Everything below concerns freeze-thaw cycle. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
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.
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.
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.
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.
Many free and open-source software tools have existed and continued to grow since the 1980s. The combination of a continued need for new algorithms for the analysis of emerging types of biological readouts, the potential for innovative in silico experiments, and freely available open code bases have created opportunities for research groups to contribute to both bioinformatics regardless of funding. The open source tools often act as incubators of ideas, or community-supported plug-ins in commercial applications. They may also provide de facto standards and shared object models for assisting with the challenge of bioinformation integration. Open-source bioinformatics software includes Bioconductor, BioPerl, Biopython, BioJava, BioJS, BioRuby, Bioclipse, EMBOSS, .NET Bio, Orange with its bioinformatics add-on, Apache Taverna, UGENE and GenoCAD. The non-profit Open Bioinformatics Foundation and the annual Bioinformatics Open Source Conference promote open-source bioinformatics software.
The Le Havre Palace of Justice is located on the Boulevard de Strasbourg. With its annex, it includes a high court, a juvenile court, and a commercial court. The city also has a Labour Court and District Court. Among the legal services offered there are legal aid services and the application of penalties. Le Havre depends on the Court of Appeal of Rouen. The prison, which dates from the Second Empire, was completely destroyed in 2012. The new prison for Le Havre was completed in 2010 at Saint-Aubin-Routot east of the Le Havre agglomeration. It has an area of 32,000 m2 on a site of 15 hectares and can accommodate 690 people. The Hospital Group of Havre is a public health facility managed by a supervisory board chaired by the Mayor of Le Havre. Its main structures are Flaubert Hospital (the oldest, located downtown), the Monod Hospital (in Montivilliers), the Pierre Janet Hospital (psychiatry), the house for adolescents, day hospitals, and seniors' residences. It is the largest employer in the CODAH. Built in 1987, the Jacques Monod Hospital offers a full range of care in medicine, surgery, gynecology, obstetrics, pediatrics, geriatrics, mental health follow-up care, rehabilitation, reintegration, and public health. Finally, there are several private clinics that offer complete care: the private clinic of the Estuary groups together the old clinics of Petit Colmoulins and François I. The private clinic of Ormeaux is located in the neighbourhood of Eure.
One of the methods is sealing of covalent DNA bond, namely phosphodiester bond and nicks. Reconstruction of those structures performed with assistance of ligation. For instance, T4 DNA ligase serve as a catalyst for sealing of a nick between 3 prime and 5 prime ends of DNA to make up strong phosphodiester bond. Ligated structures have higher thermal stability values. T4 DNA ligase has many valuable properties such as already mentioned catalytic, but it is also responsible for sealing of the gaps between DNA strands, nick-closing activity, repair of the DNA damage, etc. In nanostructures architecture, molecular biology researches - ssDNA is an important application model. T4 DNA ligase used to cyclize short ssDNA fragments, but process is complicated by formation of secondary structures. On the other hand, Taq DNA ligase is a thermostable enzyme which can be applied at higher temperatures (45, 55 and 65 °C respectively). Since at these temperature range secondary structures less stable it is enhance cyclization efficiency of oligonucleotides. The kinetic, biological, and other parameters of nanostructures are influenced by presence of the secondary structures in DNA rings. However, Taq DNA ligation occur only when two complementary DNA strands are perfectly paired and have no gaps in between. Analysis of ligases activities, mutations, deficiencies widely used in drug design and biological researches to investigate diseases, pathologies developments and related rare acquired or inherited syndromes (e.g. DNA ligase IV syndrome).
As a result, the different nuclear spin states have different energies in a non-zero magnetic field. In less formal language, we can talk about the two spin states of a spin 1/2 as being aligned either with or against the magnetic field. If γ is positive (true for most isotopes used in NMR) then m = 1/2 ("spin up") is the lower energy state. The energy difference between the two states is:
The 1987 report of National Cholesterol Education Program, Adult Treatment Panels suggests the total blood cholesterol level should be: < 200 mg/dL normal blood cholesterol, 200–239 mg/dL borderline-high, > 240 mg/dL high cholesterol. The American Heart Association provides a similar set of guidelines for total (fasting) blood cholesterol levels and risk for heart disease: Statins are effective in lowering LDL cholesterol and widely used for primary prevention in people at high risk of cardiovascular disease, as well as in secondary prevention for those who have developed cardiovascular disease. The average global mean total cholesterol for humans has remained at about 4.6 mmol/L (178 mg/dL) for men and women, both crude and age standardized, for nearly 40 years from 1980 to 2018, with some regional variations and reduction of total cholesterol in Western nations. More current testing methods determine LDL ("bad") and HDL ("good") cholesterol separately, allowing cholesterol analysis to be more nuanced. The desirable LDL level is considered to be less than 100 mg/dL (2.6 mmol/L).
Sources: en.wikipedia.org
===== Water-soluble vitamins ===== Cats can synthesize niacin, but its breakdown exceeds the rate at which it can be synthesized, so they have a higher requirement for it, which can be fulfilled through an animal-based diet. Pyridoxine (vitamin B6) is required in increased amounts because it is essential for amino acid metabolism. Vitamin B12 is an AAFCO-recommended vitamin that is essential for the metabolism of carbohydrates and protein, supports the nervous system and mucous membranes, contributes to muscle and heart function, and promotes normal growth and development. Choline is also an AAFCO-recommended ingredient for kittens; it is important for neurotransmission in the brain and serves as a component of membrane phospholipids. Biotin (vitamin B7) is another AAFCO-recommended vitamin that supports the thyroid and adrenal glands as well as the reproductive and nervous systems. Kittens also require riboflavin (vitamin B2) for heart health, pantothenic acid (vitamin B5), and folacin (vitamin B9).
Exhausted, I then slept, to awake next morning refreshed, with a clear head, though still somewhat tired physically. A sensation of well-being and renewed life flowed through me. Breakfast tasted delicious and gave me extraordinary pleasure. When I later walked out into the garden, in which the sun shone now after a spring rain, everything glistened and sparkled in a fresh light. The world was as if newly created. All my senses vibrated in a condition of highest sensitivity, which persisted for the entire day. During a speech on his 100th birthday in 2006, Hofmann additionally said of LSD:
Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into interstitial spaces where they are absorbed into blood rather than through a duct. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs. The hypothalamus and the anterior pituitary are two out of the three endocrine glands that are important in cell signaling. They are both part of the HPA axis which is known to play a role in cell signaling in the nervous system. The hypothalamus is a key regulator of the autonomic nervous system. The endocrine system has three sets of endocrine outputs which include the magnocellular system, the parvocellular system, and autonomic intervention. The magnocellular is involved in the expression of oxytocin or vasopressin. The main role of the anterior pituitary gland is to produce and secrete tropic hormones. Some examples of tropic hormones secreted by the anterior pituitary gland include TSH, ACTH, GH, LH, and FSH. The parvocellular neurosecretory cell is involved in controlling the secretion of hormones from the anterior pituitary.
=== Drug manufacturing === Due to the environmental factors present in outer space, alternative manufacturing methods are explored to produce medicines for astronaut use. For example, measuring the weight and volume of medicine ingredients in microgravity conditions is difficult and requires zero-gravity mass measurement devices. Current manufacturing methods also rely heavily on large and heavy machining, which cannot fit on spacecraft due to constrained spaces. New manufacturing methods for medicines have been developed that can adapt to outer space's environmental constraints. Chemputing is a chemical-robot system that uses limited technology to synthesize raw materials for pharmaceuticals. This apparatus includes a reaction flask, a jacketed filtration setup, an automated liquid-liquid separation module, and a solvent evaporation module, allowing astronauts to develop compounds on demand, not requiring a large space and taking into account the constraints of spaceflight. Additive manufacturing has already been used on Earth in the personalized medicine field and there are methods sent to outer space for drug manufacturing and fabrication.
=== Anti-mitotic agent === Moroidin has shown to have anti-mitotic properties, chiefly by inhibiting the polymerization of tubulin. Tubulin protein polymers are the major component of microtubules. During mitosis, microtubules form the organizing structure called the mitotic apparatus, which captures, aligns, and separates chromosomes. The proper alignment and separation of chromosomes is critical to ensure that cells divide their genetic material equally between daughter cells. Failure to attach chromosomes to the mitotic apparatus activates the mitotic checkpoint, preventing cells from entering anaphase to proceed with cell division. Agents that disrupt microtubules therefore inhibit mitosis through activation of this checkpoint. Moroidin and its related compounds, the celogentins, inhibit tubulin polymerization. Of this family, celogentin C is the most potent (IC50 0.8×10−6 M), and it is more potent than the anti-mitotic agent vinblastine (IC50 3.0×10−6). Moroidin has the same potency as vinblastine. Because of this biological activity, compounds in this family have potential as anti-cancer agents. The mechanism of tubulin disruption is not known, but the degree of biological activity has been linked to the structure of the right-hand ring containing the Trp-His linkage. Moroidin and the celogentins can be divided into three groups according to structural similarity of the right-hand ring. Celogentin C, the most potent compound, has a unique right-hand ring containing a proline residue.
Sources: en.wikipedia.org
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.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.