Everything below concerns RP-HPLC purity. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
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.
Benzyl (Bn) group – Removed by hydrogenolysis p-Methoxybenzyl (PMB) – Removed by hydrogenolysis, more labile than benzyl 3,4-Dimethoxybenzyl (DMPM) – Removed by hydrogenolysis, more labile than p-methoxybenzyl p-Methoxyphenyl (PMP) group – Removed by ammonium cerium(IV) nitrate (CAN)
=== Headache === Amitriptyline is probably effective for the prevention of periodic migraine in adults. Amitriptyline is similar in efficacy to venlafaxine and topiramate but carries a higher burden of adverse effects than topiramate. For many patients, even small doses of amitriptyline are helpful, which may allow for minimization of side effects. Amitriptyline is not significantly different from placebo when used for the prevention of migraine in children. Amitriptyline may reduce the frequency and duration of chronic tension headache, but it is associated with worse adverse effects than mirtazapine. Overall, amitriptyline is recommended for tension headache prophylaxis, along with lifestyle advice, which should include avoidance of analgesia and caffeine.
== Applications == ECM biomaterials are used to promote healing in a number of tissues, especially the skin and tendons. Surgimend, a collagen matrix derived from fetal bovine dermis, can trigger the healing of tendons (which do not heal spontaneously) in the ankle. This intervention can shorten healing time by almost half and allows the patient to return to full activity much sooner. Open wounds, like tendons, do not spontaneously heal and can persist for long stretches of time. When ECM biomaterials are added in multiple layers to the ulcer, the wound begins to close quickly and generates host tissue. Although preliminary studies seem promising, little information is available on the success of and direct comparisons between different ECM biomaterial devices in human trials. Alloderm, an acellular dermis derived from the skin of donated cadavers, is used in reconstructive and dental surgeries. In gingival grafts, the acellular dermis is an alternative to tissue cut from the palate of the patient's mouth. It has also been used for abdominal hernia repair, and to rebuild resected turbinates in the treatment of empty nose syndrome. Alloderm and other acellular dermal matrices are used routinely in implant based breast reconstruction after mastectomy for improved soft tissue coverage and thus decrease the risk of visible rippling, capsular contraction, implant malposition, bottoming out and implant exposure.
==== On Natural Amino Acids ==== Rh-catalyzed Trp and Cys alkylation Using in situ generated RhII-carbenoid by activation of vinyl-substituted diazo compounds with Rh2(OAc)4, tryptophans and cysteines were shown to be selectively alkylated in aqueous media. However, this method is limited to surface tryptophans and cysteines possibly because of steric constraints.
Sources: en.wikipedia.org
=== Temperature === Temperature is another interesting parameter to discuss since protein solubility is a function of temperature. In protein crystallization, manipulation of temperature to yield successful crystals is one common strategy. Unlike pH, temperature of different components of the crystallography experiments could impact the final results such as temperature of buffer preparation, temperature of the actual crystallization experiment, etc.
== Legislative impact == In February 2025, West Virginia lawmakers introduced House Bill 2789, also known as The Michael Brandon Cochran Act. The bill mandates intensive care units to conduct C-peptide insulin tests for unconscious patients or those presenting with hypoglycemia and blood glucose levels below 49 mg/dl. The legislation aims to prevent similar cases of insulin misuse.
== Publications == The OECD publishes books, reports, statistics, working papers, and reference materials. All titles and databases published since 1998 can be accessed via OECD.org. The OECD Library & Archives collection dates from 1947, including records from the Committee for European Economic Co-operation (CEEC) and the Organisation for European Economic Co-operation (OEEC), predecessors of today's OECD. External researchers can consult OECD publications and archival material on the OECD premises by appointment.
===== Strontium/calcium ratio anomaly ===== Time can be attributed to coral geochemistry anomalies by correlating strontium/calcium minimums with sea surface temperature (SST) maximums to data collected from NINO 3.4 SSTA.
Tiapride is a drug that selectively blocks D2 and D3 dopamine receptors in the brain. It is used to treat a variety of neurological and psychiatric disorders including dyskinesia, alcohol withdrawal syndrome, negative symptoms of psychosis, and agitation and aggression in the elderly. A derivative of benzamide, tiapride is chemically and functionally similar to other benzamide antipsychotics such as sulpiride and amisulpride known for their dopamine antagonist effects.
Sources: en.wikipedia.org
In skeletal muscles, muscle spindles convey information about the degree of muscle length and stretch to the central nervous system to assist in maintaining posture and joint position. The sense of where our bodies are in space is called proprioception, the perception of body awareness, the "unconscious" awareness of where the various regions of the body are located at any one time. Several areas in the brain coordinate movement and position with the feedback information gained from proprioception. The cerebellum and red nucleus in particular continuously sample position against movement and make minor corrections to assure smooth motion.
=== Radiation therapy === Radiation therapy is usually reserved for people who have tumours remaining after surgery. These people often also receive medication to lower GH levels. Radiation therapy is given in divided doses over four to six weeks. This treatment lowers GH levels by about 50 percent over 2 to 5 years. People monitored for more than 5 years show significant further improvement. Radiation therapy causes a gradual loss of production of other pituitary hormones with time. Loss of vision and brain injury, which have been reported, are very rare complications of radiation treatments.
After nearly becoming extinct in the 1940s and the 1950s, the Liberal Party revived its fortunes somewhat under the leadership of Jo Grimond in the 1960s by positioning itself as a radical centrist, non-socialist alternative to the Conservative and Labour Party governments of the time.
=== Xie === In contrast to the majority of other functional entities, xuè or xiě (血, "blood") is correlated with a physical form – the red liquid running in the blood vessels. Its concept is, nevertheless, defined by its functions: nourishing all parts and tissues of the body, safeguarding an adequate degree of moisture, and sustaining and soothing both consciousness and sleep. Typical symptoms of a lack of xiě (usually termed "blood vacuity" [血虚; xiě xū]) are described as: Pale-white or withered-yellow complexion, dizziness, flowery vision, palpitations, insomnia, numbness of the extremities; pale tongue; "fine" pulse.
== Side effects == Degarelix is commonly associated with hormonal side effects such as hot flashes and weight gain. Due to its mode of administration (subcutaneous injection), degarelix is also associated with injection-site reactions such as injection-site pain, erythema or swelling. Injection-site reactions are usually mild or moderate in intensity and occur predominantly after the first dose, decreasing in frequency thereafter. Less common: Anemia. Diarrhea, nausea. Hyperhidrosis including night sweats, rash. Gynecomastia, testicular atrophy, erectile dysfunction. Increased transaminases. Musculoskeletal pain and discomfort. Dizziness, headache. Insomnia. Weight gain. Chills, fever, fatigue, flu-like illness.
Sources: en.wikipedia.org
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
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.