batch purity raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-12-24 and is reviewed periodically as new material appears.
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.
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.
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.
| 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 |
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.
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
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.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
=== Pharmacokinetics === Topilutamide is a topical medication and is applied to the scalp. Topilutamide degrades in human serum at 37 °C with a half-life of approximately 6 hours and is undetectable after 48 hours. Perfluoroacylamido-arylpropanamides decompose hydrolytically to BP-34 and their corresponding perfluorocarboxylic acid. In the case of topilutamide, that perfluorocarboxylic acid is trifluoroacetic acid. The two metabolites of topilutamide namely BP-34 and trifluoroacetic acid were undetectable in human serum (below the detection limit of 5 ng/mL) along with the parent compound topilutamide, in human studies. BP-34 was shown to be devoid of anti-androgenic activity.
The influence of Nasser's Arab nationalism over the RCC was immediately apparent. The administration was instantly recognized by the neighbouring Arab nationalist regimes in Egypt, Syria, Iraq, and Sudan, with Egypt sending experts to aid the inexperienced RCC. Gaddafi propounded pan-Arab ideas, proclaiming the need for a single Arab state stretching across North Africa and the Middle East. In December 1969, Libya signed the Tripoli Charter alongside Egypt and Sudan. This established the Arab Revolutionary Front, a pan-national union designed as a first step towards the eventual political unification of the three nations. In 1970 Syria declared its intention to join. Nasser died unexpectedly in September 1970, with Gaddafi playing a prominent role at his funeral. Nasser was succeeded by Anwar Sadat, who replaced the idea of a unified state with a political federation, implemented in April 1971; in doing so, Egypt, Syria, and Sudan received large grants of Libyan oil money. In July 1971, Gaddafi sided with Sadat against the Soviet Union in the 1971 Sudanese coup d'état and dispatched Libyan fighter jets to force down a British Overseas Airways Corporation jetliner carrying the leading coup plotters, Farouk Osman Hamadallah and Babikir al-Nour. They were extradited back to Khartoum, where they were promptly executed by Sudanese leader Jaafar Nimeiry. In February 1972, Gaddafi and Sadat signed an unofficial charter of merger, but it was never implemented because relations broke down the next year.
The aqueous humour is a transparent water-like fluid similar to blood plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posterior chambers of the eye, and is not to be confused with the vitreous humour, which is located in the space between the lens and the retina, also known as the posterior cavity or vitreous chamber. Blood cannot normally enter the eyeball.
Florey was full of praise for their achievement, but disturbed that they had turned to the Americans for advice instead of him. "Am I not Australian?" he asked Keogh, "Have I not had some leading role in this thing?"
Sources: en.wikipedia.org
In 1969, Biden resumed practicing law, first as a public defender in Wilmington, Delaware. Most of his clients were African Americans from Wilmington's east side. Biden then joined a firm headed by Sid Balick, a locally active Democrat. Balick named him to the Democratic Forum, a group trying to reform and revitalize the state party, and Biden switched his registration to Democratic. He also started his own firm, Biden and Walsh. Corporate law, however, did not appeal to him, and criminal law did not pay well. He supplemented his income by managing properties. Biden ran for the fourth district seat on the New Castle County Council in 1970 on a liberal platform that included support for public housing in the suburbs. Biden won the general election, defeating Republican Lawrence T. Messick, and took office on January 5, 1971. He served until January 1, 1973. During his time on the county council, Biden opposed large highway projects, which he argued might disrupt Wilmington neighborhoods. Biden had not openly supported or opposed the Vietnam War until he ran for Senate and opposed Richard Nixon's conduct of the war. While studying at the University of Delaware and Syracuse University, Biden obtained five student draft deferments. Based on a physical examination, he was given a conditional medical deferment in 1968; in 2008, a spokesperson for Biden said his having had "asthma as a teenager" was the reason.
Liraglutide and semaglutide should not be used in those with a personal or family history of medullary type thyroid cancers as they may increase the risk of these types of tumors. Their use is further contraindicated in those with acute kidney injury, gallbladder disease or a history of pancreatitis. The FDA prescribing information for semaglutide recommends monitoring for depression or suicidal thoughts during treatment, though a real-world retrospective study of adolescents with obesity found that treatment with liraglutide or semaglutide was associated with a reduced risk for suicidal ideation or attempt. Setmelanotide is approved for children six years or older with certain types of secondary obesity. It may cause skin hyperpigmentation or other dermatologic effects as well as gastrointestinal side effects, with rare instances of depression and suicidal ideation. Metformin is often used off-label in children or adolescents with obesity, and has been found to cause a 1.1 decrease in BMI. A Cochrane review in 2016 concluded that medications might reduce BMI and bodyweight to a small extent in obese children and adolescents. This conclusion was based only on low-quality evidence.
=== Transplant === While dietary therapy has been shown to be effective to normalize the very-long chain fatty acid concentrations in the plasma of individuals with ALD, allogeneic hematopoietic stem cell transplants is the only treatment that can stop demyelination that is the hallmark of the cerebral forms of the disease. In order to be effective, the transplant must be done at an early stage of the disease; if the demyelination has progressed, transplant can worsen the outcome, and increase the rate of decline. While transplants have been shown to be effective at halting the demyelination process in those presenting with the childhood cerebral form of ALD, follow-up of these patients has shown that it does not improve adrenal function.
=== Vinylogous carboxylic acids === Normal carboxylic acids are the direct union of a carbonyl group and a hydroxyl group. In vinylogous carboxylic acids, a carbon-carbon double bond separates the carbonyl and hydroxyl groups.
This enzyme found in yeasts and humans converts D-ribosylnicotinate to nicotinate mononucleotide by transferring a phosphate group from the cofactor, adenosine triphosphate (ATP), which is converted to adenosine diphosphate (ADP). This is part of the biosynthetic pathway to nicotinamide adenine dinucleotide. An alternative substrate for the enzyme is nicotinamide riboside, similar to the enzyme ribosylnicotinamide kinase.
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.
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.