Everything below concerns Pro-Gly-Pro. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| 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 |
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.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
=== Promethium === In the second half of the 20th century, radium was progressively replaced with paint containing promethium-147. Promethium is a low-energy beta-emitter, which, unlike alpha emitters like radium, does not degrade the phosphor lattice, so the luminosity of the material will not degrade so quickly. It also does not emit the penetrating gamma rays which radium does. The half-life of 147Pm is only 2.62 years, so in a decade the radioactivity of a promethium dial will decline to only 1/16 of its original value, making it safer to dispose of, compared to radium with its half-life of 1600 years. This short half-life meant that the luminosity of promethium dials also dropped by half every 2.62 years, giving them a short useful life, which led to promethium's replacement by tritium. Promethium-based paint was used to illuminate Apollo Lunar Module electrical switch tips and painted on control panels of the Lunar Roving Vehicle.
=== Pharmacokinetics === After ingestion, bisoprolol is absorbed and has a high bioavailability of approximately 90% with a plasma half-life of 10–12 hours. Typically, half the circulating bisoprolol is metabolized by the liver, the rest passing unchanged through the kidneys before elimination; less than 2% may be excreted in the feces. Bisoprolol is soluble in both lipids and water. It is classified as a beta blocker with moderate lipophilicity and hence intermediate potential for crossing the blood–brain barrier. This in turn may result in fewer effects in the central nervous system as well as a lower risk of neuropsychiatric side effects than highly lipophilic beta blockers like propranolol but greater such effects than beta blockers with low lipophilicity like atenolol. The plasma protein binding of bisoprolol is approximately 35%, the volume of distribution is 3.5 L/kg and the total clearance is approximately 15 L/h. Bisoprolol is eliminated from the body in two ways - 50% of the substance is converted in the liver to inactive metabolites, which are then excreted in the kidneys. The remaining 50% is eliminated unchanged via the kidneys. Since elimination is equal in liver and kidney, no dose adjustment is required in patients with hepatic or renal impairment. The pharmacokinetics of bisoprolol are linear and independent of age. In patients with chronic heart failure, the plasma level of bisoprolol is higher and the half-life is longer than in healthy subjects when compared across studies.
Liraglutide, a GLP-1 receptor agonist taken by subcutaneous injection once daily. Naltrexone/bupropion, a combination of naltrexone and bupropion taken by mouth twice daily. Orlistat is a lipase inhibitor taken by mouth three times daily with each main meal containing fat. Orlistat reduces intestinal fat absorption by inhibiting pancreatic lipase. Over the longer term, average weight loss on orlistat is 2.9 kg (6.4 lb). It leads to a reduced incidence of diabetes, and has some effect on cholesterol. However, there is little information on how it affects the longer-term complications or outcomes of obesity. It also inhibits absorption of fat soluble vitamins; vitamins A, D, E and K, so supplementation is needed for those on orlistat. Phentermine/topiramate combination of phentermine and topiramate taken by mouth once daily. Semaglutide, a GLP-1 receptor agonist taken by subcutaneous injection once weekly. Tirzepatide is a gastric inhibitory polypeptide (GIP) analog and a GLP-1 receptor agonist taken by subcutaneous injection once weekly. As of 2023, tirzepatide has shown the greatest weight reduction of medications. Phendimetrazine, diethylpropion, and phentermine are approved by the FDA for short term use, up to 12 weeks at a time.
The neighbouring powers took advantage of the situation: the Habsburg Monarchy annexed the northwestern part of Moldavia, or Bukovina, in 1775, and the Russian Empire seized the eastern half of Moldavia, or Bessarabia, in 1812. A census revealed that the Romanians were more numerous than any other ethnic group in Transylvania in 1733, but legislation continued to use contemptuous adjectives (such as "tolerated" and "admitted") when referring to them. The Uniate bishop, Inocențiu Micu-Klein, who demanded recognition of the Romanians as the fourth privileged nation, was forced into exile. Uniate and Orthodox clerics and laymen jointly signed a plea for the Transylvanian Romanians' emancipation in 1791, but the monarch and the local authorities refused to grant their requests.
Sources: en.wikipedia.org
A large number of progestins, or synthetic progestogens, have been derived from progesterone. They can be categorized into several structural groups, including derivatives of retroprogesterone, 17α-hydroxyprogesterone, 17α-methylprogesterone, and 19-norprogesterone, with a respective example from each group including dydrogesterone, medroxyprogesterone acetate, medrogestone, and promegestone. The progesterone ethers quingestrone (progesterone 3-cyclopentyl enol ether) and progesterone 3-acetyl enol ether are among the only examples that do not belong to any of these groups. Another major group of progestins, the 19-nortestosterone derivatives, exemplified by norethisterone (norethindrone) and levonorgestrel, are not derived from progesterone but rather from testosterone. A variety of synthetic inhibitory neurosteroids have been derived from progesterone and its neurosteroid metabolites, allopregnanolone and pregnanolone. Examples include alfadolone, alfaxolone, ganaxolone, hydroxydione, minaxolone, and renanolone. In addition, C3 and C20 conjugates of progesterone, such as progesterone carboxymethyloxime (progesterone 3-(O-carboxymethyl)oxime; P4-3-CMO), P1-185 (progesterone 3-O-(L-valine)-E-oxime), EIDD-1723 (progesterone 20E-[O-[(phosphonooxy)methyl]oxime] sodium salt), EIDD-036 (progesterone 20-oxime; P4-20-O), and VOLT-02 (chemical structure unreleased), have been developed as water-soluble prodrugs of progesterone and its neurosteroid metabolites.
Berlin, Germany (suspended because of the Russo-Ukrainian war) Brno, Czech Republic (terminated because of the Russo-Ukrainian war) Chicago, United States (suspended because of the Russo-Ukrainian war) Düsseldorf, Germany (suspended because of the Russo-Ukrainian war) Kharkiv, Ukraine Kyiv, Ukraine Prague, Czech Republic (suspended since 2014 because of the Russo-Ukrainian war) Tallinn, Estonia Vilnius, Lithuania Warsaw, Poland (terminated because of the Russo-Ukrainian war)
=== Anthropogenic influences === Anthropogenic industry unintentionally injects micronutrients into various ecosystems across the globe. The addition of micronutrients into ecosystems can have both positive and negative impacts. In the face of climate change, the fertilization of oceans with iron has been proposed as a method of carbon sequestration; however, elevated levels of iron in high nutrient, low chlorophyll regions of the ocean can cause the production of harmful algal blooms which are toxic to both humans and marine life. Similarly, in lakes, isolated seas, and coastal bays or gulfs, addition of micronutrients can cause eutrophication leading to hypoxia, decreasing ecosystem health. Micronutrients are released into ecosystems from many anthropogenic activities. Fossil fuel combustion releases micronutrients such as Zn, Fe, Ni, and Cu into the atmosphere, surrounding soils, and nearby waterways. Agricultural fertilizer runoff contains many micronutrients like Fe, Mn, Zn, Cu, Co, B, Mo and Ni. Fertilizer runoff injects these micronutrients into groundwater, soils, and waterways. Deforestation decreases soil compaction, resulting in increased aeolian transport of dust containing micronutrients, especially Fe. Industrial mining produces tailings which contaminates runoff. The improper treatment of mining tailings can result in the leakage of micronutrients into groundwater, soils, and nearby waterways.
Texts on Wikisource: Beck, Archibald Frank (1911). "Waterloo Campaign, 1815". Encyclopædia Britannica. Vol. 28 (11th ed.). pp. 371–381. Maude, Frederic Natusch (1911). "Napoleonic Campaigns". Encyclopædia Britannica. Vol. 19 (11th ed.). pp. 212–236. Robinson, Charles Walker (1911). "Peninsular War". Encyclopædia Britannica. Vol. 21 (11th ed.). pp. 90–98. Rose, John Holland (1911). "Napoleon I.". Encyclopædia Britannica. Vol. 19 (11th ed.). pp. 190–211. "A new scholarly journal in 2023: European Review of Studies on the Napoleonic and Restoration Periods" The Legend of Bonaparte The Napoleonic Wars Exhibition held by The European Library 15th Kings Light Dragoons (Hussars) Re-enactment Regiment 2nd Bt. 95th Rifles Reenactment and Living History Society The Napoleonic Wars Collection Website Napoleon, His Army and Enemies Napoleonic Guide War and Peace by Leo Tolstoy at Project Gutenberg Napoleonic Wars Fondation Napoléon The Napoleon Series
Glutathione S-transferases (GSTs), previously known as ligandins, are a family of eukaryotic and prokaryotic phase II metabolic isozymes best known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to xenobiotic substrates for the purpose of detoxification. The GST family consists of three superfamilies: the cytosolic, mitochondrial, and microsomal—also known as MAPEG—proteins. Members of the GST superfamily are extremely diverse in amino acid sequence, and a large fraction of the sequences deposited in public databases are of unknown function. The Enzyme Function Initiative (EFI) is using GSTs as a model superfamily to identify new GST functions. GSTs can constitute up to 10% of cytosolic protein in some mammalian organs. GSTs catalyse the conjugation of GSH—via a sulfhydryl group—to electrophilic centers on a wide variety of substrates in order to make the compounds more water-soluble. This activity detoxifies endogenous compounds such as peroxidised lipids and enables the breakdown of xenobiotics. GSTs may also bind toxins and function as transport proteins, which gave rise to the early term for GSTs, ligandin.
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.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.