This is a working overview of Research chemical, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-27 and is reviewed periodically as new material appears.
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.
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.
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.
| 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.
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.
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.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
Unlike TTP, no deficient ADAMTS13 activity nor anti-ADAMTS13 antibody was found indicating a thrombotic microangiopathy of different underlying cause. If IV Opana abuse is acknowledged, supportive care, instead of therapeutic plasma exchange could be considered. In January 2015, the first HIV outbreak linked to abuse of prescription opioid drugs was identified by the Indiana State Department of Health (ISDH), in the small, rural community of Scott County in southeastern Indiana. ISDH launched an investigation into this HIV outbreak when 11 individuals were confirmed positive for HIV with ties tracing back to the same community. Three months into this investigation, ISDH diagnosed a total of 135 people with HIV, with the numbers still increasing. The cause of this outbreak has been linked to the sharing of needles between opioid abusers, which in some cases, involves sharing needles with up to nine different partners. In late March 2015, reports indicated Austin, Indiana, was the center of an outbreak of HIV caused by oxymorphone use as an injectable recreational drug. The outbreak required emergency action by state officials. The NPR podcast "embedded" episode of 31 March 2016 was an in-depth account of a visit to oxymorphone abusers in Austin, Indiana. In 2016, the street price of oxymorphone was reported to be US$140. The common opioid of abuse in this outbreak has been identified as Opana ER, a time-released oxymorphone pain killer formulated to be resistant to crushing, manufactured by Endo Pharmaceuticals.
== Adverse effects == The most common side effects include nausea (feeling sick), vomiting, constipation, loss of appetite, alopecia (hair loss), headache, fatigue (tiredness), convulsions (fits), rash, neutropenia or lymphopenia (low white-blood-cell counts), and thrombocytopenia (low blood platelet counts). People receiving the solution for infusion may also have injection-site reactions, such as pain, irritation, itching, warmth, swelling and redness, as well as bruising.
Carbohydrate catabolism Citric acid cycle Cori cycle Fermentation (biochemistry) Gluconeogenesis Glycolytic oscillation Glycogenoses (glycogen storage diseases) Inborn errors of carbohydrate metabolism Pentose phosphate pathway Pyruvate decarboxylation Triose kinase
== Toxicity == A subacute rodent NOAEL of 43 μg/kg body weight as well as genotoxicity studies were primarily the cause for setting limits for patulin exposure, although a range of other types of toxicity also exist. While not a particularly potent toxin, patulin is genotoxic. Some theorize that it may be a carcinogen, although animal studies have remained inconclusive. Patulin has shown antimicrobial properties against some microorganisms. Several countries have instituted patulin restrictions in apple products. The World Health Organization recommends a maximum concentration of 50 μg/L in apple juice. In the European Union, the limit is also set at 50 micrograms per kilogram (μg/kg) in apple juice and cider, at 25 μg/kg in solid apple products, and at 10 μg/kg in products for infants and young children. These limits came into force on 1 November 2003.
Sources: en.wikipedia.org
Since the ligand is responsible for cellular interaction, it is chosen for the application depending on the target site. The target site contains binding sites that the ligand targets to deliver the LTL to the desired area. Favorable target site characteristics are determined by what is commonly expressed by tissues of the pathology of interest. Determinants can include histones, basement membrane fibrinogen, selectins, adhesion molecules, and other ligand targets. For example, in some human cancer tumors such as ovarian carcinomas, folate is over-expressed. LTLs for targeting cancer often use a ligand that targets this over-expression of folate to localize drug delivery to the desired area. The tumor microenvironment of solid tumor cancers is also a unique targeting site. Tumor endothelial cells are important for angiogenesis, which is key to tumor growth; therefore, using LTLs to target these cells can limit the growth and vascularization of a tumor.
Like DNA, RNA can store and replicate genetic information. Although RNA is considerably more fragile than DNA, some ancient RNAs may have evolved the ability to methylate other RNAs to protect them. The concurrent formation of all four RNA building blocks further strengthens the hypothesis. Enzymes made of RNA (ribozymes) can catalyze (start or accelerate) chemical reactions that are critical for life, so it is conceivable that in an RNA world, ribozymes might have preceded enzymes made of protein. Many coenzymes that have fundamental roles in cellular life, such as acetyl-CoA, NADH, FADH, and F420, are structurally strikingly similar to RNA and so may be surviving remnants of covalently bound coenzymes in an RNA world. One of the most critical components of cells, the ribosome, is composed primarily of RNA. Although alternative chemical paths to life have been proposed, and RNA-based life may not have been the first life to exist, the RNA world hypothesis seems to be the most favored abiogenesis paradigm. However, even proponents agree that there is still not conclusive evidence to completely falsify other paradigms and hypotheses. Regardless of its plausibility in a prebiotic scenario, the RNA world can serve as a model system for studying the origin of life. If the RNA world existed, it was probably followed by an age characterized by the evolution of ribonucleoproteins (RNP world), which in turn ushered in the era of DNA and longer proteins. DNA has greater stability and durability than RNA, which may explain why it became the predominant information storage molecule.
This is relevant for enzymes like pepsin that are active in acidic environments such as the mammalian stomach and lysosomes, but does not significantly apply to intracellular enzymes. In highly basic conditions (pH greater than 10, not normally seen in physiological conditions), the ammonio group is deprotonated to give NH2−CHR−CO−2. Although various definitions of acids and bases are used in chemistry, the only one that is useful for chemistry in aqueous solution is that of Brønsted: an acid is a species that can donate a proton to another species, and a base is one that can accept a proton. This criterion is used to label the groups in the above illustration. The carboxylate side chains of aspartate and glutamate residues are the principal Brønsted bases in proteins. Likewise, lysine, tyrosine and cysteine will typically act as a Brønsted acid. Histidine under these conditions can act both as a Brønsted acid and a base.
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.