Semax raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-08-11. Anything still debated is marked as such rather than presented as settled.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
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.
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.
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.
Bain de Soleil was an American brand of sunscreen that was produced by Bayer. The brand was known for low-SPF products that were typically marketed to women seeking skin tanning. It was affiliated with the Coppertone brand. The name Bain de Soleil is French for "sun bathing." The brand used the slogan "Welcome to a place more colorful." In the 1970s and 1980s, the brand used the slogan (especially featured in television commercials) "Bain de Soleil, for the St. Tropez tan." The brand was discontinued in December 2019.
== Chemistry == Protriptyline is a tricyclic compound, specifically a dibenzocycloheptadiene, and possesses three rings fused together with a side chain attached in its chemical structure. Other dibenzocycloheptadiene TCAs include amitriptyline, nortriptyline, and butriptyline. Protriptyline is a secondary amine TCA, with its N-methylated analog N–methylprotriptyline being a tertiary amine, and a structural isomer of amitriptyline. The tertiary amine analog of protriptyline, N–methylprotriptyline, has not been marketed. Other secondary amine TCAs include desipramine and nortriptyline. The chemical name of protriptyline is 3-(5H-dibenzo[a,d][7]annulen-5-yl)-N-methylpropan-1-amine and its free base form has a chemical formula of C19H21N1 with a molecular weight of 263.377 g/mol. The drug is used commercially mostly as the hydrochloride salt; the free base form is not used. The CAS Registry Number of the free base is 438-60-8 and of the hydrochloride is 1225-55-4.
== Cited sources == Vandenbosch, Robert & Vandenbosch, Susanne E. (2007). Nuclear waste stalemate. Salt Lake City: University of Utah Press. ISBN 978-0874809039. Hecker, Siegfried S. (2000). "The Plutonium Challenge-Environmental Issues". Los Alamos Science (26). Los Alamos National Laboratory: 36–47. Retrieved 1 October 2023.
Sources: en.wikipedia.org
== Prevention == Historically, about half of all burns were deemed preventable. Burn prevention programs have significantly decreased rates of serious burns. Preventive measures include: limiting hot water temperatures, smoke alarms, sprinkler systems, proper construction of buildings, and fire-resistant clothing. Experts recommend setting water heaters below 48.8 °C (119.8 °F). Other measures to prevent scalds include using a thermometer to measure bath water temperatures, and splash guards on stoves. While the effect of the regulation of fireworks is unclear, there is tentative evidence of benefit with recommendations including the limitation of the sale of fireworks to children.
Arthrodesis, also known as joint fusion, is the artificial induction of joint ossification between two bones by surgery. This is done to relieve intractable pain in a joint which cannot be managed by pain medication, splints, or other normally indicated treatments. The typical causes of such pain are fractures which disrupt the joint, severe sprains, and arthritis. It is most commonly performed on joints in the spine, hand, ankle, and foot. Historically, knee and hip arthrodeses were also performed as pain-relieving procedures, but, with the great successes achieved in hip and knee arthroplasty, arthrodesis of these large joints has fallen out of favour as a primary procedure and now is only used as a last resort in some failed arthroplasties.
In 2011, Antonio Lombatti noted several of these visual impossibilities in the body, such as the right footprint wrongly depicted in the shroud, and the locks of hair printed at the same height as the face, as if they were a solid structure, instead of resting on the ground. Lombatti further commented that the pressure from the body lying on the sheet should have caused the back image to be darker than the front image, which does not happen in the depiction of the shroud. The way the blood flows in rivulets from the head without mixing with the hair also struck him as more artistic than realistic. In 2018 an experimental Bloodstain Pattern Analysis (BPA) was performed to study the behaviour of blood flows from the wounds of a crucified person, and to compare this to the evidence on the Turin Shroud. The comparison between different tests demonstrated that the blood patterns on the forearms and on the back of the hand are not connected, and would have had to occur at different times, as a result of a very specific sequence of movements. In addition, the rivulets on the front of the image are not consistent with the lines on the lumbar area, even supposing there might have been different episodes of bleeding at different times. These inconsistencies suggest that the Turin linen was an artistic or didactic representation, rather than an authentic burial shroud.
Sources: en.wikipedia.org
=== Chemical-pharmaceutical industry and laboratories === Acetonitrile is used as a solvent, particularly in the pharmaceutical industry. According to a market analysis, approximately 180,000 tons of acetonitrile were produced worldwide in 2022, of which around 70% was consumed by the pharmaceutical sector. It is also one of the most important solvents for analyses performed by high-performance liquid chromatography. The thermal decomposition of azobisisobutyronitrile (AIBN) and related compounds (e.g., azobis(cyclohexanecarbonitrile)) generates relatively stable radicals; accordingly, these compounds are used as radical initiators in radical reactions, particularly polymerizations. The quinone DDQ, which contains two nitrile groups, is a widely used oxidizing agent, including in pharmaceutical synthesis. Nitrile groups can be incorporated into biomolecules as probes for infrared spectroscopic investigations. Some nitriles serve as starting materials for the synthesis of pharmaceuticals. Ketoprofen is an anti-inflammatory agent approved in some EU countries; propionitrile is used in its industrial synthesis.
Ajinomoto Co., Inc. (味の素株式会社, Ajinomoto kabushiki gaisha; Japanese pronunciation: [a.(d)ʑi.noꜜ.mo.to]) is a Japanese multinational food and biotechnology corporation which produces seasonings, cooking oils, frozen foods, beverages, sweeteners, amino acids, insulating films, and pharmaceuticals. Aji-No-Moto (味の素, "essence of taste") is the trade name for the company's original monosodium glutamate (MSG) product, the first of its kind, since 1909. The corporation's head office is located in Chūō, Tokyo. As of 2024, Ajinomoto operates in 31 countries worldwide and employs an estimated 34,862 people. Its yearly revenue in 2024 is around ¥1.53 trillion JPY or $10.61 billion USD.
=== Automatic Fraction Collector === The Automatic Fraction Collector (AFC) is a programmable, automation technology designed to enhance the reproducibility and scalability of sample collection from qEV columns. The AFC manages the collection of fractions from the qEV column by differentiating between the buffer volume, and the volume of fractions containing extracellular vesicles. It has an in-built rotational carousel for holding collection tubes, and precisely measures the volume of each fraction by weight as the sample elutes from the column. Together, qEV columns and the AFC are known as the qEV isolation platform. Multiple AFCs can be used in parallel to increase the throughput of extracellular vesicle isolation.
A hormone can perform functions over a larger spatial and temporal scale than can a neurotransmitter, which often acts in micrometer-scale distances. Hormonal signals can travel virtually anywhere in the circulatory system, whereas neural signals are restricted to pre-existing nerve tracts. Assuming the travel distance is equivalent, neural signals can be transmitted much more quickly (in the range of milliseconds) than can hormonal signals (in the range of seconds, minutes, or hours). Neural signals can be sent at speeds up to 100 meters per second. Neural signalling is an all-or-nothing (digital) action, whereas hormonal signalling is an action that can be continuously variable as it is dependent upon hormone concentration. Neurohormones are a type of hormone that share a commonality with neurotransmitters. They are produced by endocrine cells that receive input from neurons, or neuroendocrine cells. Both classic hormones and neurohormones are secreted by endocrine tissue; however, neurohormones are the result of a combination between endocrine reflexes and neural reflexes, creating a neuroendocrine pathway. While endocrine pathways produce chemical signals in the form of hormones, the neuroendocrine pathway involves the electrical signals of neurons. In this pathway, the result of the electrical signal produced by a neuron is the release of a chemical, which is the neurohormone. Finally, like a classic hormone, the neurohormone is released into the bloodstream to reach its target.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
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.