Everything below concerns Heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-04. Numbers and descriptions here follow the published literature rather than marketing material.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
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 studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
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.
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.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
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.
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.
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.
Methyl p-(hydroxymethyl)benzoate undergoes reaction with ethylene oxide with boron trifluoride etherate and dichloromethane to yield 2-hydroxyethyl ether. Then, the hydroxy group is substituted with tert-butyldimethylsilyl chloride (TMS-Cl) in dimethylformamide (DMF). Next, the ester is reduced into an according alcohol using lithium aluminium hydride (LAH) in tetrahydrofuran. The newly created hydroxy moiety undergoes addition with 2-tert-butyl-4-chloro-5-hydroxy-pyridazin-3-one. The TBSO group is then substituted with a tosyl group with a two-step reaction using (1) tetra-n-butylammonium fluoride (TBAF) in THF and (2) tosyl chloride in 4-dimethylaminopyridine (DMAP), triethylamine (TEA) and dichloromethane. To create the final radiolabelled radiopharmaceutical, potassium fluoride-18 is used. This step is performed using kryptofix, a phase-transfer catalyst, and acetonitrile. Kryptofix (5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5]tricosane), a cryptand, increases the solubility of the fluoride ion in organic solvents (here, acetonitrile), by chelating it.
The formation of thermodynamically stable copernicium(II) and (IV) fluorides would be analogous to the chemistry of xenon. Analogous to mercury(II) cyanide (Hg(CN)2), copernicium is expected to form a stable cyanide, Cn(CN)2.
== History == Spontaneous vertebral artery dissection was described in the 1970s. Prior to this, there had been isolated case reports about carotid dissection. In 1971, C. Miller Fisher, a Canadian neurologist and stroke physician working at Massachusetts General Hospital, first noted the "string sign" abnormality in carotid arteries on cerebral angiograms of stroke patients, and subsequently discovered that the same abnormality could occur in the vertebral arteries. He reported the discovery in a paper in 1978.
Withdrawal symptoms include headaches, anxiety, tension, depression, insomnia, restlessness, confusion, irritability, sweating, dysphoria, dizziness, derealization, depersonalization, numbness/tingling of extremities, hypersensitivity to light, sound, and smell, perceptual distortions, nausea, vomiting, diarrhea, appetite loss, hallucinations, delirium, seizures, tremor, stomach cramps, myalgia, agitation, palpitations, tachycardia, panic attacks, short-term memory loss, and hyperthermia. It takes about 18–36 hours for lorazepam to be removed from the body.
Sources: en.wikipedia.org
Dog saliva has been said by many cultures to have curative powers in people. "Langue de chien, langue de médecin" is a French saying meaning "A dog's tongue is a doctor's tongue", and a Latin quote that "Lingua canis dum lingit vulnus curat" or "A dog's saliva can heal your wound" appears in a thirteenth-century manuscript. In Ancient Greece, dogs at the shrine of Aesculapius were trained to lick patients, and snake saliva was also applied to wounds. Saint Roch in the Middle Ages was said to have been cured of a plague of sores by licking from his dog. The Assyrian Queen Semiramis is supposed to have attempted to resurrect the slain Armenian king Ara the Beautiful by having the dog god Aralez lick his wounds. In the Scottish Highlands in the nineteenth century, dog saliva was believed to be effective for treating wounds and sores. In the Gospel of Luke (16:19-31), Lazarus the Beggar's sores are licked by dogs, although no curative effects are reported by the Evangelist.
==== Indications ==== Cannabidiol, available as Epidiolex® in high concentration, is a synthetic non-classical cannabinoid marketed for the treatment of refractory epilepsy in patients with Dravet syndrome (epilepsy condition since infancy), Lennox-Gastaut syndrome (severe epilepsy in children), and tuberous sclerosis (a genetic condition causing the formation of non-cancerous tumours in different body areas) in patients aged 1 or above. A reduction in the frequency seizures (uncontrolled shaking of body due to abnormal brain activity) and a better seizure control are seen among patients.
== Death == Sun likely spent the last few years of his life as a monk, before working as a caretaker of the Guanghua temple in Beijing. He lived there until his death on 17 December 1996 at the age of 93.
Sources: en.wikipedia.org
In nuclear science a decay chain refers to the predictable series of radioactive disintegrations undergone by the nuclei of certain unstable chemical elements. Radioactive isotopes do not usually decay directly to stable isotopes, but rather into another radioisotope. The isotope produced by this radioactive emission then decays into another, often radioactive isotope. This chain of decays always terminates in a stable isotope, whose nucleus no longer has the surplus of energy necessary to produce another emission of radiation. Such stable isotopes are then said to have reached their ground states. The stages or steps in a decay chain are referred to by their relationship to previous or subsequent stages. Hence, a parent isotope is one that undergoes decay to form a daughter isotope. For example element 92, uranium, has an isotope with 144 neutrons (236U) and it decays into an isotope of element 90, thorium, with 142 neutrons (232Th). The daughter isotope may be stable or it may itself decay to form another daughter isotope. 232Th does this when it decays into radium-228. The daughter of a daughter isotope, such as 228Ra, is sometimes called a granddaughter isotope. 228Ra in turn undergoes a further eight decays and transmutations until a stable isotope, 208Pb, is produced, terminating the decay chain of 236U. The time required for an atom of a parent isotope to decay into its daughter is fundamentally unpredictable and varies widely. For individual nuclei the process is not known to have determinable causes and the time at which it occurs is therefore completely random.
== Function == The corticotropin-releasing hormone receptor binds corticotropin-releasing hormone, a potent mediator of endocrine, autonomic, behavioral, and immune responses to stress. CRF1 receptors in mice mediate ethanol enhancement of GABAergic synaptic transmission.
=== Modern era === In the 16th century Aquileia fell under the Habsburg County of Gorizia (later the Princely County of Gorizia and Gradisca), a part of the Holy Roman Empire. The patriarchal diocese was finally officially suppressed in 1751, and the sees of Udine and Gorizia were established from its territory. During the Napoleonic Wars Aquileia was annexed to the Napoleonic Kingdom of Italy by the 1807 Treaty of Fontainebleau. It returned to Austrian control in 1815 following the Congress of Vienna, initially as part of the Kingdom of Illyria, then the reconstituted Gorizia and Gradisca (part of the Austrian Littoral). Following the Austro-Hungarian defeat in World War I, Aquileia passed to the Kingdom of Italy in 1920 (Treaty of Rapallo).
== Potential uses == Lobeline has been sold, in tablet form, for use as a smoking cessation aid, but scientific research has not provided supporting evidence for this use. Lobeline has also been studied for the treatment of other drug addictions such as addiction to amphetamines, cocaine, or alcohol; however, there is limited clinical evidence of any efficacy.
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
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.