This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-05 and is reviewed periodically as new material appears.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
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.
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.
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 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.
Cholesterol ratio: This ratio compares the levels of LDL to HDL. Trans fat behaves like saturated fat by raising the level of LDL, but, unlike saturated fat, it has the additional effect of decreasing levels of HDL. The net increase in LDL/HDL ratio with trans fat is approximately double that due to saturated fat. (Higher ratios are worse.) One randomized crossover study published in 2003 comparing the effect of eating a meal on blood lipids of (relatively) cis and trans fat rich meals showed that cholesteryl ester transfer (CET) was 28% higher after the trans meal than after the cis meal and that lipoprotein concentrations were enriched in apolipoprotein(a) after the trans meals. C-reactive protein (CRP): A study of over 700 nurses showed that those in the highest quartile of trans fat consumption had blood levels of CRP that were 73% higher than those in the lowest quartile.
A 2021 deep-learning algorithms-based software called AlphaFold, developed by Google's DeepMind, released predicted structures for hundreds of millions of proteins in the AlphaFold protein structure database.
== Description == Spelt is a species of Triticum, a large stout grass similar to bread wheat. Its flowering spike is slenderer than that of bread wheat; when ripe, it bends somewhat from the vertical. The spike is roughly four-edged. The axis of the spike is brittle and divided into segments; it shatters into separate segments when fully ripe. Spelt differs from bread wheat in that each seed (a caryopsis, botanically a fruit with its wall fused to the single seed inside) stays fully encapsulated by its husk.
=== Competitive and ecological roles === Beyond these interactions, Xanthoria parietina often overgrows other epilithic lichens without affecting their photobionts. It also supports microbial communities beneath its thallus, likely benefiting from microhabitats created by its attachment structures. In addition, Xanthoria parietina plays a role in biogeochemical cycling by promoting rock weathering through hyphal penetration and adhesion. Its interactions with minerals such as quartz, feldspar, and muscovite contribute to mineral breakdown, particularly in carbonate-rich substrates. Finally, the lichen competes with other foliose lichens. In experimental settings, it showed competitive equivalence with Parmelia caperata but was overgrown by Parmelia saxatilis under some conditions. In three-species mixtures, however, X. parietina often gained a competitive advantage—possibly due to its tolerance for elevated nitrogen levels. Its ability to thrive in nutrient-rich environments may allow it to outcompete acidophytic species in habitats influenced by agricultural or atmospheric nitrogen inputs. When competing with other lichens, X. parietina typically forms codominant relationships rather than completely displacing other species, particularly in early colonization stages. Field studies show that when X. parietina thalli border upon other lichens such as Physcia species, neither distinctly overgrows the other, but rather their marginal lobes intermingle. The frequent co-occurrence of X. parietina with grey-colored Physcia species may represent more than simple cohabitation.
== Further reading == Brayden DJ (November 2022). "Localised Delivery of Macromolecules to the Large Intestine: Translation to Clinical Trials". BioDrugs. 36 (6): 687–700. doi:10.1007/s40259-022-00562-6. PMID 36282433. S2CID 253109130.</ref> Fourie A, Cheng X, Chang L, Greving C, Patrick A, Knight B, et al. (October 2023). "S1028 Characterization of a First-in-Class Oral Therapy Selectively Targeting the IL-23 Pathway". American Journal of Gastroenterology. 118 (10S): S781. doi:10.14309/01.ajg.0000953752.29003.56. Ghusn W, Gala K, Rahme SJ, Salame M, Mrad R, Abboud DM, et al. (October 2023). "S1029 Disparities in Age, Sex, Race, and Ethnicity in Clinical Trials Focused on Inflammatory Bowel Disease in the United States". American Journal of Gastroenterology. 118 (10S): S781–S782. doi:10.14309/01.ajg.0000953756.85659.9e. Rusiñol L, Carmona-Rocha E, Puig L (3 July 2023). "Psoriasis: a focus on upcoming oral formulations". Expert Opinion on Investigational Drugs. 32 (7): 583–600. doi:10.1080/13543784.2023.2242767. PMID 37507233. S2CID 260286273.
Sources: en.wikipedia.org
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=== Gómez, France 1998 and the end of the cycle (1995–1999) === Hernán Darío Gómez, known as El Bolillo, replaced Maturana in 1995. Colombia lost 2–0 to the hosts Uruguay in the semi-finals of the 1995 Copa América before beating the United States 4–1 in Maldonado to take third place, Wilmer Cabrera, Valderrama, Asprilla and Rincón all scoring. Two years later they were eliminated 2–1 by the hosts Bolivia in the quarter-finals of the 1997 Copa América. Colombia reached the 1998 FIFA World Cup by finishing third in the first CONMEBOL qualifying tournament contested as a single home-and-away league, taking 28 points from sixteen matches — two behind Argentina and one behind Paraguay — with Asprilla their leading scorer on seven goals, including a hat-trick in a 4–1 win over Chile in Barranquilla. Drawn in Group G with Tunisia, England and Romania, they lost 1–0 to Romania, beat Tunisia 1–0, and were eliminated on 26 June by England at the Stade Bollaert-Delelis in Lens. Darren Anderton volleyed England ahead in the 20th minute and David Beckham curled in a free kick from some 30 yards nine minutes later for his first international goal, Faryd Mondragón keeping the margin to 2–0 thereafter.
==== Molecular toxicology ==== The paradigm of toxicological assessment of benzene is shifting towards the domain of molecular toxicology as it allows understanding of fundamental biological mechanisms in a better way. Glutathione seems to play an important role by protecting against benzene-induced DNA breaks and it is being identified as a new biomarker for exposure and effect. Benzene causes chromosomal aberrations in the peripheral blood leukocytes and bone marrow explaining the higher incidence of leukemia and multiple myeloma caused by chronic exposure. These aberrations can be monitored using fluorescent in situ hybridization (FISH) with DNA probes to assess the effects of benzene along with the hematological tests as markers of hematotoxicity. Benzene metabolism involves enzymes coded for by polymorphic genes. Studies have shown that genotype at these loci may influence susceptibility to the toxic effects of benzene exposure. Individuals carrying variant of NAD(P)H:quinone oxidoreductase 1 (NQO1), microsomal epoxide hydrolase (EPHX) and deletion of the glutathione S-transferase T1 (GSTT1) showed a greater frequency of DNA single-stranded breaks.
=== Anxiety === Anxiety can impair hippocampus function which increases risk of depression and dementia. Anxiolytic effects were observed in animal models post-intranasal delivery of a loaded polymeric nanoparticles. Another study indicated intranasal delivery of neuropeptide Y lowered anxiety in rats.
Nipple pain is a common symptom of pain at the nipple that occurs in women during breastfeeding after childbirth. The pain shows the highest intensity during the third to the seventh day postpartum and becomes most severe on the third day postpartum. Nipple pain can result from many conditions. Early nipple pain in breastfeeding is usually caused by improper positioning and latch while breastfeeding. Other causes may include blocked milk ducts, tongue-tie, cracked nipples and nipple infections by yeasts, bacteria or viruses. Complications in nursing women involve an increase in nipple sensitivity or breast engorgement, leading to mastitis and subsequent pain. Common diagnostic approaches include quantifying pain by the numerical rating scale (NRS) and maternal breast or infant mouth examinations. Nipple pain may hinder breastfeeding and is the most common reason for early weaning. General management such as positioning and latch adjustment and thermal intervention can be administered for pain alleviation. Appropriate treatment of nipple pain is given based on the underlying cause.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.