If you have been reading about heptapeptide 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 2026-03-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
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.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
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.
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.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
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.
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.
Iron-deficiency anemia is anemia caused by a lack of iron. Anemia is defined as a decrease in the number of red blood cells or the amount of hemoglobin in the blood. When onset is slow, symptoms are often vague, such as feeling tired, weak, short of breath, or having decreased ability to exercise. Anemia that comes on quickly often has more severe symptoms, including confusion, feeling like one is going to pass out or increased thirst. Anemia is typically significant before a person becomes noticeably pale. Children with iron deficiency anemia may have problems with growth and development. There may be additional symptoms depending on the underlying cause. Iron-deficiency anemia is caused by blood loss, insufficient dietary intake, or poor absorption of iron from food. Sources of blood loss can include heavy periods, childbirth, uterine fibroids, stomach ulcers, colon cancer, and urinary tract bleeding. Poor absorption of iron from food may occur as a result of an intestinal disorder such as inflammatory bowel disease or celiac disease, or surgery such as a gastric bypass. In the developing world, parasitic worms, malaria, and HIV/AIDS increase the risk of iron deficiency anemia. Diagnosis is confirmed by blood tests. Iron deficiency anemia can be prevented by eating a diet containing sufficient amounts of iron or by iron supplementation. Foods high in iron include meat, nuts, and foods made with iron-fortified flour.
The Space Race (Russian: космическая гонка, romanized: kosmicheskaya gonka, IPA: [kɐsˈmʲitɕɪskəjə ˈɡonkə]) was a 20th-century competition between the Cold War rivals, the United States and the Soviet Union, to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the two nations that followed World War II and the onset of the Cold War. The technological advantage demonstrated by spaceflight achievement was seen as necessary for national security, particularly in regard to intercontinental ballistic missile and satellite reconnaissance capability, but also became part of the cultural symbolism and ideology of the time. The Space Race brought pioneering launches of artificial satellites, robotic landers to the Moon, Venus, and Mars, and human spaceflight in low Earth orbit and ultimately to the Moon. Public interest in space travel originated in the 1951 publication of a Soviet youth magazine and was promptly picked up by US magazines. The competition began on July 29, 1955, when the United States announced its intent to launch artificial satellites for the International Geophysical Year. Five days later, the Soviet Union responded by declaring they would also launch a satellite "in the near future". The launching of satellites was enabled by developments in ballistic missile capabilities since the end of World War II. The competition gained Western public attention with the "Sputnik crisis", when the USSR achieved the first successful satellite launch, Sputnik 1, on October 4, 1957.
Pakistan is a member of the United Nations, the Shanghai Cooperation Organisation, the Organisation of Islamic Cooperation, the Commonwealth of Nations, the South Asian Association for Regional Cooperation, and the Islamic Military Counter-Terrorism Coalition, and is designated as a major non-NATO ally by the United States.
== Pharmacology == Epelsiban was investigated for a potential role in benign prostatic hyperplasia also called prostate enlargement. Oxytocin treatment induces prostate enlargement in mice and produces contractions of the prostate through its specific receptor. Oxytocin concentrations are elevated in prostatic tissue from patients with benign prostatic hyperplasia. Epelsiban was found to inhibit the contractile effect of oxytocin in human prostatic tissue through its specific oxytocin receptors in a concentration-dependent manner. suggesting a potential role in the treatment of benign prostatic hyperplasia. The selective antagonist Epelsiban was designed to work on peripheral human oxytocin receptors and not to readily pass the blood–brain barrier. However Epelsiban was found to inhibited brain oxytocin receptors mediating ejaculation, when given intraventricularly to rodents. As expected, despite this success achieved in mice, oral epelsiban in humans at 50 or 150 mg has not shown satisfactory results in a double blind, placebo-controlled trial. This suggested that a central nervous system (CNS) penetrant oxytocin receptor antagonist would show an effect on ejaculation when given systemically. This has been achieved with the cligosiban which has good CNS penetration. Epelsiban was also investigated as an agent to enhance embryo or blastocyst implantation in women undergoing embryo or blastocyst transfer associated with in vitro fertilization (IVF). and for use in the treatment of adenomyosis.
Sources: en.wikipedia.org
==== Other types ==== Ricin is a two-component (AB) toxin made up of an A chain and the B chain, which form a tight heterodimer. The B chain is a lectin that binds to the surface of victim cells, triggering the internalization of the heterodimer. After the complex enters the cell, the catalytic A chain performs the function of depurinating ribosomal RNA, causing the inactivation of ribosomes.
==== Glycemic index ==== The glycemic index (GI) and glycemic load concepts characterize the potential for carbohydrates in food to raise blood glucose compared to a reference food (generally pure glucose). Expressed numerically as GI, carbohydrate-containing foods can be grouped as high-GI (score more than 70), moderate-GI (56–69), or low-GI (less than 55) relative to pure glucose (GI=100). Consumption of carbohydrate-rich, high-GI foods causes an abrupt increase in blood glucose concentration that declines rapidly following the meal, whereas low-GI foods with lower carbohydrate content produces a lower blood glucose concentration that returns gradually after the meal. Glycemic load is a measure relating the quality of carbohydrates in a food (low- vs. high-carbohydrate content – the GI) by the amount of carbohydrates in a single serving of that food.
However, the Federal Reserve does not receive a congressional appropriation as its budget (including for its building renovations) is instead entirely funded through its open market operations, by interest payments received from banks on loans procured through the Federal Reserve's discount window, and from other fees the Federal Reserve charges banks for other services (including check processing). Powell characterized the investigation as a pretext aimed at pressuring the Federal Reserve to lower interest rates, rather than a legitimate inquiry into his testimony or the renovation itself. He stated that the Fed had made extensive efforts to keep Congress informed through testimony and public disclosures. According to reporting, prosecutors reviewed Powell’s public statements and requested documentation from Federal Reserve staff related to the renovation. As of mid-January 2026, it remained unclear whether prosecutors had convened a grand jury beyond issuing subpoenas or whether formal charges would be sought. In March 2026, Judge James Boasberg ruled to quash Pirro's subpoenas, writing "the government has offered no evidence whatsoever that Powell committed any crime other than displeasing the president.” In a news conference, Pirro said she would appeal the order. In April 2026, amid pressure from Republican Senators, Pirro announced that the investigation had been closed.
Sources: en.wikipedia.org
Human-animal chimeras include humans having undergone non-human to human xenotransplantation, which is the transplantation of living cells, tissues or organs from one species to another. Patient derived xenografts are created by xenotransplantation of human tumor cells into immunocompromised mice, and is a research technique frequently used in pre-clinical oncology research.
==== Natural biocontrol and elicitor ==== In agriculture, chitosan is typically used as a natural seed treatment and plant growth enhancer, and as an ecologically friendly biopesticide substance that boosts the innate ability of plants to defend themselves against fungal infections. Degraded molecules of chitin/chitosan exist in soil and water. Chitosan applications for plants and crops are regulated in the USA by the Environmental Protection Agency, and the USDA National Organic Program regulates its use on organic certified farms and crops. EPA-approved, biodegradable chitosan products are allowed for use outdoors and indoors on plants and crops grown commercially and by consumers. In the European Union and United Kingdom, chitosan is registered as a "basic substance" for use as a biological fungicide and bactericide on a wide range of crops. The natural biocontrol ability of chitosan should not be confused with the effects of fertilizers or pesticides upon plants or the environment. Chitosan active biopesticides represent a new tier of cost-effective biological control of crops for agriculture and horticulture. The biocontrol mode of action of chitosan elicits natural innate defense responses within plant to resist insects, pathogens, and soil-borne diseases when applied to foliage or the soil. Chitosan increases photosynthesis, promotes and enhances plant growth, stimulates nutrient uptake, increases germination and sprouting, and boosts plant vigor.
The Spy Who Came In from the Cold is a 1965 British spy film directed and produced by Martin Ritt, adapted by Paul Dehn and Guy Trosper from the 1963 novel by John le Carré. It stars Richard Burton, Claire Bloom, and Oskar Werner, and features Sam Wanamaker, Cyril Cusack, Rupert Davies, George Voskovec, and Peter van Eyck in supporting roles. The film depicts British MI6 agent Alec Leamas' (Burton) mission as a faux defector who is given the task of sowing damaging disinformation about a powerful East German intelligence officer (Werner). As part of a charade, Leamas is apparently dismissed from the British secret intelligence service and becomes an embittered alcoholic. He also strikes up a relationship with Nan Perry (Bloom), a British communist. He is soon approached by East German agents in Britain, and he allows himself to be recruited and taken to continental Europe to sell his secrets for money. The plots of the rival spy agencies unfold, and prove more complicated than Leamas expected. The Spy Who Came In from the Cold was a box-office success, receiving positive reviews and several awards, including four BAFTA Awards for Best British Film, Best Actor (for Burton), Best Cinematography, and Best Production Design. For their performances, Burton was also nominated for the Academy Award for Best Actor while Werner won the Golden Globe Award for Best Supporting Actor. The film was named one of the top ten films of 1965 by the National Board of Review in the United States.
Sources: en.wikipedia.org
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.