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.
Updated 2026-02-08. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
| 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 |
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
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.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
The epithelial layer, known as mesothelium, consists of a single layer of avascular flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid. This fluid has a consistency similar to thin mucus. These cells are bound tightly to the underlying connective tissue. The connective tissue layer provides the blood vessels and nerves for the overlying secretory cells, and also serves as the binding layer which allows the whole serous membrane to adhere to organs and other structures. For the heart, the layers of the serous membrane are called the parietal pericardium, and the visceral pericardium (sometimes called the epicardium). Other parts of the body may also have specific names for these structures. For example, the serosa of the uterus is called the perimetrium.
Bang Energy is an American brand of energy drinks made by Vital Pharmaceuticals, a corporation located in Florida. In 2023, Bang was the third-highest-selling energy drink in the United States, behind Monster, and Red Bull. On July 31, 2023, Monster Beverage acquired Vital Pharmaceuticals for $362 million. Including the Bang Energy brand and a beverage facility in Phoenix, Arizona, the deal came months after the company filed for Chapter 11 bankruptcy protection.
=== Prescribing restrictions === Isotretinoin is a teratogen; there is about a 20–35% risk for congenital defects in infants exposed to the drug in utero, and about 30–60% of children exposed to isotretinoin prenatally have been reported to show neurocognitive impairment. Because of this risk, there are strict controls prescribing isotretinoin to women who have potential to become (or be) pregnant while taking isotretinoin and many are strongly advised to terminate their pregnancies because of the 20-60% risk. Isotretinoin is also not recommended for use by breastfeeding women. In the United States, since March 2006, the dispensing of isotretinoin is run through the iPLEDGE program, under the direction of the Food and Drug Administration. Prescribers, pharmacists, and all people to whom the drug is prescribed need to register on the site and log information into it. Women with child-bearing potential must commit to using two forms of effective contraception simultaneously for the duration of isotretinoin therapy and for a month immediately preceding and a month immediately following therapy. Additionally, they must have two negative pregnancy tests 30 days apart and have negative pregnancy tests before each prescription is written. In most countries, isotretinoin can only be prescribed by dermatologists or specialist physicians; some countries also allow limited prescriptions by general practitioners and family doctors. In the United Kingdom and Australia, isotretinoin may be prescribed only by or under the supervision of a consultant dermatologist.
== Staining procedural notes == Zenker fixative is preferred, although formalin fixed tissue can be used. If this is the case, the tissue should be mordanted in Zenkers solution before staining. Most texts recommend mordanting in Zenker fixative overnight at room temperature, but it can be done for 3.5 hours in a 56 to 60 degrees Celsius oven. PTAH solution, Gram Iodine, 5% sodium thiosulfate, 0.25% Potassium Permanganate, and 5% Oxalic Acid solution are needed. After staining, slides should be dehydrated quickly because the red-brown components lose their color when exposed to water or alcohol.
Seeking to improve selectivity through chemical modification, studies were performed to correlate lipid solubility with penetration of the blood-brain barrier in mice. It was determined that compounds with high solubility in benzene are more capable of penetrating the brain, and should thus be avoided as BNCT therapeutics. Based on this data, boron-10 enriched samples of p-carboxyphenylboronic acid (PCPB) and sodium decahydrodecaborate (Na2B10H10) were selected for BNCT at the Massachusetts Institute of Technology research reactor. The therapy was performed on eighteen patients before the realization that patients were receiving severe radiation damage to normal tissue ended the trial. Later analysis established the likely cause of death as radiation necrosis for at least nine patients, and the study has been described as a “total failure”. Radiation necrosis was attributed to fission of boron-10 atoms in the bloodstream, damaging adjacent blood vessels. PCPB and Na2B10H10 had been selected for their promising tumor:normal tissue differentials; however, the concentration of boron-10 in patients’ blood was not considered as significant a concern until after these results.
Sources: en.wikipedia.org
lipoprotein Any water-soluble protein to which one or more lipid molecules are attached by covalent bonding to amino acid residues. Many classes of lipids can be conjugated to proteins, including triacylglycerols, cholesterols, and phospholipids. Compare proteolipid.
=== Spring 1973 strategic situation === In February 1973, as the Khmer Rouge continued to win victories against the Lon Nol regime, American bombing of Cambodia was increased. On 15 March 1973, Nixon had implied during a speech that the United States might go back into Vietnam should the Communists violate the ceasefire, and, as a result, Congress began debating a bill to limit American funding for military operations in Southeast Asia. On 29 March 1973, the withdrawal of the Americans from Vietnam was complete, and on 1 April 1973, the last American POWs were freed. The peace agreement put into effect the "leopard's spot" ceasefire, with the Viet Cong being allowed to rule whatever parts of South Vietnam they held at the time of the ceasefire and all of the North Vietnamese troops in South Vietnam being allowed to stay, putting the Communists in a strong position to eventually take over South Vietnam. Public opinion polls in 1973 showed that 52% of Americans were opposed to military aid to South Vietnam if North Vietnam should violate the Paris peace accords and 71% were against the return of American troops to Vietnam. In April 1973, the CIA estimated the total number of PAVN troops in South Vietnam at 150,000 (about the same as in 1972), whereas Kissinger accused North Vietnam of moving more troops down the Ho Chi Minh Trail. That month, Kissinger met with Tho in Paris to reaffirm their commitment to the Paris peace agreement and to pressure him to stop the Khmer Rouge from overrunning Cambodia.
=== Sjögren syndrome === Sjögren syndrome (SS) is an autoimmune rheumatic disease of the exocrine glands. Increased incidence of SS after childbirth suggests a relationship between SS and pregnancy, and this led to the hypothesis that fetal microchimerism may be involved in SS pathogenesis. Studies showed the presence of Y-chromosome-positive fetal cells in minor salivary glands in 11 of 20 women with SS but in only one of eight normal controls. Fetal cells in salivary glands suggest that they may be involved in the development of SS.
=== Modification of natural polymers === Naturally occurring polymers such as cotton, starch, and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on the market. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulfur. Ways in which polymers can be modified include oxidation, cross-linking, and end-capping.
However, the conclusion was ambiguous as the overall content was above that expected of a male, and variations across the body may have been due to environmental factors. Similarly, green deposits were found in the hair, originally thought to be a copper-based pigment used for decoration, but it was later found to be the result of a reaction between the keratin in the hair and the acid of the peat bog.
Sources: en.wikipedia.org
Furthermore, harkening back to Urey's original hypothesis of a "post-impact" reducing atmosphere, a recent atmospheric modeling study has shown that an iron-rich impactor with a minimum mass around 4×1020 – 5×1021 kg would be enough to transiently reduce the entire prebiotic atmosphere, resulting in a Miller–Urey-esque H2-, CH4-, and NH3-dominated atmosphere that persists for millions of years. Previous work has estimated from the lunar cratering record and composition of Earth's mantle that between four and seven such impactors reached the Hadean Earth.
It was only during the 1980s that a consensus among researchers was reached that these vessels can preserve as much as 30 to 40% of coronary blood flow to an otherwise-occluded blood vessel, and, while not capable of preventing ischemia in the event of high-output exercise, can nevertheless maintain aortic, pulmonic, and atrial blood pressure, redirect ST elevation into less serious ST depression in ischemia, and prevent infarction and symptoms of infarction, even in the case of complete left main coronary artery stenosis. The native collaterals are small vessels, with a narrow endothelial lining, a layer or two of smooth muscle, and a variable amount of elastic tissue. They are rarely if ever observed during angiography in the absence of severe ischemia (vessels less than 200 micrometers are not visible, generally), and only coronary stenosis, anemia, and exercise have experimentally been shown to cause transformation. Most observers agree that a 90% occlusion is necessary to bring about transformation in the absence of other factors, though a recent article suggests that they may appear as a result of coronary spasm in the absence of total occlusion (see below). Within ninety seconds of occlusion, the pressure gradient between the segment of the coronary vessel distal to the occlusion and the incipient collateral vessel precipitates damage to the internal elastic lamina, provoking an inflammatory response; monocytes and polycytes migrate to the vascular wall, which has, as a result of the occlusion, become permeable to the blood's cellular components.
Tadalafil, sold under the brand name Cialis among others, is a medication used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension. It is taken by mouth. Onset is typically within half an hour and the duration is up to 36 hours. Common side effects include headache, muscle pain, flushing, and nausea. Caution is advised in those with cardiovascular disease. Rare but serious side effects include a prolonged erection that can lead to damage to the penis, vision problems, and hearing loss. Tadalafil is not recommended in people taking nitrovasodilators such as nitroglycerin, as this may result in a serious drop in blood pressure. Tadalafil is a PDE5 inhibitor which increases blood flow to the penis. It also dilates blood vessels in the lungs, which lowers the pulmonary artery pressure. Tadalafil was approved for medical use in the United States in 2003. It is available as a generic medication. In 2022, it was the 172nd most commonly prescribed medication in the United States, with more than 3 million prescriptions.
== Timeline == 1999 – CLASP was established by three founding organizations – the Alliance to Save Energy, the International Institute for Energy Conservation, and Lawrence Berkeley National Laboratory. 2000 – CLASP's first website launched in July, 2000. 2002 – CLASP was registered as a World Summit on Sustainable Development (WSSD) partnership. 2004 – From 2000 to 2004, CLASP provided assistance for the development and implementation of 21 new minimum energy performance standards, energy efficiency endorsement labels, and energy information labels that will save 250 megatons of CO2 by 2014. 2005 – CLASP became an independent 501(c)(3) non-profit corporation. 2007 – CLASP became the Secretariat of Asia-Pacific Economic Cooperation Energy Standards Information System (APEC ESIS) under direction of the APEC ESIS Project Overseers (now Japan) and Expert Group on Energy Efficiency and Conservation (EGEE&C). 2009 – CLASP joined the ClimateWorks Foundation's network as a Best Practice Network (BPN) in March. 2011 – CLASP was appointed as the Operating Agent of Super-efficient Equipment and Appliance Deployment (SEAD), a government-led international market transformation initiative for highly efficient appliances and equipment. 2012 – CLASP website was selected by the 16th Annual Webby Awards as an Official Honoree in the Green category.
== Brands == Folgers established brand colors, included on their logo, were traditionally a moderately dark red background with white lettering. The white or grey lettering is still used, with a green background signifying decaf and a black background signifying their Noir dark roast. Folgers products available in the United States include:
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.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.