The short version of lyophilised powder fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-07-02 and is reviewed periodically as new material appears.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
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.
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.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
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.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
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.
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.
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.
=== March === 1 March – Statistics released by the Scottish Government indicate Scotland's economy grew by 0.1% during the three months from October–December 2022. 2 March – Minister for Transport Jenny Gilruth announces plans to nationalise the overnight Caledonian Sleeper train service that links London with several locations in Scotland, taking effect from 25 June. 3 March The Educational Institute of Scotland and other teaching unions call off a planned 20 days of rolling strikes scheduled to begin on 13 March after receiving an improved pay offer from the Scottish Government, worth 14.6% over 28 months. The proposals will now be put to a ballot. Loganair announces it will suspend flights between Inverness Airport and some island airports for at least six weeks from 17 March because of industrial action scheduled to begin at Highland and Islands Airports Limited. 6 March – BBC News reports that the Scottish Prison Service is to be investigated for corporate manslaughter over the death of Allan Marshall, a prisoner at HMP Edinburgh, who died after being restrained by 13 prison officers in 2015. 7 March – STV hosts the first televised debate of the Scottish National Party leadership election. 10 March – Members of Scotland's largest teaching union, the Educational Institute of Scotland, vote to accept a pay deal from the Scottish Government that will end ongoing strikes in schools. 13 March – Voting opens in the Scottish National Party leadership election.
=== Purity and purification === TLC helps show the purity of a sample. A pure sample should only contain one spot by TLC. TLC is also useful for small-scale purification. Because the separated compounds will be on different areas of the plate, a scientist can scrape off the stationary phase particles containing the desired compound and dissolve them into an appropriate solvent. Once all the compound dissolves in the solvent, they filter out the silica particles, then evaporate the solvent to isolate the product. Big preparative TLC plates with thick silica gel coatings can separate more than 100 mg of material. TLC is useful for larger-scale purification and isolation to quickly test solvent mixtures before running flash column chromatography on a large batch of impure material. A compound elutes from a column when the amount of solvent collected is equal to 1/RF. The eluent from flash column chromatography gets collected across several containers (for example, test tubes) called fractions. TLC helps show which fractions contain impurities and which contain pure compound. Furthermore, two-dimensional TLC can help check if a compound is stable on a particular stationary phase. This test requires two runs on a square-shaped TLC plate. The plate is rotated by 90º before the second run. If the target compound appears on the diagonal of the square, it is stable on the chosen stationary phase. Otherwise, it is decomposing on the plate. If this is the case, an alternative stationary phase may prevent this decomposition.
He was also believed to take refuge in Morocco and Dubai. On 26 July 2015, Houssine Ait Soussan was arrested by the Moroccan police in the port of Tangier with false documents. A few days after his arrest, two searches took place in the apartments where he stayed at in Marrakech. At least 10 false Dutch, French and Moroccan identity documents were found, alongside 34 luxury watches, 10 phones, two tablets, 178,570 dirhams and €700. Houssine Ait Soussan was eventually released after 3 months by the Moroccan authorities. The Dutch and Belgian authorities believe that Houssine Ait Soussan is currently running his operations while hiding out in Morocco.
=== Aneuploidy === Sex chromosomes Analysis of maternal serum cffDNA by high-throughput sequencing can detect common fetal sex chromosome aneuploidies such as Turner's syndrome, Klinefelter's syndrome and triple X syndrome but the procedure's positive predictive value is low.
RGFP966 is a histone deacetylase (HDAC) inhibitor, specifically acting as a highly selective HDAC3 inhibitor, with an IC50Tooltip half-maximal inhibitory concentration of 80 nM and no inhibition of other HDACs at concentrations of up to 15,000 nM or 20,000 nM. It enhances cognition, memory, and learning in rodents. The drug reverses age-related impairments in memory updating in rodents. In addition, it has been found to facilitate the extinction of drug-seeking behavior in a manner refractory to reinstatement in rodents. Conversely, unlike the pan-class I HDAC inhibitor RGFP963, RGFP966 failed to enhance consolidation of cued fear extinction in rodents, suggesting that HDAC1 and/or HDAC2 may be involved in this instead. Also unlike pan-class I HDAC inhibitors, which can enhance synaptogenesis, RGFP966 showed minimal effect in this regard. The drug increases brain-derived neurotrophic factor (BDNF) expression. Knockdown of HDAC2 and knockdown of HDAC3 have been found to increase BDNF expression, whereas knockdown of other HDACs did not do so. RGFP966 produces anti-inflammatory effects. It shows antidepressant-like effects against neuroinflammation-induced depression in rodents. Similarly to butyric acid (butyrate), RGFP966 ameliorates sleep deprivation-induced intestinal mucosa-induced damage in rodents. RGFP966 has neuroprotective and neurorestorative effects in preclinical research.
Sources: en.wikipedia.org
In 1775, the Continental Congress determined a ration that included either one pound (450 g) of beef, three-quarters pound (340 g) of pork, or one pound (450 g) of salted fish per day, as well as one pound (450 g) of flour or bread per day, one pint of milk per day, one quart of spruce beer or cider per day, three pounds (1.4 kg) of peas or beans per week, one pint of rice per week, and a small amount of molasses. However, in reality, the Continental Army had difficulties supplying its units. Congress lacked the authority to raise sufficient taxes and transportation and other supply issues compounded the problem. In reality, soldiers might receive some flour and perhaps a small amount of meat or fish. In order to preserve the food, meat was often salted and the flour would often be baked into hard biscuits. As these rations had hardly any nutrients, a weekly ration of vinegar or sauerkraut was eventually added to try to prevent scurvy, but this was insufficient. Sometimes days would pass between rations. Soldiers had to resort to foraging, with those who understood the local vegetation being able to find food in woods around the camps. At Valley Forge, watercress and sorrel were sometimes foraged to provide the troops with some vegetables. Soldiers at times had to hunt whatever animals they could find and beg civilians for food. They also bought food when possible, but this proved difficult as the Continental Army mostly paid in promissory notes which were widely distrusted and many soldiers had little goods or money to trade.
== Challenges with peptide identification == Peptides that are degenerate (shared by two or more proteins in the database) makes it difficult to unambiguously identify the protein to which they belong. Additionally, some proteome samples of vertebrates have a large number of paralogs, and alternative splicing in higher eukaryotes can result in many identical protein subsequences. Moreover, many proteins are naturally (co- or post-translational) or artificially (sample preparation artefacts) modified. This further challenges the identification of the peptide sequence by means of conventional database matching approaches. Together with peptide fragmentation spectra of poor quality or high complexity (due to co-isolation or sensitivity limitations), this leaves in a conventional shotgun proteomics experiment many sequencing spectra unidentified.
==== Toxicity ==== Cardiac troponin T and I can be used to monitor drug and toxin-induced cardiomyocyte toxicity. . Chemotherapy agents can exert toxic effects on the heart (examples include anthracycline, cyclophosphamide, 5-fluorouracil, and cisplatin). Several toxins and venoms can also lead to heart muscle injury (scorpion venom, snake venom, and venom from jellyfish and centipedes). Carbon monoxide poisoning or cyanide poisoning can also be accompanied by the release of troponins due to hypoxic cardiotoxic effects. Cardiac injury occurs in about one-third of severe CO poisoning cases, and troponin screening is appropriate in these patients.
In December 2023, ActionAid reported that there was little water for washing and some shelters only had one shower for every 700 individuals and one toilet for every 150. UNICEF announced on 7 March 2024 that they were distributing wellbeing kits to adolescent girls in Rafah, who reported being unable to "shower more than once a week. The shelters are crowded with people, and there is little water. It is difficult to maintain personal hygiene". It was reported in late February 2024 that there were 690,000 menstruating women and children in Gaza, that have limited access to menstrual hygiene supplies. Some women and children have utilized period blocking pills, but those can be hard to find and many are unable to take them for medical reasons. One girl sheltering in a UNRWA school in Maghazi told reporters that she had begun washing used pads to reuse them, while another indicated that due to the stress of the war she had been having her period more often, about twice a month. A mom of five daughters told reporters that they were all utilizing Pampers diapers for their periods, and had to cut the diapers in half due to costs while others have utilized rags, old clothes, towels or corners of tents causing chafing and skin infections. In June 2024, children suffered from intestinal infections and hepatitis C or A, due to the destruction of Gaza's water supply and sanitation systems.
The brown bear has a hump between its shoulders, a distinction from other bear species. This hump is formed by large muscles, allowing for a wide range of motion, which the bear mainly uses to put pressure on the soil as it digs for food. The bison also has a hump between its shoulders, made almost entirely of muscle and supported by long skeletal spines. The bison hump's purpose is to hold up the animal's large head, and also enables the animal to use its head as a snow shovel in the winter, swinging it side to side with its hump muscles. Such foraging behavior sets the bison apart from other ungulates, which typically use their feet to scrape away snow. Moose, similarly, have a shoulder hump of muscle that is necessary to hold up their large head and, in males, antlers.
Sources: en.wikipedia.org
This period is also marked by the appearance of the self-portraits of painters in long tunics and highboots armed with short daggers, such as the painter of the Cave of the Statues or the several painters of the "Cave of the Painters", with often their own identifying labels in Sanskrit. The clothing style and type of these painters has often been described as Sasanian, but has recently been proposed as being rather Hephthalite, due to the similarities with the Hephthalite figures in Dilberjin Tepe, Balalyk Tepe or Bamiyan, and because the Hepthalites did control the Tarim Basin for nearly a century around this time period.
Weapon-grade uranium obtained from nuclear weapons is diluted with uranium-238 and reused as fuel for nuclear reactors. Spent nuclear fuel forms radioactive waste, which mostly consists of uranium-238 and poses a significant threat to health and to the environment.
In May 2019, in a milestone effort, researchers reported the creation of a new synthetic (possibly artificial) form of viable life, a variant of the bacteria Escherichia coli, by reducing the natural number of 64 codons in the bacterial genome to 59 codons instead, in order to encode 20 amino acids. In 2017, the international Build-a-Cell large-scale open-source research collaboration for the construction of synthetic living cells was started, followed by national synthetic cell organizations in several countries, including FabriCell, MaxSynBio and BaSyC. The European synthetic cell efforts were unified in 2019 as SynCellEU initiative. In 2023, researchers were able to create the first synthetically made human embryos derived from stem cells.
=== Mono(ADP-ribosyl)ation === Mono(ADP-ribosyl)transferases commonly catalyze the addition of ADP-ribose to arginine side chains using a highly conserved R-S-EXE motif of the enzyme. The reaction proceeds by breaking the bond between nicotinamide and ribose to form an oxonium ion. Next, the arginine side chain of the target protein then acts a nucleophile, attacking the electrophilic carbon adjacent to the oxonium ion. In order for this step to occur, the arginine nucleophile is deprotonated by a glutamate residue on the catalyzing enzyme. Another conserved glutamate residue forms a hydrogen bond with one of the hydroxyl groups on the ribose chain to further facilitate this nucleophilic attack. As a result of the cleavage reaction, nicotinamide is released. The modification can be reversed by (ADP-ribosyl)hydrolases, which cleave the N-glycosidic bond between arginine and ribose to release ADP-ribose and unmodified protein; NAD+ is not restored by the reverse reaction.
== Mechanism of action == Isoniazid is a prodrug that inhibits the formation of the mycobacterial cell wall. Isoniazid must be activated by KatG, a bacterial catalase-peroxidase enzyme in Mycobacterium tuberculosis. KatG catalyzes the formation of the isonicotinic acyl radical, which spontaneously couples with NADH to form the nicotinoyl-NAD adduct. This complex binds tightly to the enoyl-acyl carrier protein reductase InhA, thereby blocking the natural enoyl-AcpM substrate and the action of fatty acid synthase. This process inhibits the synthesis of mycolic acids, which are required components of the mycobacterial cell wall. A range of radicals are produced by KatG activation of isoniazid, including nitric oxide, which has also been shown to be important in the action of another antimycobacterial prodrug pretomanid.
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.