Certificate of analysis is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-11-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
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.
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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
=== Neutron source === 252Cf has a number of specialized uses as a strong neutron emitter; it produces 139 million neutrons per microgram per minute. This property makes it useful as a startup neutron source for some nuclear reactors and as a portable (non-reactor based) neutron source for neutron activation analysis to detect trace amounts of elements in samples. Neutrons from californium are used as a treatment of certain cervical and brain cancers where other radiation therapy is ineffective. It has been used in educational applications since 1969 when Georgia Institute of Technology got a loan of 119 μg of 252Cf from the Savannah River Site. It is also used with online elemental coal analyzers and bulk material analyzers in the coal and cement industries. Neutron penetration into materials makes californium useful in detection instruments such as fuel rod scanners; neutron radiography of aircraft and weapons components to detect corrosion, bad welds, cracks and trapped moisture; and in portable metal detectors. Neutron moisture gauges use 252Cf to find water and petroleum layers in oil wells, as a portable neutron source for gold and silver prospecting for on-the-spot analysis, and to detect ground water movement. The main uses of 252Cf in 1982 were, reactor start-up (48.3%), fuel rod scanning (25.3%), and activation analysis (19.4%). By 1994, most 252Cf was used in neutron radiography (77.4%), with fuel rod scanning (12.1%) and reactor start-up (6.9%) as important but secondary uses. In 2021, fast neutrons from 252Cf were used for wireless data transmission.
== Mechanism == The nuclear force holding an atomic nucleus together is very strong, in general much stronger than the repulsive electromagnetic forces between the protons. However, the nuclear force is also short-range, dropping quickly in strength beyond about 3 femtometers, while the electromagnetic force has an unlimited range. The strength of the attractive nuclear force keeping a nucleus together is thus proportional to the number of the nucleons, but the total disruptive electromagnetic force of proton-proton repulsion trying to break the nucleus apart is roughly proportional to the square of its atomic number. A nucleus with 210 or more nucleons is so large that the strong nuclear force holding it together can just barely counterbalance the electromagnetic repulsion between the protons it contains. Alpha decay occurs in such nuclei as a means of increasing stability by reducing size. One curiosity is why alpha particles, helium nuclei, should be preferentially emitted as opposed to other particles like a single proton or neutron or other atomic nuclei. Part of the reason is the high binding energy of the alpha particle, which means that its mass is less than the sum of the masses of two free protons and two free neutrons. This increases the disintegration energy.
The treaty stipulated that East Germany would unify its territory with Federal Republic of Germany via Article 23 of the Basic Law, meaning that East Germany and the Volkskammer would cease to exist. The chamber's last legislative period therefore only lasted four and a half months. The treaty took effect on 3 October 1990; on the same day, 144 of the 400 Volkskammer deputies became members of the Bundestag (63 from the CDU, 33 from the SPD, 24 from the PDS, 9 from the BFD, 8 from the DSU, and 7 from Alliance 90 and the Green Party). The 8 DSU members joined the CDU/CSU Bundestag Group, briefly renamed CDU/CSU/DSU. The distribution of seats between these parties was determined by recalculating the results of the 1990 elections on a per-state basis. Their tenure came to an end two months later with the first all-German federal election on 2 December 1990.
=== Redox === Graphene oxide can be reversibly reduced and oxidized via electrical stimulus. Controlled reduction and oxidation in two-terminal devices containing multilayer graphene oxide films are shown to result in switching between partly reduced graphene oxide and graphene, a process that modifies electronic and optical properties. Oxidation and reduction are related to resistive switching.
The Group Experiment, which had been unavailable to English readers, is now available in an accessible translation by Jeffrey K. Olick and Andrew J. Perrin on Harvard University Press, along with introductory material explaining its relation to the rest of Adorno's work and 20th-century public opinion research.
Sources: en.wikipedia.org
=== Nomenclature === Often amide refers to carboxamide, and often amide refers to the anions R2N- and their derivatives. Tetrakis(dimethylamido)titanium (Ti(N(CH3)2)4) illustrates the ambiguity of the terminology.
Tiegs was elected in 1944 as a Fellow of the Royal Society, aged 47. In 1954 Oscar Tiegs was one of 23 Foundation Fellows of the Australian Academy of Science, and along with the other 22 foundation fellows was a petitioner to Queen Elizabeth II for the Academy's charter. He, Sydney Sunderland, and Thomas MacFarland Cherry, two other petitioners and foundation members were responsible for drafting the by-laws of the newly formed Academy. The Melbourne University's zoological museum, now called the Tiegs Museum, owes much of the quality of its collection to Oscar Tiegs. He spent time and care improving and extending its holdings, based on his belief in the traditional morphological approach to zoology. Oscar Tiegs was a prodigious worker, and, for example, would take on extra lecturing duties during staff absences to not load his other staff, and only in later years did he balance his time more out of work. He was fond of music, in particular Beethoven and Mozart, and critically appreciated pictures. These interests, of music, art, and literature he shared with his wife Ethel. Some felt Oscar Tiegs, while honest, was direct to the point of bluntness, and had a keen sense of humour. He was known for supportive letters sent to friends during World War II, and the gift parcels sent by him and his wife. Oscar Tiegs' geographical isolation, and his own diffidence probably prevented him from maximising his contribution to zoology, although rather than diffidence others describe it as an unassuming disposition.
Noriega's relationship with the U.S. deteriorated further during the late 1980s, particularly after the U.S. began to suspect that Noriega was supporting other intelligence services. Hersh wrote in 1986 that U.S. intelligence officials suspected that Noriega was selling intelligence to the Cuban government of Fidel Castro; his report received widespread attention. Bob Woodward published a story about Noriega in The Washington Post soon afterward, going into even greater detail about Noriega's intelligence connections. Woodward and Hersh's reputations made certain that the stories were taken seriously. Spadafora had also informed the U.S. Drug Enforcement Administration (DEA) of some of his findings about Noriega's involvement in drug smuggling. Multiple U.S. agencies continued to investigate Noriega despite opposition from the Reagan administration. In 1988 Noriega was indicted by U.S. federal grand juries in courts in Miami and Tampa on charges of drug-trafficking. The indictment accused him of "turning Panama into a shipping platform for South American cocaine that was destined for the U.S., and allowing drug proceeds to be hidden in Panamanian banks". Soon afterward an army colonel and a few soldiers made an attempt to overthrow Noriega; their poorly planned effort was crushed within a day. The presidential election of May 1989 was marred by fraud and violence. Coalición para la Liberación Nacional (Coalition for National Liberation), a pro-military coalition led by the PRD, named Carlos Duque, a former business partner of Noriega, as its candidate.
Sandbuster Sand-Resistant Oil SPF 2 Tropical Deluxe SPF 4 Mega-Tan SPF 4 Mademoiselle (SPF 4, SPF 8, and SPF 15) All Day (SPF 4, SPF 8, SPF 15, SPF 30, Kids SPF 30, and Gentle Block SPF 30) SPF + Color (SPF 8, SPF 15, SPF 20) - line renamed to "Sunless Tanning Creme with Sunblock" Sunless (Light, Dark, Deep Dark, Tanning Spray Dark, and Tanning Spray Deep Dark) Apres Soleil After Sun Revitalizing Aloe Mist Apres Soleil After Sun Moisture Replenishing Lotion Orange Gelee (SPF 4, SPF 8, SPF 15, and SPF 30) Ecran Solaire (SPF 15 and SPF 30 Kids) - Canada Product development scientists at Pfizer CHCG were John A. Scott (group manager), Alice Scheiner (after sun and high-SPF products), Eric M. Stroud (sunless products), Judy Meyer, Andrew Ortega, and Mary Williams (packaging). Two innovations in 1,3-dihydroxyacetone stability were invented during this time. The entire brand was eventually divested on October 7, 1999, to Schering-Plough.
Sources: en.wikipedia.org
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.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
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.