Everything below concerns pharmacokinetics. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
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.
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.
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.
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.
Grover CN, Cameron RE, Best SM: Investigating the morphological, mechanical and degradation properties of scaffolds comprising collagen, gelatin and elastin for use in soft tissue engineering. J Mech Behav Biomed Mater. 2012 Jun;10:62-74.
A small amount of D-phenylalanine appears to be converted to L-phenylalanine. D-Phenylalanine is distributed to the various tissues of the body via the systemic circulation. It appears to cross the blood–brain barrier less efficiently than L-phenylalanine, and so a small amount of an ingested dose of D-phenylalanine is excreted in the urine without penetrating the central nervous system. L-Phenylalanine is an antagonist at α2δ Ca2+ calcium channels with a Ki of 980 nM. In the brain, L-phenylalanine is a competitive antagonist at the glycine binding site of NMDA receptor and at the glutamate binding site of AMPA receptor. At the glycine binding site of NMDA receptor L-phenylalanine has an apparent equilibrium dissociation constant (KB) of 573 μM estimated by Schild regression which is considerably lower than brain L-phenylalanine concentration observed in untreated human phenylketonuria.L-Phenylalanine also inhibits neurotransmitter release at glutamatergic synapses in hippocampus and cortex with IC50 of 980 μM, a brain concentration seen in classical phenylketonuria, whereas D-phenylalanine has a significantly smaller effect.
The members of Es La Guerilla wanted to move in a different musical direction, but had rehearsed very little with Kévone, the band's singer, before entering the recording studio. Kévone was less interested in the band's new direction. After a while, Nackphouminh tried his hand at singing.
Sources: en.wikipedia.org
Ptaquiloside is a norsesquiterpene glucoside produced by bracken ferns (majorly Pteridium aquilinum) during metabolism. It is identified to be the main carcinogen of the ferns and to be responsible for their biological effects, such as haemorrhagic disease and bright blindness in livestock and oesophageal, gastric cancer in humans. Ptaquiloside has an unstable chemical structure and acts as a DNA alkylating agent under physiological conditions. It was first isolated and characterized by Yamada and co-workers in 1983. The pure form ptaquiloside is a colorless amorphous compound. It is readily soluble in water and fairly soluble in ethyl acetate. Except in the plants, ptaquiloside has been detected in the milk and meat of affected livestock, as well as in the underground water and dry soil around bracken fern vegetation. The prevalence of ptaquiloside in daily sources along with its carcinogenic effects make it an increasing biological hazard in modern days.
== Spies == John Vardill (1766), loyalist educator, pamphleteer, spy William Joseph Donovan (1905), head of the Office of Strategic Services, predecessor to the Central Intelligence Agency, "father of American intelligence" Isaiah Oggins (1920), communist activist and Soviet spy Whittaker Chambers* (1924), Soviet spy and accuser of Alger Hiss Nathaniel Weyl (1931), operative in the Ware group of Soviet spies in the U.S. Victor Perlo (1933), leader of the Perlo group of Soviet spies in the U.S. Frank Snepp (1965), former CIA station chief for Saigon during the Vietnam War
=== 2000–2005 === In 2000, the company acquired Hitech Pathology (Victoria) that merged with Melbourne Pathology. In 2001, Sonic Healthcare acquired Castlereagh Imaging (New South Wales), Castlereagh Imaging Hong Kong (HK), Hunter Imaging Group (New South Wales), Illawarra Radiology Group (New South Wales), Canterbury Medical Imaging (New Zealand), Palmerston North X-Ray (New Zealand), (through Sullivan Nicolaides Pathology) Consultant Pathologists in Townsville (Queensland) and Cairns Pathology Laboratory (Queensland), Queensland X-Ray Group, Illawarra Medical Laboratories (New South Wales), Clinipath Pathology (Western Australia), La Trobe Pathology (Victoria) and Bunbury Pathology (Western Australia) from Foundation Healthcare, and SKG Radiology (Western Australia's largest private diagnostic imaging practice). In 2002, the company acquired The Doctors Laboratory, Britain's largest private pathology practice. Through Sullivan Nicolaides the company acquired the practice of Tom Lynch in Rockhampton (Queensland). Through SKG Radiology, the company acquired Fremantle Radiology (Western Australia). Sonic Healthcare acquired Richard Haskell's NSW Central Coast Pathology practice in 2003, along with the Southside Diagnostic Services Group in Brisbane. In the UK, the company acquired Omnilabs Pathology, merging it into The Doctors Laboratory.
Sources: en.wikipedia.org
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.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
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.