification "does not imply an endorsement". In 2016, the company began accepting requests for verification, but it was discontinued the same year. Twitter explained that the volume of requests for verified accounts had exceeded its ability to cope; rather, Twitter determines on its own whom to approach about verified accounts, limiting verification to accounts which are "authentic, notable, and active". In November 2020, Twitter announced a relaunch of its verification system in 2021.
Pizza Hut was launched on May 31, 1958, by two brothers, Dan and Frank Carney, both Wichita State students, as a single location in Wichita, Kansas. They were given a $600 loan from their mother to start the business. The brothers used the name Pizza Hut because the sign could only hold eight letters. Six months later they opened a second outlet, and within a year they were operating six locations. The brothers began franchising in 1959 with a location in Topeka, Kansas. By 1963, there were 24 locations. One early employee was future Pro Football Hall of Fame head coach Bill Parcells, who had worked for the company while a college student and football player at Wichita State University. Parcells was considering a franchise for a career (as well as law school), but instead chose to enter coaching, eventually becoming a head coach in the National Football League. By 1966, the company had 140 locations and had established its headquarters in Wichita. The first Pizza Hut restaurant east of the Mississippi River was opened in Athens, Ohio, in 1966 by Lawrence Berberick and Gary Meyers. The iconic Pizza Hut building style with the distinctive red roof was introduced in 1969, and was later incorporated into the corporate logo. By the end of the decade, there were over 300 locations. The Carneys took the company public in 1969. By 1971, Pizza Hut had more locations and higher sales than any of its competitors. In the early 1970s, Pizza Hut opened several other chains to diversify its menu.
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.
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.