Tuftsin comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-05-22. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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 |
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.
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.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
(in French) Stéphane Sawas, «Entre amnésie collective et mémoire retrouvée: La guerre civile grecque au cinéma,» [Between Collective Amnesia and Rediscovered Memory: The Greek Civil War in Cinema] dans Carola Hähnel-Mesnard, Marie Liénard-Yeterian, et Cristina Marinas, directeurs de publication, Culture et mémoire: Représentations contemporaines de la mémoire dans les espaces mémoriels, les arts du visuel, la littérature et le théâtre [Culture and Memory: Contemporary Representations of Memory in Memorial Spaces, Visual Arts, Literature and Theater], Paris, Éditions de l'École Polytechnique et Éditions Ellipses, 2008, 534 pages, ISBN 978-2-7302-1492-6. (in French) Γιάννης Σολδάτος [Yannis Soldatos], Ιστορία του ελληνικού κινηματογράφου [History of Greek Cinema, tr. Istoría tou ellinikoú kinimatográfou], Β' Τόμος: 1967–1990, Αθήνα, Αιγόκερως, 2002, 383 σελίδες, ISBN 960-322-124-4. (in Greek)
Dyson, along with 33 other Essendon players, was found guilty of using a banned performance-enhancing substance, thymosin beta-4, as part of Essendon's sports supplements program during the 2012 season. He and his team-mates were initially found not guilty in March 2015 by the AFL Anti-Doping Tribunal, but a guilty verdict was returned in January 2016 after an appeal by the World Anti-Doping Agency. He was suspended for two years which, with backdating, ended in November 2016; as a result, he served approximately fourteen months of his suspension and missed the entire 2016 suburban football season.
Some psychedelics, including LSD, are metabolized by the cytochrome P450 enzyme CYP2D6. Concurrent use of selective serotonin reuptake inhibitors (SSRIs), some of which are potent inhibitors of CYP2D6, with LSD might heighten the risk of serotonin syndrome. However, according to other researchers, there is no risk of serotonin syndrome combining psychedelics like LSD and psilocybin with SSRIs. Chronic usage of SSRIs, tricyclic antidepressants (TCAs), and monoamine oxidase inhibitors (MAOIs) is believed to diminish the subjective effects of psychedelics, likely due to 5-HT2A receptor downregulation or desensitization induced by elevated serotonin levels. However, a clinical study found that administration of LSD to people taking paroxetine, an SSRI and strong CYP2D6 inhibitor, increased LSD exposure by about 1.5-fold, was well-tolerated, and did not modify the pleasant subjective effects or physiological effects of LSD, whereas negative effects of LSD, including "bad drug effect", anxiety, and nausea, were reduced. Similarly, a clinical study with LSD found that LSD levels were 75% higher in people with non-functional CYP2D6 (poor metabolizers) compared to those with functional CYP2D6. In contrast to certain other psychedelics, MAOIs do not inhibit the metabolism of or potentiate the effects of LSD and instead reduce its effects. Interactions between psychedelics and antipsychotics or anticonvulsants are not well-documented; however, co-use with mood stabilizers like lithium may induce seizures and dissociative effects, particularly in individuals with bipolar disorder.
Molecular engineering is an emerging field of study concerned with the design and testing of molecular properties, behavior and interactions in order to assemble better materials, systems, and processes for specific functions. This approach, in which observable properties of a macroscopic system are influenced by direct alteration of a molecular structure, falls into the broader category of “bottom-up” design. This field is utmost relevant to Cheminformatics, when related to the research in the Computational Sciences.
Since their introduction in the late 1980s, second-generation antidepressants have largely replaced first-generation antidepressants, such as tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs), as the drugs of choice for the treatment of MDD due to their improved tolerability and safety profile.
Sources: en.wikipedia.org
=== Tyrosine residues in resilin === Andersen, in 1996, discovered that the tyrosine residues are involved in chemically covalent cross-links in many forms such as dityrosine, trityrosine, and tetratyrosine. Primarily, in resilin, tyrosine and dityrosine served as the chemical cross-links, in which R groups of Tyrosine and Dityrosine add to the backbone of the growing peptide chain. Andersen came to this conclusion based on a study involving these two compounds in which he was able to rule out other forms of cross linking such as disulfide bridges, ester groups, and amide bonds. Though the mechanism of cross-linking of Tyrosine is understood that occurs through radical initiation, the cross linking of resilin still remains a mystery. Cross linking of resilin occurs very quickly and this is possibly a result of temperature. At increasing temperature, the rate of cross linking of the residues increases and leads to a highly cross-linked resilin network. The amino acid composition of resilin indicates that proline and glycine has a relatively high presence in the amino acid composition of resilin. The presence of glycine and proline in the composition of resilin contributes greatly to the elasticity of resilin. Resilin, however, has an absence of an alpha-helix leading to a randomly coiled structure and a disordered structure. This is primarily due to the significantly high proline content in resilin. Proline is a bulky amino acid that has the ability to cause a kink the peptide chain and due to the sterically hindered side chains, it is not able to fit in the alpha-helices.
=== Comorbid disorders === People with comorbid mental health conditions such as depression, anxiety, attention deficit hyperactivity disorder or post-traumatic stress disorder are more likely to develop substance use disorders.
== Drug interactions == Thiotepa can have various interactions with other medications or therapies that can impact patient safety and treatment efficacy. Aprepitant, a drug that prevents nausea and vomiting that may occur during chemotherapy, inhibits CYP-enzymes, which decrease the metabolism of thiotepa to tepa. Its importance is relatively minor because inhibition itself is small and due to the variability of thiotepa clearance in different individuals. The anti-seizure medication phenytoin induces the CYP3A4 enzyme. This leads to an increased rate of tepa formation from thiotepa, which highly influences its clearance and concentration. Higher local concentrations of the more reactive tepa can potentially induce hepatotoxicity. Additionally, cytotoxic drugs such as thiotepa can reduce the absorption of phenytoin leading to the increased risk of seizures. It is advised to avoid the use of both drugs simultaneously or decrease thiotepa doses. Myelosuppressive/myelotoxic agents such as melphalan, busulfan, treosulfan, and cyclophosphamide, as well as the concurrent use of thiotepa, may increase the risk of hematologic adverse reactions and pulmonary toxicity, as they share similar toxicity profiles. Additionally, the use of live attenuated vaccines (including yellow fever) poses a risk of systemic and potentially fatal infection, with the risk further heightened in patients who are already immunosuppressed due to their underlying disease.
Polymyxins are a group of cyclic non-ribosomal polypeptide (NRPs) which are biosynthesized by bacteria belonging to the genus Paenibacillus. Polymyxins consist of 10 amino acid residues, six of which are L-α,γ-diaminobutyric acid (L-DAB). The DAB residues cause polymyxins to have multiple positively charged groups at physiological pH. Seven amino acid residues form the main cyclic component, while the other three extend from one of the cyclic residues as a linear chain terminating in either 6-methyloctanoic acid or 6-methylheptanoic acid at the N-terminus. During cyclization, residue 10 is bound to the bridging residue 4. The amino acid residues and DAB monomers are generally in the L (levo) configuration, however certain strains such as P. polymyxa PKB1 have been observed to incorporate DAB with the D (dextro) configuration at position 3 producing variations of polymyxin B. Polymyxin M is also known as "mattacin".
== Absolute size-exclusion chromatography == Absolute size-exclusion chromatography (ASEC) is a technique that couples a light scattering instrument, most commonly multi-angle light scattering (MALS) or another form of static light scattering (SLS), but possibly a dynamic light scattering (DLS) instrument, to a size-exclusion chromatography system for absolute molar mass and/or size measurements of proteins and macromolecules as they elute from the chromatography system. The definition of "absolute" in this case is that calibration of retention time on the column with a set of reference standards is not required to obtain molar mass or the hydrodynamic size, often referred to as hydrodynamic diameter (DH in units of nm). Non-ideal column interactions, such as electrostatic or hydrophobic surface interactions that modulate retention time relative to standards, do not impact the final result. Likewise, differences between conformation of the analyte and the standard have no effect on an absolute measurement; for example, with MALS analysis, the molar mass of inherently disordered proteins are characterized accurately even though they elute at much earlier times than globular proteins with the same molar mass, and the same is true of branched polymers which elute late compared to linear reference standards with the same molar mass. Another benefit of ASEC is that the molar mass and/or size is determined at each point in an eluting peak, and therefore indicates homogeneity or polydispersity within the peak.
Sources: en.wikipedia.org
Liljestrand noted that thirteen of the first sixteen nominations that came in mentioned Fleming, but only three mentioned him alone. This time evaluations were made by Liljestrand, Sven Hellerström and Anders Kristenson, who endorsed all three. The Nobel Assembly at the Karolinska Institute considered awarding half to Fleming and one-quarter each to Florey and Chain, but in the end decided to divide it equally three ways. On 25 October 1945, it announced that Fleming, Florey and Chain equally shared the 1945 Nobel Prize in Physiology or Medicine "for the discovery of penicillin and its curative effect in various infectious diseases."
=== Diagnostic criteria === Different criteria are used for diagnosing PMOS, but the (revised) Rotterdam criteria are recommended by clinical guidelines. According to these criteria, an adult woman is diagnosed with PMOS if she meets two out of the following three:
Progesterone converts the endometrium to its secretory stage to prepare the uterus for implantation. At the same time progesterone affects the vaginal epithelium and cervical mucus, making it thick and impenetrable to sperm. Progesterone is anti-mitogenic in endometrial epithelial cells, and as such, mitigates the tropic effects of estrogen. If pregnancy does not occur, progesterone levels will decrease, leading to menstruation. Normal menstrual bleeding is progesterone-withdrawal bleeding. If ovulation does not occur, and the corpus luteum does not develop, levels of progesterone may be low, leading to anovulatory dysfunctional uterine bleeding. During implantation and gestation, progesterone appears to decrease the maternal immune response to allow for the acceptance of the pregnancy. Progesterone decreases contractility of the uterine smooth muscle. This effect contributes to prevention of preterm labor. Studies have shown that in individuals who are pregnant with a single fetus, asymptomatic in the prenatal stage, and at a high risk of giving pre-term birth spontaneously, vaginal progesterone medication has been found to be effective in preventing spontaneous pre-term birth. Individuals who are at a high risk of giving pre-term birth spontaneously are those who have a short cervix of less than 25 mm or have previously given pre-term birth spontaneously. Although pre-term births are generally considered to be less than 37 weeks, these studies found that vaginal progesterone is associated with fewer pre-term births of less than 34 weeks.
=== Intrinsic tryptophan fluorescence wavelength === Utilization of the intrinsic fluorescence properties of tryptophan residues in many proteins forms the basis of nanoDSF. The emission wavelengths of tryptophan residues are dependent on the surrounding chemical environment, notably solvation (see solvatochromism) and therefore differ between folded and unfolded protein, just as with the fluorescence lifetime. Typically, interior tryptophan residues in a more hydrophobic environment exhibit a notable emission red shift from approximately 330 nm to 350 nm upon protein unfolding and exposure to water. Quantification of fluorescence wavelength shifts at various temperature intervals yields a measurement of Tm. Currently there are at least three instruments on the market that can read this shift in wavelength in a high-throughput manner while heating the samples. The advantages and disadvantages are the same as for fluorescence lifetime except that there are more examples in the scientific literature of use. nanoDSF uses the intrinsic fluorescence of tryptophan residues present in many proteins to monitor protein folding and stability. Because tryptophan fluorescence depends on the local chemical environment, protein unfolding exposes buried residues to water and typically shifts the emission maximum from about 330 nm to 350 nm.
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.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.