A practical reference on batch purity: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-08-23 and is reviewed periodically as new material appears.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
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.
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.
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.
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.
==== US reactions ==== The Soviet success raised a great deal of concern in the United States. For example, economist Bernard Baruch wrote in an open letter titled "The Lessons of Defeat" to the New York Herald Tribune: "While we devote our industrial and technological power to producing new model automobiles and more gadgets, the Soviet Union is conquering space. ... It is Russia, not the United States, who has had the imagination to hitch its wagon to the stars and the skill to reach for the moon and all but grasp it. America is worried. It should be." Eisenhower ordered project Vanguard to move up its timetable and launch its satellite much sooner than originally planned. The December 6, 1957 Project Vanguard launch failure occurred at Cape Canaveral Air Force Station in Florida. It was a monumental failure, exploding a few seconds after launch, and it became an international joke. The satellite appeared in newspapers under the names Flopnik, Stayputnik, Kaputnik, and Dudnik. In the United Nations, the Soviet delegate offered the US representative aid "under the Soviet program of technical assistance to backwards nations." Only in the wake of this very public failure did von Braun's Redstone team get the go-ahead to launch their Jupiter-C rocket as soon as they could. In Britain, the US's Western Cold War ally, the reaction was mixed: some celebrated the fact that the Soviets had reached space first, while others feared the destructive potential that military uses of spacecraft might bring.
Some of the earliest ancient human civilisations in South Asia originated from areas encompassing present-day Pakistan. The earliest known stone tools in the region, dating to the Lower Palaeolithic (~2 million years ago), were discovered in the Soan Valley of northern Pakistan. The Indus plain region, which covers most of the present-day Pakistan, was the site of several successive ancient cultures including the Neolithic (7000–4300 BCE) site of Mehrgarh, and the 5,000-year history of urban life in South Asia to the various sites of the Indus Valley Civilisation, including Mohenjo-daro and Harappa. Following the decline of the Indus Valley Civilisation, semi-nomadic Indo-European Aryans migrated into the Indian subcontinent around 2000 BCE, perhaps by way of the Khyber Pass. They fused with the indigenous Harappan culture of the Indus Valley, and elements of the pre-Aryan spiritual traditions were assimilated into the developing Vedic tradition. This cultural milieu shaped the Gandhara Civilisation, which flourished at the crossroads of India, Central Asia, and the Middle East, connecting trade routes and absorbing cultural influences from diverse civilisations. By the early Vedic period, parts of the Indus region in present-day Pakistan were populated by numerous tribes that were beginning to coalesce into chieftain-led clans and early kingdoms. During this period, the Vedas, the oldest scriptures of Hinduism, were composed.
== Current status == Many exogenous agents have been developed since the discovery of 5-HT2C receptors. Thus far a small number of agonists, with sufficient selectivity for the 5-HT2C receptors over the other subtypes have been studied in clinical trials. A variety of other 5-HT2C receptor agonists remain in preclinical development, including Ro60-0175, WAY-163,909, and the inverse agonist SB-243,213. Evidence supports a therapeutic potential of 5-HT2C receptor modulation in the treatment of a variety of pathological conditions, including schizophrenia, obesity, urinary incontinence and sexual dysfunction.
Towards the end of the 16th century, pessaries became more common in the management of uterine prolapse, due in part to advances in anatomic knowledge of the female genitourinary tract earlier in the century. Pessaries were usually made out of wax, metal, glass, or wood. Charles Goodyear's invention of volcanized rubber in the mid-1800s made it possible to produce pessaries that would not decompose. However, even into the 1800s, alternative practices were still used, such as the use of sea-water douches, postural exercises, and leeching. Although the use of surgery in the treatment of uterine prolapse had been described previously, the 19th century saw advances in surgical techniques. During the mid to late 1800s, surgical attempts to manage uterine prolapse included narrowing the vaginal vault, suturing the perineum, and amputating the cervix. In 1877, LeFort described the process of a partial colpocleisis. In 1861, Choppin in New Orleans reported the first instance in which vaginal hysterectomy was performed for uterine prolapse. Prior to that, vaginal hysterectomies were mainly performed for malignancies. Following Alwin Mackenrodt's 1895 publication of a comprehensive description of the female pelvic floor connective tissue, Fothergill began working on the Manchester-Fothergill surgery with the belief that the cardinal and uterosacral ligaments were key support structures for the uterus. In 1907, Josef Haban and Julius Tandler theorized that the levator ani muscles were also very important for uterine support.
In the summer of 1793 the sans-culottes, the Parisian enragés especially, accused even the most radical Jacobins of being too tolerant of greed and insufficiently universalist. From this far-left point of view, all Jacobins were at fault because all of them tolerated existing civil life and social structures. The sans-culottes also populated the ranks of paramilitary forces charged with physically enforcing the policies and legislation of the revolutionary government, a task that commonly included violence and the carrying out of executions against perceived enemies of the revolution. During the peak of their influence, the sans-culottes were seen as the truest and most authentic sons of the French Revolution, held up as living representations of the revolutionary spirit. During the height of revolutionary fervor, such as during the Reign of Terror when it was dangerous to be associated with anything counter-revolutionary, even public functionaries and officials actually from middle or upper-class backgrounds adopted the clothing and label of the sans-culottes as a demonstration of solidarity with the working class and patriotism for the new French Republic. But by early 1794, as the bourgeois and middle-class elements of the revolution began to gain more political influence, the fervent working-class radicalism of the sans-culottes rapidly began falling out of favour within the National Convention.
Sources: en.wikipedia.org
Many other species worldwide within the family Muricidae, for example Plicopurpura pansa, from the tropical eastern Pacific, and Plicopurpura patula from the Caribbean zone of the western Atlantic, can also produce a similar substance (which turns into an enduring purple dye when exposed to sunlight) and this ability has sometimes also been historically exploited by local inhabitants in the areas where these snails occur. (Some other predatory gastropods, such as some wentletraps in the family Epitoniidae, seem to also produce a similar substance, although this has not been studied or exploited commercially.) The dog whelk Nucella lapillus, from the North Atlantic, can also be used to produce red-purple and violet dyes.
Another factor affecting the treatment response is the generation of antibodies against the infused enzyme, which is particularly severe in Pompe infants who have a complete deficiency of the acid alpha-glucosidase. Immune tolerance therapy to eliminate these antibodies has improved the treatment outcome. A Late Onset Treatment Study (LOTS) was published in 2010. The study was undertaken to evaluate the safety and efficacy of aglucosidase alfa in juvenile and adult patients with Pompe disease. LOTS was a randomized, double-blind, placebo-controlled study that enrolled 90 patients at eight primary sites in the United States and Europe. Participants received either aglucosidase alfa or a placebo every other week for 18 months. The average age of study participants was 44 years. The primary efficacy endpoints of the study sought to determine the effect of Myozyme on functional endurance as measured by the six-minute walk test and to determine the effect of aglucosidase alfa on pulmonary function as measured by percent predicted forced vital capacity. The results showed that, at 78 weeks, patients treated with aglucosidase alfa increased their distance walked in six minutes by an average of approximately 25 meters as compared with the placebo group which declined by 3 meters (P=0.03). The placebo group did not show any improvement from baseline. The average baseline distance walked in six minutes in both groups was approximately 325 meters. Percent predicted forced vital capacity in the group of patients treated with aglucosidase alfa increased by 1.2 percent at 78 weeks.
==== 8 April ==== In Iran, the Lavan Oil Refinery, located on Lavan Island was struck at around 10 a.m.; a fire ignited. The Iranian authorities denounced the event and stated that it was an act of "cowardice" by the "enemies". Israel denied being involved in the attack. The debris of a drone shot down by Iranian forces killed a 7-year-old child and injured another six members of the child's family in the town of Shushtar in Khuzestan province.
Based on their interpretation of scriptures such as Acts 15:28, 29 ("Keep abstaining...from blood."), many Jehovah's Witnesses neither consume blood nor accept transfusions of whole blood or its major components: red blood cells, white blood cells, platelets (thrombocytes), and plasma. Members may personally decide whether they will accept medical procedures that involve their own blood or substances that are further fractionated from the four major components.
where the ion AB+ collides with the neutral species M and subsequently breaks apart. The details of this process are described by collision theory. Due to different instrumental configuration, two main different types of CID are possible: (i) beam-type (in which precursor ions are fragmented on-the-flight) and (ii) ion trap-type (in which precursor ions are first trapped, and then fragmented). A third and more recent type of CID fragmentation is higher-energy collisional dissociation (HCD). HCD is a CID technique specific to orbitrap mass spectrometers in which fragmentation takes place external to the ion trap, it happens in the HCD cell (in some instruments named "ion routing multipole"). HCD is a trap-type fragmentation that has been shown to have beam-type characteristics. Freely available large scale high resolution tandem mass spectrometry databases exist (e.g. METLIN with 960,000 molecular standards each with experimental CID MS/MS data), and are typically used to facilitate small molecule identification.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.