lyophilized powder raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-10-29. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
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.
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.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
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.
Several efforts to develop standards in the NGS field have been attempted to address these challenges, most of which have been small-scale efforts arising from individual labs. Most recently, a large, organized, FDA-funded effort has culminated in the BioCompute standard. On 26 October 1990, Roger Tsien, Pepi Ross, Margaret Fahnestock and Allan J Johnston filed a patent describing stepwise ("base-by-base") sequencing with removable 3' blockers on DNA arrays (blots and single DNA molecules). In 1996, Pål Nyrén and his student Mostafa Ronaghi at the Royal Institute of Technology in Stockholm published their method of pyrosequencing. On 1 April 1997, Pascal Mayer and Laurent Farinelli submitted patents describing DNA colony sequencing. The DNA sample preparation and random surface-polymerase chain reaction (PCR) arraying methods described in this patent, coupled to Roger Tsien et al.'s "base-by-base" sequencing method, is now implemented in Illumina's Hi-Seq genome sequencers. In 1998, Phil Green and Brent Ewing of the University of Washington described their phred quality score for sequencer data analysis, a landmark analysis technique that gained widespread adoption, and which is still the most common metric for assessing the accuracy of a sequencing platform. Lynx Therapeutics published and marketed massively parallel signature sequencing (MPSS), in 2000.
=== Amino acid synthesis === Six essential amino acids and three nonessential are synthesized from oxaloacetate and pyruvate. Aspartate and alanine are formed from oxaloacetate and pyruvate, respectively, by transamination from glutamate. Asparagine is synthesized by amidation of aspartate, with glutamine donating the NH4. These are nonessential amino acids, and their simple biosynthetic pathways occur in all organisms. Methionine, threonine, lysine, isoleucine, valine, and leucine are essential amino acids in humans and most vertebrates, meaning that oxaloacetate cannot be converted into any of these aminos. However they can be synthesizers in bacteria via biosynthetic pathways that are complex and interconnected.
== Description == Bryant Park is located between Fifth and Sixth Avenues and between 40th and 42nd Streets, and covers 9.6 acres (3.9 ha). Although technically the main branch of the New York Public Library is located within the park, in design it forms the eastern boundary of the park's green space, making Sixth Avenue the park's primary entrance. Bryant Park is used mostly as a passive recreation space, and lacks active sports facilities. Bryant Park is several steps above the surrounding streets, enclosed by a retaining wall. Granite stairs at several locations provide access from the surrounding sidewalks. The surrounding area contains numerous structures, including the Bank of America Tower and 1095 Avenue of the Americas to the northwest; the Bryant Park Studios, American Radiator Building, Engineers' Club Building, and 452 Fifth Avenue to the south; 461 Fifth Avenue and the Stavros Niarchos Foundation Library to the southeast; and 500 Fifth Avenue, the Aeolian Building, and the W.R. Grace Building to the north. One of the park's largest features is a large lawn located slightly below the level of the surrounding walkways. Besides serving as a "lunchroom" for office workers, the lawn serves as the seating area for some of the park's major events, such as Bryant Park Movie Nights, Broadway in Bryant Park, and Square Dance. The lawn's season runs from February until October, when it is closed to make way for Bank of America Winter Village. Numerous walkways surround the central lawn. The northern and southern sides are each flanked by two flagstone walkways.
Sources: en.wikipedia.org
Unprovoked venous thrombosis may be related to inherited thrombophilias (e.g., factor V Leiden, antithrombin deficiency, and various other genetic deficiencies or variants), particularly in younger patients with family history of thrombosis; however, thrombotic events are more likely when acquired risk factors are superimposed on the inherited state.
== Etymology == The name "Colombia" is derived from the last name of the Italian navigator Christopher Columbus (Latin: Christophorus Columbus, Italian: Cristoforo Colombo, Spanish: Cristóbal Colón). It was conceived as a reference to all of the New World. The name was later adopted by the Republic of Colombia of 1819, formed from the territories of the old Viceroyalty of New Granada (modern-day Colombia, Panama, Venezuela, Ecuador, and northwest Brazil). When Venezuela, Ecuador, and Cundinamarca came to exist as independent states, the former Department of Cundinamarca adopted the name "Republic of New Granada". New Granada officially changed its name in 1858 to the Granadine Confederation. In 1863 the name was again changed, this time to United States of Colombia, before finally adopting its present name – the Republic of Colombia – in 1886. To refer to this country, the Colombian government uses the terms Colombia and República de Colombia.
DHA (dihydroxyacetone, also known as glycerone) is not a dye, stain or paint, but causes a chemical reaction with the amino acids in the dead layer on the skin surface. One of the pathways is a free radical-mediated Maillard reaction. The other pathway is the conventional Maillard reaction, a process well known to food chemists that causes the browning that occurs during food manufacturing and storage. It does not involve the underlying skin pigmentation nor does it require exposure to ultraviolet light to initiate the color change. However, for the 24 hours after self-tanner is applied, the skin is especially susceptible to ultraviolet, according to a 2007 study led by Katinka Jung of the Gematria Test Lab in Berlin. Forty minutes after the researchers treated skin samples with high levels of DHA they found that more than 180 percent additional free radicals formed during sun exposure compared with untreated skin. Another self-tanner ingredient, erythrulose, produced a similar response at high levels. For a day after self-tanner application, excessive sun exposure should be avoided and sunscreen should be worn outdoors, they say; an antioxidant cream could also minimize free radical production. Although some self-tanners contain sunscreen, its effect will not last long after application, and a fake tan itself will not protect the skin from UV exposure. The study by Jung et al. further confirms earlier results demonstrating that dihydroxyacetone in combination with dimethylisosorbide enhances the process of (sun-based) tanning.
Province of German Bohemia (Provinz Deutschböhmen), the regions of northern and western Bohemia; proclaimed a constitutive state (Land) of the German-Austrian Republic with Reichenberg (Liberec) as capital, administered by a Landeshauptmann (state captain), consecutively: Rafael Pacher (1857–1936), 29 October – 6 November 1918, and Rudolf Ritter von Lodgman von Auen (1877–1962), 6 November – 16 December 1918 (the last principal city was conquered by the Czech army but he continued in exile, first at Zittau in Saxony and then in Vienna, until 24 September 1919). Province of the Sudetenland (Provinz Sudetenland), the regions of northern Moravia and Austrian Silesia; proclaimed a constituent state of the German-Austrian Republic with Troppau (Opava) as capital, governed by a Landeshauptmann: Robert Freissler (1877–1950), 30 October – 18 December 1918. This province's boundaries do not correspond to what would later be called the Sudetenland, which contained all the German-speaking parts of the Czech lands. Bohemian Forest Region (Böhmerwaldgau), the region of Bohemian Forest/South Bohemia; proclaimed a district (Kreis) of the existing Austrian Land of Upper Austria; administered by Kreishauptmann (district captain): Friedrich Wichtl (1872–1922) from 30 October 1918. German South Moravia (Deutschsüdmähren), proclaimed a District (Kreis) of the existing Austrian land Lower Austria, administered by a Kreishauptmann: Oskar Teufel (1880–1946) from 30 October 1918. The U.S.
Sources: en.wikipedia.org
== Function == In a biological context, ROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. In plants, ROS are involved in metabolic processes related to photoprotection and tolerance to various types of stress. However, ROS can cause irreversible damage to DNA as they oxidize and modify some cellular components and prevent them from performing their original functions. This suggests that ROS has a dual role; whether they will act as harmful, protective or signaling factors depends on the balance between ROS production and disposal at the right time and place. In other words, oxygen toxicity can arise both from uncontrolled production and from the inefficient elimination of ROS by the antioxidant system. ROS are intermediates in the redox behavior of O2, which is central to fuel cells. During times of environmental stress (e.g., UV or heat exposure), ROS levels can increase dramatically. This may result in significant damage to cell structures. Cumulatively, this is known as oxidative stress. The production of ROS is strongly influenced by stress factor responses in plants, these factors that increase ROS production include drought, salinity, chilling, defense of pathogens, nutrient deficiency, metal toxicity and UV-B radiation. ROS are also generated by exogenous sources such as ionizing radiation generating irreversible effects in the development of tissues in both animals and plants.
Cocaine can induce tolerance after a single dose, and repeated use frequently leads to the development of addiction and prolonged craving. Assessment tools like the Obsessive Compulsive Cocaine Use Scale (OCCUS) may be employed to quantify obsessive and compulsive thoughts related to cocaine consumption. Withdrawal symptoms include disrupted sleep, irritability, depression, and reduced ability to experience pleasure (anhedonia). Chronic nasal use may cause destructive damage to the nasal septum, including cocaine-induced midline destructive lesions (CIMDL). Illicit cocaine is frequently adulterated with substances such as fentanyl, levamisole, or local anesthetics, increasing its toxicity. Concurrent use with alcohol produces cocaethylene, a metabolite that significantly increases the risk of sudden death. According to the Global Burden of Disease Study, cocaine use is responsible for approximately 7,300 deaths annually. Cocaine abuse can trigger addiction-related structural neuroplasticity in the human brain, although the permanence of such changes remains uncertain. Family history is a known risk factor, as relatives of cocaine users have an increased likelihood of developing cocaine addiction. A key mechanism involves the overexpression of ΔFosB in the nucleus accumbens, altering transcriptional regulation and reinforcing drug-seeking behavior. Each dose of cocaine raises ΔFosB levels without a known saturation point.
In another example, the stable radical TEMPO was attached to the graphene-coated cobalt nanoparticles via a diazonium reaction. The resulting catalyst was then used for the chemoselective oxidation of primary and secondary alcohols.
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.