heptapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-02-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
==== Cognition ==== Verbal memory scores are frequently used as one measure of higher level cognition. These scores vary in direct proportion to estrogen levels throughout the menstrual cycle, pregnancy, and menopause. Furthermore, estrogens when administered shortly after natural or surgical menopause prevents decreases in verbal memory. In contrast, estrogens have little effect on verbal memory if first administered years after menopause. Estrogens also have positive influences on other measures of cognitive function. However the effect of estrogens on cognition is not uniformly favorable and is dependent on the timing of the dose and the type of cognitive skill being measured. The protective effects of estrogens on cognition may be mediated by estrogen's anti-inflammatory effects in the brain. Studies have also shown that the Met allele gene and level of estrogen mediates the efficiency of prefrontal cortex dependent working memory tasks. Researchers have urged for further research to illuminate the role of estrogen and its potential for improvement on cognitive function.
Diclofenac consumption has been associated with significantly increased vascular and coronary risk in a study including COX-2 inhibitors, diclofenac, ibuprofen and naproxen. Upper gastrointestinal complications were also reported. Major adverse cardiovascular events were increased by about a third by diclofenac, chiefly due to an increase in major coronary events. Compared with placebo, of 1000 patients allocated to diclofenac for a year, three more had major vascular events, one of which was fatal. Vascular death is increased significantly by diclofenac. In October 2020, the US Food and Drug Administration (FDA) required the prescribing information to be updated for all nonsteroidal anti-inflammatory medications to describe the risk of kidney problems in fetuses that result in low amniotic fluid.
Vitamin D: insufficiency is common in diabetics. Observational studies show that serum vitamin D is inversely associated with biomarkers of diabetes; impaired insulin secretion, insulin resistance, and glucose intolerance. It has been suggested that vitamin D may induce beneficial effects on diabetic complications by modulating differentiation and growth of pancreatic β-cells and protecting these cells from apoptosis, thus improving β-cells functions and survival. In particular, vitamin D supplementation has been shown to have positive effects on people with type 1 diabetes. Vitamin D has also been suggested to act on immune system and modulate inflammatory responses by influencing proliferation and differentiation of different immune cells., Moreover, deficiency of vitamin D may contribute to diabetic complications by inducing hyperparathyroidism, since elevated parathyroid hormone levels are associated with reduced β-cells function, impaired insulin sensitivity, and glucose intolerance. Finally, vitamin D may reduce the risk of vascular complications by modulating lipid profile. Antioxidants may have beneficial effects on diabetic complications by reducing blood pressure, attenuating oxidative stress and inflammatory biomarkers, improving lipid metabolism, insulin-mediated glucose disposal, and by enhancing endothelial function. Vitamin C has been proposed to induce beneficial effects by two other mechanisms.
For centuries, the Danes and Saxons had regarded each other as kindred peoples, sharing the same belief in the Germanic pantheon and frequently intermarrying, especially among the elite. Thus, the defeated Saxon warleader Widukind sought refuge with his father-in-law, Danish king Sigfred. The Royal Frankish Annals mentions that Widukind received substantial aid from Sigfred, though the exact nature of this aid is not explicitly stated. However, the chronicles do note that Sigfred and Charlemagne brokered a peace agreement some years later, indicating that Sigfred, upon hearing Widukind's plea, may have mustered his army and joined the war on the side of the Saxons. In response to the Danes' involvement in the war, Charlemagne seems to have recruited the Obotrites by promising them the Saxon portion of Holstein. This alliance with Charlemagne shifted the balance of power in the region. In 782, after another defeat of the Saxons, Charlemagne ordered the mass execution of 4,500 Saxons, an atrocity that became known as the Massacre of Verden. Following this brutal act, Charlemagne was nicknamed the "Butcher of Saxons" or "Saxonslaughterer." In 796, despite Saxony being fully under Frankish rule, the Saxons rose once more, supported by the Danes. The rebellion was triggered by the forced conscription of Saxons for the Frankish wars against the Avars. Moreover, Charlemagne, in alliance with the Obotrites, planned to subjugate the Danes, now led by King Gudfred Sigfredson. However, Gudfred struck first.
=== Molecular biology laboratories === Polyacrylamide is also often used in molecular biology applications as a medium for electrophoresis of proteins and nucleic acids in a technique known as PAGE. PAGE was first used in a laboratory setting in the early 1950s. In 1959, the groups of Davis and Ornstein and of Raymond and Weintraub independently published on the use of polyacrylamide gel electrophoresis to separate charged molecules. The technique is widely accepted today, and remains a common protocol in molecular biology labs. Acrylamide has other uses in molecular biology laboratories, including the use of linear polyacrylamide (LPA) as a carrier, which aids in the precipitation of small amounts of nucleic acids (DNA and RNA). Many laboratory supply companies sell LPA for this use. In addition, under certain conditions, it can be used to selectively precipitate only RNA species from a mixture of nucleic acids.
Sources: en.wikipedia.org
== History == Reslizumab was initially developed by Chuan-Chu Chou at Schering-Plough and was previously known as SCH-55700. In 1993, Chou and his group at Schering-Plough were granted the patent for the design, cloning and expression of the reslizumab drug. Ception Therapeutics acquired the drug and continued its development under the name CTx55700. In 2010, Ception Therapeutics was acquired by Cephalon for $250 million and the drug continued under development under the codename CEP-38072. In 2011, Teva Pharmaceuticals acquired Cephalon for $6.8 billion and continued the development of reslizumab.
In India's eyes, the United States would once again be regarded as untrustworthy." The Trump administration avoided sanctioning India for the Russian S-400 missile system, but sanctioned Turkey and China for the same purchases. President Trump has grown closer to India's BJP government, which shares the similar right-wing views, he has repeatedly praised Modi's leadership and avoided any negative criticism of the Indian government's actions on the citizenship and Kashmir disputes. The Trump administration is consistent with the Modi administration in combating "radical Islamic terrorism", and the US reiterates its support for India's elimination of terrorist training camp in Pakistan. In early 2020, India provided its agreement for terminating an export embargo on a medicinal drug known as hydroxychloroquine amidst the combat against the ongoing coronavirus (COVID-19) pandemic, after Trump threatened retaliation against India, if it did not comply with terminating the export embargo on hydroxychloroquine. In June 2020, during the George Floyd protests, the Mahatma Gandhi Memorial in Washington, D.C., was vandalised by unknown miscreants on the intervening night of June 2 and 3. The incident prompted the Indian Embassy to register a complaint with law enforcement agencies. Taranjit Singh Sandhu, the Indian Ambassador to the United States called the vandalism "a crime against humanity". U.S. President Donald Trump called the defacement of Mahatma Gandhi's statue a "disgrace".
=== Carbon dioxide transport === CO2 is carried in blood in three different ways. (The exact percentages vary depending whether it is arterial or venous blood). Most of it (about 70%) is converted to bicarbonate ions HCO−3 by the enzyme carbonic anhydrase in the red blood cells by the reaction CO2 + H2O → H2CO3 → H+ + HCO−3; about 7% is dissolved in the plasma; and about 23% is bound to hemoglobin as carbamino compounds. Hemoglobin, the main oxygen-carrying molecule in red blood cells, carries both oxygen and carbon dioxide. However, the CO2 bound to hemoglobin does not bind to the same site as oxygen. Instead, it combines with the N-terminal groups on the four globin chains. However, because of allosteric effects on the hemoglobin molecule, the binding of CO2 decreases the amount of oxygen that is bound for a given partial pressure of oxygen. The decreased binding to carbon dioxide in the blood due to increased oxygen levels is known as the Haldane effect, and is important in the transport of carbon dioxide from the tissues to the lungs. A rise in the partial pressure of CO2 or a lower pH will cause offloading of oxygen from hemoglobin, which is known as the Bohr effect.
=== Lethality === The mean lethal dose in rats (i.p.) for ATR is 143 mg/kg and for CATR is 2.9 mg/kg. This lethal dose of ATR takes approximately 150–180 minutes after injection until acute tubular necrosis occurred. This lethal dose varies across species and method of exposure. For example, the mean lethal dose of ATR in rats (s.c.) is 155 mg/kg. Published mean lethal doses of ATR in other species includes 250 mg/kg (s.c.) for rabbit, 200 mg/kg (i.p.) for guinea pig, and 15 mg/kg (i.v.) for dog.
Glycoprotein hormones, alpha polypeptide is a protein that in humans is encoded by the CGA gene. Thyroid-stimulating hormone (TSH) and the gonadotropin hormones human chorionic gonadotropin (hCG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) are heterodimers consisting of alpha and beta subunits (also called chains) that are associated non-covalently. The alpha subunits of these four human glycoprotein hormones are identical; however, their beta chains are unique and confer biological specificity. The protein encoded by this gene is the alpha subunit and belongs to the glycoprotein hormones alpha chain family. CGA levels are regulated by ELAVL1/HuR, and the small molecule Eltrombopag, which targets HuR/RNA interactions, has been shown to reduce CGA levels in human cultured cells.
Sources: en.wikipedia.org
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.