Pro-Gly-Pro is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-12-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
| 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 |
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
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.
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.
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.
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.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
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.
That promise is null and void if Zverev – and the media – isn't willing to be honest." At the beginning of the 2024 Australian Open, a court official announced that Zverev was scheduled to stand trial before the Tiergarten District Court in Berlin. The timing of the announcement, combined with Zverev's semifinal run at the tournament, brought heightened interest in and scrutiny of the allegations from both the press and the public. The trial began on 31 May 2024. On 7 June 2024, the third day of the trial, the judge agreed to a request by the public prosecution office, endorsed by the alleged victim, to provisionally terminate the proceedings subject to the condition that Zverev pay €200,000, of which €150,000 would go to the German State Treasury and €50,000 to charitable organizations. The trial therefore concluded without a finding of guilt. The prosecutor's request to terminate the proceedings followed an out-of-court agreement between Zverev and the alleged victim, the terms of which were not disclosed. According to his counsel, Zverev entered into the agreement "to put a quick end to the proceedings – above all in the interest of their child", emphasizing that the agreement "includes no determination or admission of guilt".
Cossack relations with the Tsardom of Russia were varied from the outset. At times they supported Russian military operations, at other times they rebelled against the central power. After one such uprising at the end of the 18th century, Russian forces destroyed the Zaporozhian Host. Many of the Cossacks who had remained loyal to the Russian Monarch and continued their service later moved to the Kuban. Others, choosing to continue a mercenary role, escaped control in the large Danube Delta. The service of the Cossacks in the Napoleonic wars led them to be celebrated as Russian folk heroes, and throughout the 19th century a "powerful myth" was promoted by the government that portrayed the Cossacks as having a special and unique bond to the Emperor. This image of the Cossacks as ultra-patriotic defenders of not only Russia, but also of the House of Romanov was embraced by many ordinary Cossacks, making them into a force for conservatism. By the 19th century, the Russian Empire had annexed the territory of the Cossack Hosts, and controlled them by providing privileges for their service such as exemption from taxation and allowing them to own the land they farmed. At this time, the Cossacks served as military forces in many wars conducted by the Russian Empire. Cossacks were considered excellent for scouting and reconnaissance duties, and for ambushes. Their tactics in open battle were generally inferior to those of regular soldiers, such as the Dragoons.
In the early months of the pandemic, there were 96,000 confirmed cases of infection in mainland China. While the proportion of infections that result in confirmed cases or progress to diagnosable disease was unclear at the time, one mathematical model estimated that 75,815 people were infected on 25 January 2020 in Wuhan alone, at a time when the number of confirmed cases worldwide was only 2,015. Before 24 February 2020, over 95% of all deaths from COVID-19 worldwide had occurred in Hubei province, where Wuhan is located. As of 10 March 2023, the percentage had decreased to 0.047%. As of 10 March 2023, there were 676,609,955 total confirmed cases of SARS‑CoV‑2 infection. The total number of deaths attributed to the virus was 6,881,955.
== In cryptococcal meningitis == IRIS is particularly problematic in cryptococcal meningitis as IRIS is fairly common and can be fatal. IRIS has been described in immunocompetent hosts who have meningitis caused by Cryptococcus gattii and Cryptococcus neoformans var. grubii, environmental fungi which often affect immunocompetent hosts. Several weeks or even months into appropriate treatment, there is a sudden onset deterioration with worsening meningitis symptoms and progression or development of new neurological symptoms. Magnetic resonance imaging shows increase in the size of brain lesions, and CSF abnormalities (white cell count, protein, glucose) increase. CSF culture is typically sterile, and there is no increase in CSF cryptococcal antigen titer. The increasing inflammation can cause brain injury or be fatal. The general mechanism behind IRIS is increased inflammation as the recovering immune system recognizes the antigens of the fungus as immunosuppression is reversed. Cryptococcal IRIS has three phases:
Sources: en.wikipedia.org
Cetrimide, or alkyltrimethylammonium bromide, is an antiseptic which is a mixture of three quaternary ammonium compounds: tetradonium bromide (TTAB or MITMAB), cetrimonium bromide (CTAB), and laurtrimonium bromide (DTAB or LTAB). It was first discovered and developed by ICI and introduced under the brand name Cetavlon. It is used as a 1-3 % solution for cleaning roadside accident wounds. ICI also introduced Savlon, which was a combination of cetrimide and chlorhexidine. ICI sold the Savlon brand OTC to Johnson & Johnson in May 1992. Cetrimide is used in various applications such as antiseptic agents, diagnostic test and analysis, topical formulations, and dental treatment.
== History == In 1950, a small amount of CoQ10 was isolated from the lining of a horse's gut, a compound initially called substance SA, but later deemed to be quinone found in many animal tissues. In 1957, the same compound was isolated from mitochondrial membranes of beef heart, with research showing that it transported electrons within mitochondria. The compound was called Q-275 as a quinone. The Q-275/substance SA was later renamed ubiquinone as it was a ubiquitous quinone found in all animal tissues. In 1958, its full chemical structure was reported. Ubiquinone was later called either mitoquinone or coenzyme Q due to its participation to the mitochondrial electron transport chain. In 1966, a study reported that reduced CoQ6 was an effective antioxidant in cells.
== Early life == She was born in London to Georgian mother Nino Kvinitadze, daughter of General Giorgi Kvinitadze, and Anglo-Dutch father Peter Claude Holland d'Abo, of a landed gentry family of West Wratting, Cambridgeshire. Maryam d'Abo was raised in Paris and Geneva. D’Abo was drawing from the age of eight, but by 13 she wanted to become an actress; she joined an amateur theatre company while at school in Geneva. She decided to do a foundation course at the London College of Printing at 18, but she abandoned those studies in order to go to drama school at Drama Centre London. She left after one term in order to make her film debut.
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.
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.