If you have been reading about Pro-Gly-Pro 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 2025-11-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
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.
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.
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.
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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
=== Carbon dioxide reduction === A highly exothermic reaction combusts magnesium in an oxidation-reduction reaction with carbon dioxide, producing carbon nanoparticles including graphene and fullerenes.
==== Vitamins ==== Mashua contains substantial levels of vitamin C, as well as β-carotene, which can be converted into vitamin A. The levels of vitamin C in mashua are influenced by both the geographical area where it is grown and its genetic profile. A study conducted by Coloma et al. in 2022 found that the vitamin C levels in yellow mashua tubers range from 0.53 to 1.54 mg/g dry matter. The tubers that display both yellow and purple hues demonstrate a considerably higher vitamin C concentration, with a range of 0.9 to 3.36 mg/g dry matter. In comparison, potatoes, a more commonly known tuber, have a lower vitamin C content, with a range of 0.27 to 0.87 mg/g dry matter. This indicates that mashua can contain approximately two to four times more vitamin C than potatoes. Like vitamin C, the levels of β-carotene in tubers also fluctuate according to the cultivation location and the plant's genotype. For yellow tubers, β-carotene content ranges from 18.10 to 715.95 μg/g dry matter. The concentration spans from 6.91 to 336.33 μg/g dry matter in tubers with a yellow-purple hue. Conversely, purple tubers exhibit a β-carotene content significantly lower, varying from 1.21 to 4.46 μg/g dry matter.
1936: The first all-steel reefers entered service. 1946: Two experimental aluminum-body refrigerator cars entered service on the PFE; an experimental reefer with a stainless-steel body was built for the SFRD. 1950: The U.S. refrigerator car roster dropped to 127,200. 1957: The last ice bunker refrigerator cars were built. 1958: The first mechanical reefers (using diesel-powered refrigeration units) entered revenue service. 1959: The flush, "plug" style sliding door was introduced as an option, providing a larger door to ease loading and unloading. The tight-fitting doors were better insulated, helping the car maintain a more even temperature. An early example is the DT&I XL-1 car by Evans. 1966: Japanese National Railways started operation of fish freight express trains by newly built "resa 10000" type refers. 1969: ACF constructed several experimental center flow hopper cars incorporating mechanical cooling systems and insulated cargo cells. The units were intended for shipping bulk perishables. 1971: The last ice-cooled reefers were retired. 1980: The U.S. refrigerator car roster dropped to 80,000. 1986: The last reefers in Japan were replaced by reefer containers. 1990s: The first cryogenically cooled reefers entered service. 2001: The number of refrigerator cars in the United States bottomed out at approximately 8,000. 2005: The number of reefers in the United States climbs to approximately 25,000, due to significant new refrigerator car orders. 2006: Railex launches 55-car unit train reefer service between the U.S. West Coast and New York.
At low temperatures, the dominance of the T1.5 thermal conductivity contribution of the out-of-plane mode supersedes the T2 dependence of the linear modes. Some graphene phonon bands exhibit negative Grüneisen parameters, resulting in negative thermal expansion coefficient at low temperatures. The lowest negative Grüneisen parameters correspond to the lowest transverse acoustic ZA modes, whose frequencies increase with in-plane lattice parameter, akin to a stretched string with higher frequency vibrations.
Sources: en.wikipedia.org
== Synthesis and structure == 2-Aminoisobutyric acid can be prepared from acetone cyanohydrin, by reaction with ammonia followed by hydrolysis. The compound is not chiral, unlike most amino acids. It is a strong helix inducer in peptides due to Thorpe–Ingold effect of its gem-dimethyl group. Oligomers of Aib form 310 helices.
=== Role in cancer progression and therapy resistance === ITGA1 contributes to tumor progression by regulating survival, migration, invasion, and resistance to anticancer therapies. In Pancreatic Ductal Adenocarcinoma (PDAC), ITGA1-mediated collagen EMT signaling promotes the survival of mesenchymal tumor cell populations, metastatic dissemination, and resistance to gemcitabine treatment. Inhibition of ITGA1 increases sensitivity to chemotherapy, making treatment more effective and supporting its capacity as a potential therapeutic target. In glioma, ITGA1 contributes to temozolomide (TMZ) resistance by activating the PI3K/AKT/Bcl-2 signaling pathway. Increased ITGA1 activity promotes anti-apoptotic signaling which prevents tumor cells from apoptosizing therefore leading to survival of tumor cells. Suppressing ITGA1 increases apoptosis and improves TMZ sensitivity. ITGA1 expression in glioma is regulated by the hsa-miR01298-5p pathway, which directly binds the ITGA1 3' untranslated region to suppress ITGA1 expression. Increased ITGA1 reverses those effects, making resistance to chemotherapy more likely.
== Paregoric, U.S.P. formula == The principal active ingredient in paregoric is powdered opium. In the United States the formula for Paregoric U.S.P. is a tincture of opium 40 mL, anise oil 4 mL, benzoic acid 4 g, camphor 4 g, glycerin 40 mL, alcohol 450 mL, purified water 450 mL, diluted with alcohol to 1000 mL, and contains the equivalent of 0.4 mg/mL of anhydrous morphine; one ounce of paregoric contains 129.6 mg (2 grains) of powdered opium, or the equivalent of 13 mg of anhydrous morphine. The average adult dose is 4 mL by mouth which corresponds to 16 mg of opium, or 1.6 mg of anhydrous morphine. It is unclear when the current formula for Paregoric, U.S.P. was developed in the United States. One formula for "Camphorated Tincture of Opium (Paregoric Elixir)" attributed to the United States Pharmacoepia of 1863 is: "Macerate 1 drachm each powdered opium and benzoic acid, 1 fluid drachm of anise, 2 ounces clarified honey, and 2 scruples camphor, in 2 pints diluted alcohol for 7 days, and filter through paper." A slightly different formula is given in the 1926 pharmacoepia. The current formula for Paregoric, U.S.P. should not be assumed to be universal. For example, in the United Kingdom the formula for Paregoric, B.P. is tincture of opium 5 mL, benzoic acid 500 mg, camphor 300 mg, anise oil 0.3 mL, alcohol (60%) to 100 mL, and contains about 1/30th grain of anhydrous morphine in 60 minims, which is 25% stronger than Paregoric, U.S.P.
Sources: en.wikipedia.org
However, some in the Japanese archaeological community remain skeptical about the presence of cattle in Japan during the Yayoi period, and there is a persistent view that they were brought to Japan from the Korean peninsula by the toraijin, a group of people who came to Japan in the mid-5th century during the Kofun period. At the Nango-Ōhigashi site in Gose City, Nara Prefecture, excavations revealed cow bones believed to date back to the 5th century. At the Funamiya Kofun Tumulus (late 5th century) in Asago City, Hyōgo Prefecture, pieces of a cow-shaped haniwa (clay figurine), believed to be the oldest in Japan, have been excavated. In addition, a cow-shaped haniwa was excavated from the Hashida No. 1 Tumulus in Tawaramoto Town, Shiki-gun, Nara Prefecture in the first half of the 6th century, and was designated as an Important Cultural Property of Japan in 1958. On the other hand, recent genetic studies have shown that Wagyu and Korean cattle (Hanwoo and others) differ greatly in their genetic information. Livestock cattle are divided into two major lineages: northern lineage cattle (Bos taurus) and Indian lineage cattle (Bos indicus), and both Wagyu and Korean cattle belong to the northern lineage and do not contain Indian lineage such as Zebu cattle. However, in terms of mitochondrial DNA haplogroups, haplogroup T4 (East Asian type) is predominant in the Wagyu (Japanese Black) at about 65%, while haplogroup T3 (European type) is predominant in Korean cattle at 66–83%.
T cell development in the thymus. Video by Janice Yau, describing stromal signaling and tolerance. Department of Immunology and Biomedical Communications, University of Toronto. Master's Research Project, Master of Science in Biomedical Communications. 2011.
In Australia, diamorphine is listed as a schedule 9 prohibited substance under the Poisons Standard (October 2015). The state of Western Australia, in its Poisons Act 1964 (Reprint 6: amendments as at 10 September 2004), described a schedule 9 drug as: "Poisons that are drugs of abuse, the manufacture, possession, sale or use of which should be prohibited by law except for amounts which may be necessary for educational, experimental or research purposes conducted with the approval of the Governor."
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.