lyophilization 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 2026-04-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
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.
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.
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.
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.
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.
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.
Linear azole(in)e-containing peptides (LAPs) contain thiazoles and oxazoles, or their reduced thiazoline and oxazoline forms. Thiazol(in)es are the result of cyclization of Cys residues in the precursor peptide, while (methyl)oxazol(in)es are formed from Thr and Ser. Azole and azoline formation also modifies the residue in the -1 position, or directly C-terminal to the Cys, Ser, or Thr. A dehydrogenase in the LAP gene cluster is required for oxidation of azolines to azoles. Plantazolicin is a LAP with extensive cyclization. Two sets of five heterocycles endow the natural product with structural rigidity and unusually selective antibacterial activity. Streptolysin S (SLS) is perhaps the most well-studied and most famous LAP, in part because the structure is still unknown since the discovery of SLS in 1901. Thus, while the biosynthetic gene cluster suggests SLS is a LAP, structural confirmation is lacking.
== Safety profile == Apart from procedural pain, some common post-treatment adverse events (AEs) of MNs include temporary discomfort, erythema (skin redness), and edema. Pinpoint bleeding, itching, irritation, and bruising are also possible in some cases. However, most of the adverse side effects are not long-lasting and could be resolved spontaneously within 24 hours after the treatment, making MNs a rather safe tool. Photoprotection and minimal exposure to chemicals irritants are often advised for an effective recovery and lowered chance of skin inflammation. Severe risks may be possible if there are technical errors during the procedure. For example, the usage of non-sterile tools might result in post-inflammatory hyperpigmentation, systemic hypersensitivity, local infections, etc. Moreover, if excess pressure is used over a bony prominence, it could lead to "Tram-track scarring". But this could be avoided by using smaller needles and prevent over-pressurizing on top of these areas. In addition, if the patient is allergic to the either the drug used or the material of MNs, contact dermatitis is possible. Therefore, clinicians should be cautious towards patients with high risks of allergy.
== External links == How wounds heal and tumors form With this simple Flash demonstration, Harvard professor Donald Ingber explains how wounds heal, why scars form, and how tumors develop. Presented by Children's Hospital Boston. Wound Healing and Repair Lorenz H.P. and Longaker M.T. Wounds: Biology, Pathology, and Management. Stanford University Medical Center. Romo T. and McLaughlin L.A. 2003. Wound Healing, Skin. Emedicine.com. Rosenberg L. and de la Torre J. 2003. Wound Healing, Growth Factors. Emedicine.com. After the Injury- Children's Hospital Of Philadelphia
=== Modern uses === Today, animal glues are sparsely industrialized, but still used for making and restoring violin family instruments, paintings, illuminated parchment manuscripts, and other artifacts. Gelatin, a form of animal glue, is found in many contemporary products, such as gelatin desserts, marshmallows, pharmaceutical capsules, and photographic film, and is used to reinforce sinew wrappings, wood, leather, bark and paper. Hide glue is also preferred by many luthiers over synthetic glues for its reversibility, creep-resistance and tendency to pull joints closed as it cures. As well as being used as an adhesive, animal glue is used for sizing or varnish, although it is not as frequently used as other adhesives because it is water-soluble. Other aspects, such as the difficulty of storing it in a wet state and the need for fresh raw materials (the animal skin cannot be rotten or grease-burned), make it more difficult to obtain and use. Factories now produce other forms of adhesives, as the process for animal glue is complex. Animal glues will also darken with age and shrink as they dry, giving them the potential to harm wood, paper, or works of art. Too much handling and too many changes in temperature or humidity can cause further harm. Some companies in Canada and other countries still produce animal, hide and hoof glues from horses. Recently, animal glue has been replaced by other adhesives and plastics, but remains popular for restoration.
While the method of chemical characterization of a daughter was successful for flerovium and livermorium, and the simpler structure of even–even nuclei made confirmation of oganesson (Z = 118) straightforward, there have been difficulties in establishing the congruence of decay chains from isotopes with odd protons, odd neutrons, or both. To get around this problem with hot fusion, the decay chains from which terminate in spontaneous fission instead of connecting to known nuclei as cold fusion allows, experiments were done in Dubna in 2015 to produce lighter isotopes of flerovium by reaction of 48Ca with 239Pu and 240Pu, particularly 283Fl, 284Fl, and 285Fl; the last had previously been characterized in the 242Pu(48Ca,5n)285Fl reaction at Lawrence Berkeley National Laboratory in 2010. 285Fl was more clearly characterized, while the new isotope 284Fl was found to undergo immediate spontaneous fission, and 283Fl was not observed. This lightest isotope may yet conceivably be produced in the cold fusion reaction 208Pb(76Ge,n)283Fl, which the team at RIKEN in Japan at one point considered investigating: this reaction is expected to have a higher cross-section of 200 fb than the "world record" low of 30 fb for 209Bi(70Zn,n)278Nh, the reaction which RIKEN used for the official discovery of element 113 (nihonium). Alternatively, it might be produced in future as a great-granddaughter of 295120, reachable in the 249Cf(50Ti,4n) reaction.
Sources: en.wikipedia.org
Benfluorex, sold under the brand name Mediator, is an anorectic and hypolipidemic agent that is structurally related to fenfluramine (a substituted amphetamine). It acts mostly as a prodrug of norfenfluramine. It was fraudulently claimed to improve glycemic control and decrease insulin resistance in people with poorly controlled type-2 diabetes through norfenfluramine acting as a 5-HT2B receptor agonist It was on the market between 1976 and 2009, and is thought to have caused between 500 and 2,000 deaths. It was patented and manufactured by the French pharmaceutical company Servier. However, Servier has wittingly concealed the nature of Benfluorex, so that it would avoid the ban of Fenfluramine-related medications, which were mostly marketed by Servier (Racemic Fenfluramine/Ponderal, Dexfenfluramine/Isomeride) Servier has been found to be aware of the Fenfluramine-structure nature when starting marketing Benfluorex as an anti diabetic. The mechanism of action of Benfluorex was the anoretic property that is shared with the other Fenfluramine-related compounds. In fact, Benfluorex acts as a prodrug to norfenfluramine, a worldwide withdrawn anorectic because of its high incidence of cardiac fibrosis which is completely out of line for treating type 2 diabetes.
According to a February 2015 Newsweek report, Houthis are fighting "for things that all Yemenis crave: government accountability, the end to corruption, regular utilities, fair fuel prices, job opportunities for ordinary Yemenis and the end of Western influence". In forming alliances, the Houthi movement has been at times opportunistic, partnering with countries it later declared as enemies, including the United States. The influx of various individual and tribal interests has somewhat diluted the movement's original vision over time. Around the time of the third Saada war (November 2005–February 2006), the conflict was increasingly waged "along the lines of prevalent tribal feuds", which distorted the initial socio-economic, religious and ideological aims of Hussein al-Houthi.
== Uses == Like G. lucidum, G. tsugae is non-poisonous but generally considered inedible, because of its solid woody nature; however, teas and extracts made from its fruiting bodies supposedly allow medicinal use of the compounds it contains, although this is controversial within the scientific community. A hot water extraction or tea can be very effective for extracting the polysaccharides; however, an alcohol or alcohol/glycerin extraction method is more effective for the triterpenoids. The fresh, soft growth of the "lip" of G. tsugae can be sautéed and prepared much like other edible mushrooms. While in this nascent stage it is not woody, it can still be tough and chewy.
=== German reunification === West German chancellor Helmut Kohl's proposal of a Ten Point Plan on 28 November 1989—a graduated progression from confederation to full federation—moved the German question from a mere platitude to actual politics almost overnight, and the storm of international criticism it provoked was the price of that shift. Gorbachev's opposition, Thatcher's criticism, and French president François Mitterrand's vacillation notwithstanding, Kohl pushed for immediate unification once Dresden crowds took up chanting his name that December; unlike their more cautious political elites, ordinary people in the neighboring countries mostly favored German self-determination. This proposal presented a special dilemma for Gorbachev, since a "divided Germany" had been central to Soviet security strategy since the Stalin era. The resulting Two-Plus-Four negotiations—originally conceived by the U.S. State Department as a "four-plus-two" framework joining the wartime Allies with the two German states, then inverted to acknowledge German sensitivities—translated the East German electorate's March 1990 mandate into an accepted international settlement. In return, Kohl accepted the Oder–Neisse line as Germany's permanent eastern frontier in exchange for keeping reparations off the table, while American pressure and West German aid persuaded Gorbachev to permit a reunified Germany to remain in NATO. Then U.S. Secretary of State James Baker assured Gorbachev on 9 February 1990 that NATO would not expand eastward.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.