Everything below concerns Tuftsin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-08-09. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
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.
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.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
=== Extracellular vesicle cross-talk === Recent studies have highlighted the involvement of RAGE (Receptor for Advanced Glycation End-products) in mediating the intercellular communication through extracellular vesicles (EVs), particularly during inflammatory responses. RAGE, known for its interaction with various ligands including advanced glycation end-products (AGEs), plays a key role in the biogenesis and secretion of EVs from stressed or damaged cells. Extracellular vesicles, such as exosomes, are small lipid-bound vesicles that facilitate cell-to-cell communication by transferring molecular cargo including proteins, lipids, and RNAs between cells. Recent evidence suggests that RAGE-associated vesicular pathways contribute to the exacerbation of inflammation by enabling pro-inflammatory signaling between cells. Specifically, a study from 2023 demonstrated that β-cells exposed to cytokine-induced stress release EVs enriched with RAGE ligands, which were found to further activate RAGE signaling pathways in neighboring cells, promoting inflammatory responses and impairing insulin secretion. These EV-mediated effects were shown to propagate inflammation across multiple cell types, indicating that RAGE-associated vesicles may play a pivotal role in amplifying the immune response in metabolic disorders like diabetes. Another study from 2024 reported that EVs containing RAGE ligands could be detected in the bloodstream of patients with early-stage diabetes, suggesting the potential utility of these vesicles as biomarkers for early diagnosis of inflammatory diseases.
=== Ingestion === In the United States, the Center for Science in the Public Interest lists the two food preservatives, sulfur dioxide and sodium bisulfite, as being safe for human consumption except for certain asthmatic individuals who may be sensitive to them, especially in large amounts. Symptoms of sensitivity to sulfiting agents, including sulfur dioxide, manifest as potentially life-threatening trouble breathing within minutes of ingestion. Sulfites may also cause symptoms in non-asthmatic individuals, namely dermatitis, urticaria, flushing, hypotension, abdominal pain and diarrhea, and even life-threatening anaphylaxis.
The unsanitary conditions engendered by the war, severe overcrowding in barracks, wartime propaganda interfering with public health warnings, and migration of so many soldiers around the world helped the outbreak become a pandemic. Ultimately, World War I created a decisive break with the old world order that had emerged after the Napoleonic Wars, which was modified by the mid-19th century's nationalistic revolutions. The results of World War I would be important factors in the development of World War II approximately 20 years later.
Normally, the stereochemistry of the alkene is retained throughout the reaction, except under harsh reaction conditions. A variety of alkenes may be used, and these include both α- and β-halo-α,β unsaturated ketones, esters, and sulfoxides (which normally need a copper (I) additive to proceed), and more (see example below). Vinyl triflates are also sometimes used. Some reactions require the addition of LiCl and others are slowed down, implying that two mechanistic pathways are present.
13C + n → 14C In this case the atomic mass increases, but the element is unchanged. In other cases the product nucleus is unstable and decays, typically emitting protons, electrons (beta particle) or alpha particles. When a nucleus loses a proton the atomic number decreases by 1. For example,
Sources: en.wikipedia.org
There is evidence from both human and animal studies that inhalation exposure to ethylene oxide can result in a wide range of carcinogenic effects. Ethylene oxide is toxic by inhalation, with a US OSHA permissible exposure limit calculated as a TWA (time weighted average) over 8 hours of 1 ppm, and a short term exposure limit (excursion limit) calculated as a TWA over 15 minutes of 5 ppm. At concentrations in the air about 200 parts per million, ethylene oxide irritates mucous membranes of the nose and throat; higher contents cause damage to the trachea and bronchi, progressing into the partial collapse of the lungs. High concentrations can cause pulmonary edema and damage the cardiovascular system; the damaging effect of ethylene oxide may occur only after 72 hours after exposure. The maximum content of ethylene oxide in the air according to the US standards (ACGIH) is 1.8 mg/m3 (0.00079 gr/cu ft). NIOSH has determined that the Immediately Dangerous to Life and Health level (IDLH) is 800 ppm. Because the odor threshold for ethylene oxide varies between 250 and 700 ppm, the gas is already at toxic concentrations when it can be smelled. Even then, the odor of ethylene oxide is sweet and aromatic and can easily be mistaken for the aroma of diethyl ether, a common laboratory solvent of very low toxicity. In view of these insidious properties, continuous electrochemical monitoring is standard practice, and it is forbidden to use ethylene oxide to fumigate building interiors in the EU and some other jurisdictions.
Susie Orbach (born 6 November 1946), psychotherapist, psychoanalyst, writer and social critic; daughter of Maurice Orbach, author of Fat is a Feminist Issue, married to author Jeanette Winterson. She is honoured in BBC'S 100 Women in 2013 and 2014. She was the therapist to Diana, Princess of Wales during the 1990s. Yotam Ottolenghi (born 14 December 1968), Israeli-British celebrity chef; journalist for The Guardian and Haaretz; author of several cookery books, including Ottolenghi: The Cookbook (2008), Plenty (2010), Jerusalem (2012). Moved to Europe after his service in Military Intelligence Directorate (Israel); in 2014, London Evening Standard remarked that Ottolenghi had "radically rewritten the way Londoners cook and eat"; in 2017 was guest judge on Masterchef Australia. Ilan Pappé, pro-Palestinian dissident Israeli-British scholar, writer and author of Ashkenazi origin, focusing on the history of Palestinian Nakba, intifada, insurgency, land ownership and rights and radical Anti-Zionism. Joseph Pardo (c. 1624 – 1677), hazzan and writer David Patrikarakos; journalist and war correspondent, author of War in 140 Characters: How Social Media Is Reshaping Conflict in the Twenty-First Century; wrote Nuclear Iran: Birth of An Atomic State which was named as a New York Times Editor's Choice and nominated for Total Politics Book Awards. Ruthie Pearlman, Orthodox Jewish Crime Writer and writer of Young Adult Fiction.
== Interpretation == If the positive or negative controls fail, than the entire testing procedure is invalid and must be repeated. Criteria for a positive MMA will vary by laboratory, though the originally established threshold set by Sandra Nance et al., is >20% phagocytic activity observed. Clinically, a positive MMA would indicate that the patient's serum used in the assay contains clinically significant antibodies that are capable of causing antibody-mediated phagocytosis.
==== Binding of escitalopram to human SERT protein ==== Andersen et al. were able to generate a model of the (S)-citalopram binding site in human SERT by combining mutational analysis and comparative modeling where they found out that Asn-177 and Phe-341 where key determinants for (S)-citalopram potency and high affinity inhibition in addition to Tyr-95, Asp-98, Ile-172 and Ser438 previously described, where three functional groups of the inhibitors structure bind to the transporters amino acids. (S)-citalopram is positioned as that the cyanophthalane-. fluorophenyl- and methylaminoprpyl moieties occupy three different sub-pockets within the SERT binding pocket. Ile-172 and Phe-341 are likely not in direct contact with the drug molecule, but they are very important for controlling alignment of the inhibitor.
== External links == Metribolone at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Methyltrienolone - William Llewellyn's Anabolic.org Archived 2016-04-07 at the Wayback Machine
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.