If you have been reading about lyophilized and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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.
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.
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.
| 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 |
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
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.
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 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.
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.
=== Miscellaneous === Galactogogues such as the peripherally selective D2 receptor antagonist and prolactin releaser domperidone can be used to induce lactation in transgender women who wish to breastfeed. An extended period of combined estrogen and progestogen therapy is necessary to mature the lobuloalveolar tissue of the breasts before this can be successful. There are several published reports of lactation and/or breastfeeding in transgender women. The World Professional Association for Transgender Health (WPATH) Standards of Care for the Health of Transgender and Gender Diverse People Version 8 (SOC8), released in September 2022, recommends against therapeutic strategies including supraphysiological estradiol levels (>200 pg/mL), use of progesterone (including rectal progesterone), use of bicalutamide, and monitoring of the ratio of estrone to estradiol. This is due to lack of data to support these approaches in transfeminine people as well as potential risks. The WPATH SOC8 also recommends against the use of 5α-reductase inhibitors such as finasteride in transfeminine people.
=== In print === Acererak is the final boss of the classic Dungeons and Dragons adventure module Tomb of Horrors; Acererak was also featured as the guardian of the Copper Key in the book Ready Player One by Ernest Cline. In the webcomic The Order of the Stick, the main villain Xykon is a lich. In the Harry Potter series, the main antagonist Voldemort commands armies of undead inferi and uses magical devices called horcruxes to store fragments of his soul in order to allow him to resurrect himself in the event that his body dies.
== Natural resources == The mineral form of potassium sulfate, arcanite, is relatively rare. Natural resources of potassium sulfate are minerals abundant in the Stassfurt salt. These are cocrystallizations of potassium sulfate and sulfates of magnesium, calcium, and sodium. Relevant minerals are:
Sources: en.wikipedia.org
== Medical use == Cyanocobalamin is usually prescribed after surgical removal of part or all of the stomach or intestine to ensure adequate serum levels of vitamin B12. It is also used to treat pernicious anemia, vitamin B12 deficiency (due to low intake from food or inability to absorb due to genetic or other factors), thyrotoxicosis, hemorrhage, malignancy, liver disease and kidney disease. Cyanocobalamin injections are often prescribed to gastric bypass patients who have had part of their small intestine bypassed, making it difficult for B12 to be acquired via food or vitamins. Cyanocobalamin is also used to perform the Schilling test to check ability to absorb vitamin B12. Cyanocobalamin is also produced in the body (and then excreted via urine) after intravenous hydroxycobalamin is used to treat cyanide poisoning.
In contrast, FSL Kode constructs usually use specifically selected peptide fragments (up to 40 amino acids), thereby overcoming cross-reactivity with microbial sequences, and allowing for the use of undiluted serum (which increases sensitivity). The F component can be further enhanced by presentation of it in multimeric formats and with specific spacing. The four types of multimeric format include linear repeating units, linear repeating units with spacing, clusters, and branching (Fig. 4).
=== Pharmacodynamics === (+)-JRT is highly selective for a subset of serotonin receptors and does not bind to various dopamine, adrenergic, or histamine receptors, which is in contrast to LSD. It shows high affinity for the serotonin 5-HT2 receptors, with Ki values ranging from 2.0 to 184 nM. The drug is a potent partial agonist of the serotonin 5-HT2A and 5-HT2B receptors (EmaxTooltip maximal efficacy = 33–81% and 48–51%, respectively) and a full agonist of the serotonin 5-HT2C receptor (Emax = 89%). It is also an agonist of the serotonin 5-HT1A and 5-HT7 receptors, an antagonist of the serotonin 5-HT5A and 5-HT7 receptors, and a ligand of the serotonin 5-HT6 receptor. (+)-JRT does not have significant affinity for the serotonin 5-HT1B or 5-HT3 receptors, whereas its affinities for the other serotonin 5-HT1 receptors and the serotonin 5-HT4 receptor were not reported. The drug is 4.4- to 180-fold less potent than LSD as a serotonin 5-HT2A receptor agonist in vitro (EC50Tooltip half-maximal effective concentration = 0.4–90 nM vs. 0.09–0.5 nM, respectively) and is less efficacious than LSD in activating the receptor (Emax = 33% vs. 44–63%, respectively). It has been found to dissociate from the serotonin 5-HT2A receptor approximately 10-fold more quickly than LSD. (+)-JRT produces the head-twitch response (HTR), a behavioral proxy of psychedelic effects, in rodents, and hence would be expected to be hallucinogenic in humans. However, the drug shows a reduced HTR compared to LSD, producing less than half the maximal number of head twitches.
A systematic review and meta-analysis has shown that cabergoline and quinagolide are more effective in the treatment of hyperprolactinemia compared to bromocriptine, this is because evidence had suggested fewer side effects, rapid titration and offers better dosing interval in medication like quinagolide compared to bromocriptine. Similar studies have been conducted regarding the safety and efficacy of dopamine agonists. According to SUCRA (Surface Under the Cumulative Ranking) and SMAA (Stochastic Multicriteria Acceptability Analysis), quinagolide was found to be the best treatment for women since it can help reduce menstrual irregularities, in addition bromocriptine was shown to be more effective in the treatment for galactorrhea (breast milk production unrelated to pregnancy), and cabergoline was the safest medication as it did not show any alarming side effects. Other dopamine agonists that have been used less commonly to suppress prolactin include dihydroergocryptine, ergoloid, lisuride, metergoline, pergolide, and terguride. If the prolactinoma does not initially respond to dopamine agonist therapy, such that prolactin levels are still high or the tumor is not shrinking as expected, the dose of the dopamine agonist can be increased in a stepwise fashion to the maximum tolerated dose. Another option is to consider switching between dopamine agonists. The prolactinoma can be resistant to bromocriptine but respond well to cabergoline or other dopamine agonists, and vice versa.
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.
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.