Everything below concerns nootropic. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
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 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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
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.
== Synthesis == Chymopapain is no longer used as a standard method to treat chronic low back pain because of its potential side effects. Therefore, there is no need to synthesize it artificially. In fact, the sale and distribution of this protein was discontinued in the US in 2003. Despite the huge amount of successful use to treat herniated disk disease, chymopapain use was discontinued not because of hazards or inadequacies but rather because it is no longer available due to a decision by its sole manufacturer to stop production. However, several studies have demonstrated different successful methods to extract and isolate the protease, which vary among authors. The most common procedure is the one described by Baines & Brocklehurst in 1979. In order to obtain the protein, Carica Papaya fruits are used, as chymopapain is found in its latex. The papayas should be just in the previous step before maturation, which implies an average diameter of 6–10 cm.
Radial chromatography is a form of chromatography, a preparatory technique for separating chemical mixtures. It can also be referred to as centrifugal thin-layer chromatography. It is a common technique for isolating compounds and can be compared to column chromatography as a similar process. A common device used for this technique is a Chromatotron. Here the solvent travels from the center of the circular chromatography silica layered on a plate towards the periphery. The entire system is kept covered in order to prevent evaporation of solvent while developing a chromatogram. The wick at the center of system drips solvent into the system which the provides the mobile phase and moves the sample radially to form the sample spots of different compounds as concentric rings. Continuous annular chromatography uses a stationary phase which is filled into an annular gap. The eluent is continuously fed across the whole bed interface also the feed is continuously fed at the top of the stationary however only at a certain point and not a cross the whole bed. The stationary phase is then rotated with a certain rotation speed. The rotation speed, eluent and feed flow rates have to be defined precisely such that the collector vessels only collect the correct substance. The retention times are transformed into the respective retention angles.
==== Quantities required ==== A rule of thumb for dry ice bath branding states that twenty pounds (9.1 kg) of dry ice and three US gallons (11 L) of 99% alcohol are sufficient to freeze-brand one hundred head of cattle inside a three to four-hour period. An entire day of freeze branding may consume 50–75 pounds (23–34 kilograms) of dry ice and six to nine US gallons (23 to 34 L) of ethanol. The dry ice should be broken up into egg-sized pieces, placed in a styrofoam container or styrofoam-insulated metal cooler and covered with at least three inches (7.6 cm) of alcohol. Many consumer coolers are made from plastics that become exceptionally brittle at cryogenic temperatures. This is a safety concern if heavy metal brands are frequently returned to coolant baths because 99% alcohol is extremely flammable. Insulated aluminum containers are preferred.
Sources: en.wikipedia.org
== Description == S. affinis is a perennial herbaceous plant with red to purple flowers and reaches a height of 30–120 centimetres (12–47 in). The green leaves are opposite arranged on the stem. The rough, nettle-like leaves can be ovate-cordate shaped with a width of 2.5–9.5 cm (1–3+3⁄4 in) or ovate-oblong with a width of 1.5–3.5 cm (5⁄8–1+3⁄8 in). The leaves are separated into a leaf blade and a petiole. The petiole has a length of 1–2 cm (3⁄8–3⁄4 in) and becomes shorter towards the stem apex. Similar to the potato, S. affinis grows rhizomes which are approximately 8 cm (3+1⁄8 in) long and 2 cm (3⁄4 in) thick. By medullary primary growth they thicken primarily on the internodes and less on the nodes. This way at irregular intervals constricted tubers are formed, which are usually thinner on both ends. The tubers are covered with a thin, pale-beige-to-ivory skin. The flesh underneath is white and tender.
Traditional non-alcoholic beverage companies, like PepsiCo, Fuze Beverage, and The Coca-Cola Company. Major food companies, such as Nestlé, Altria, Kraft Foods, General Mills, and the Campbell Soup Company. Smaller-scaled private companies and specialized companies like POM Wonderful. Agricultural cooperatives, such as Ocean Spray and Sunsweet Growers.
In Panjshir, residents reported hearing a loud explosion, and said that the Bazarak area was shaken by a strong tremor. In Herat, residents stated that fighter jets were patrolling over the city's airport and that gunfire was heard from the airport. In Badakhshan, residents reported that an airstrike had taken place in Fayzabad. Taliban officials did not release any official details regarding these airstrikes. A PAF airstrike was also reported in Afghanistan's Nuristan province. On the same day, a spokesperson for the Taliban-led Afghan government stated that, in the past 24 hours Taliban forces had attacked Pakistan's border outposts along the provinces of Kandahar, Nangarhar, Kunar, Nuristan, Khost, Paktika and Paktika. According to the spokesperson, since the start of the hostilities, Taliban forces had killed more than 150 Pakistan's troops, injured 200 others, and destroyed 40 border outposts belonging to Pakistan. Afghan MoD claimed that three Pakistani personnel were killed and one was captured in an attack on Pakistani forces in Spin Boldak. The spokesperson also stated that 28 Taliban fighters had been killed in the clashes, while 42 others had been wounded. As per the spokesperson, 110 Afghan civilians had been killed, while 120 others had been wounded. The spokesperson added that Pakistani attacks in Afghanistan have damaged public facilities, mosques, and houses. The spokesperson also said that Afghanistan has approached Russia, China, the European Union, and United Kingdom to help end the war.
Sources: en.wikipedia.org
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.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.