If you have been reading about Semax 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 2026-01-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
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.
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
=== Phase 2 === AB-2004 – microbiome modulator Acamprosate (AOP-2020; Campral; SF-679/SF-775; SF-999) – unknown / GABAA receptor positive allosteric modulator and ionotropic glutamate NMDA receptor antagonist Alogabat (RG-7816, RG7816, RO-7017773; GABA-A-α5 PAM) – GABAA α5 subunit-containing receptor positive allosteric modulator Arbaclofen ((R)-baclofen; STX-209) – GABAB receptor agonist Cannabidiol (CBD; Epidiolex) – cannabinoid receptor modulator, other actions Cannabidiol transdermal patch/gel (Zygel; ZYN-002) – cannabinoid receptor modulator, other actions Cannabidivarin (CBDV; GWP-42006) – non-intoxicating cannabinoid receptor modulator, other actions CP-101 – bacteria relacement and gastrointestinal microbiome modulator JNJ-42165279 (JNJ-5279) – fatty acid amide hydrolase (FAAH) inhibitor Non-racemic MDMA (ALA-002; 70–80% (R)-MDMA, 20–30% (S)-MDMA) – serotonin, norepinephrine, and dopamine releasing agent, weak serotonin 5-HT2A, 5-HT2B, 5-HT2C receptor agonist, entactogen, and weak psychedelic hallucinogen Oxytocin (intranasal potentiated oxytocin; TI-001, TI-114, TNX-1900, TNX-2900) – oxytocin receptor agonist Pitolisant (Wakix; tiprolisant) – histamine H3 receptor inverse agonist Racemetirosine (DL-α-methyltyrosine; L1-79) – tyrosine hydroxylase inhibitor Suramin (IV suramin; PAX-101/PAX-102) – DNA synthesis inhibitor and anti-purinergic agent Zolmitriptan modified-release (ML-004, ML004) – serotonin 5-HT1B and 5-HT1D receptor agonist
==== Labeling ==== The FDA does not require special labels for products produced from cows given rBST, but has charged several dairies with "misbranding" their milk as having no hormones, because all milk contains hormones and cannot be produced in such a way that it would not contain any hormones. Monsanto sued Oakhurst Dairy of Maine over its use of a label which pledged not to use artificial growth hormones. The dairy stated that its disagreement was not over the scientific evidence for the safety of rBST (Monsanto's complaint about the label), but, "We're in the business of marketing milk, not Monsanto's drugs." The suit was settled when the dairy agreed to add a qualifying statement to its label: "FDA states: No significant difference in milk from cows treated with artificial growth hormones." The FDA recommends this additional labeling, but does not require it. The settlement itself caused much controversy, with anti-rBST advocates claiming that Oakhurst had capitulated in response to intimidation by a larger corporation and others claiming that Oakhurst's milk labels were in and of themselves using misleading scare tactics that deserved legal and legislative response.
British Military History – Including British Indian Army during WW2 The Indian Army 1900–1939. Archived 5 July 2019 at the Wayback Machine. The Indian Army Archived 24 March 2023 at the Wayback Machine – talk by Rob Lyman on WWII Indian Army at We Have Ways Festival
Sources: en.wikipedia.org
=== Connective tissue === Connective tissues are fibrous and made up of cells scattered among inorganic material called the extracellular matrix. Often called fascia (from the Latin "fascia", meaning "band" or "bandage"), connective tissues give shape to organs and hold them in place. The main types are loose connective tissue, adipose tissue, fibrous connective tissue, cartilage and bone. The extracellular matrix contains proteins, the chief and most abundant of which is collagen. Collagen plays a major part in organizing and maintaining tissues. The matrix can be modified to form a skeleton to support or protect the body. An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization, as in crustaceans or by the cross-linking of its proteins as in insects. An endoskeleton is internal and present in all developed animals, as well as in many of those less developed.
== Cacao == Chocolate is made from cocoa beans, the dried and often fermented seeds of the cacao tree (Theobroma cacao), a small, 4–8 m (13–26 ft) tall evergreen tree native to South America. The most common genotype originated in the Amazon basin, and was gradually transported by humans throughout South and Central America. Early forms of another genotype have also been found in what is now Venezuela. The scientific name, Theobroma, means "food of the gods". The fruit, called a cocoa pod, is ovoid, 15–30 cm (6–12 in) long and 8–10 cm (3–4 in) wide, ripening yellow to orange, and weighing about 500 g (1.1 lb) when ripe. Cacao trees are small, understory trees that need rich, well-drained soils. They naturally grow within 20° of either side of the equator because they need about 2000 mm of rainfall a year, and temperatures in the range of 21–32 °C (70–90 °F). Cacao trees cannot tolerate a temperature lower than 15 °C (59 °F). The genome of the cacao tree was sequenced in 2010. Traditionally, cacao was understood to be divided into three varieties: Criollo, Forastero, and Trinitario. New genetic research has not found a genetic backing for this division, and it has identified eleven genetic clusters.
==== Hypogonadism ==== An absolute deficiency in androgen production due to primary or secondary hypogonadism can cause gynecomastia. Primary hypogonadism results when there is damage to the testes (due to radiation, chemotherapy, infections, trauma, etc.), leading to impaired androgen production. It can also be caused by chromosomal abnormality seen in Klinefelter syndrome, which is associated with gynecomastia in about 80% of cases. Secondary hypogonadism results when there is damage to the hypothalamus or pituitary (due to radiation, chemotherapy, infection, trauma, etc.), and similarly leads to impaired androgen production. The net effect is reduced androgen production while serum estrogen levels (from peripheral aromatization of androgens) remain unaffected. The lack of androgen-mediated inhibition of breast tissue proliferation, combined with relative estrogen excess, results in gynecomastia.
Sources: en.wikipedia.org
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.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
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.