Everything below concerns Lyophilisation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
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.
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.
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.
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.
== Coups d'état == "...Thailand has experienced more coups d'état than any other country in contemporary history." according to The Washington Post. Since 1932, Thailand has had seven coup attempts and 12 successful coups (as of 2015).
==== Training and qualification ==== In Europe, the training of physicians in Clinical/Medical Genetics is overseen by the Union Européenne des Médecins Spécialistes (UEMS). This organization aims to harmonize and raise the standards of medical specialist training across Europe. The UEMS has established European Training Requirements (ETR) for Medical Genetics to guide the education and training of medical geneticists. Individuals seeking acceptance into clinical genetics training programs must hold an MD, or in some countries, an MB ChB or MB BS degree. These qualifications ensure that trainees have the foundational medical knowledge required to specialize in Medical Genetics. The optimal training program involves a total of five years: one year of general medical training (the "common trunk", often covering fields such as general practice, pediatrics, obstetrics and gynecology, neurology, psychiatry, and internal medicine) followed by four years of specialized training in Medical Genetics. This specialized training should include at least two years of clinical patient care and at least six months in genetic laboratory diagnostics. Trainees' progress is evaluated through a structured program that begins with observation and progresses to independent practice under supervision, culminating in the ability to manage complex cases independently. Final certification involves a comprehensive assessment, which may include national examinations or the European Certificate in Medical Genetics and Genomics (ECMGG).
== Applications == CyTOF provides important information at a single cell level about protein expression, immunophenotype, and functional characterization. It is a valuable tool in immunology, where the large number of parameters has helped to elucidate the workings of this complex system. For example, natural killer cells have diverse properties affected by numerous markers in various combinations, which could not be analyzed with ease prior to this technology. Simultaneously measuring many biomarkers makes it possible to identify over 30 distinct immunophenotype subsets within one complex group of cells. This can help to more fully characterize immune function, infectious disease, and cancers, and understand cells response to therapy.
On 24 February 2022, Russia launched a full-scale invasion of Ukraine, occupying large parts of the country and unilaterally declaring the annexation of southeastern Ukraine in September that year. Soon after, journalist H. D. S. Greenway cited the Russian invasion of Ukraine and 4 February joint statement between Russia and China (under Putin and Xi Jinping) as one of the signs that Cold War II had officially begun. Jaro Bilocerkowycz, Associate Professor of Political Science at the University of Dayton, wrote that the invasion of Ukraine could be the start of a "new Cold War", placing Ukraine "at the center of a geopolitical struggle reminiscent of the Cold War days when Germany and its capital city Berlin were split in two". In March 2022, Harvard historian Fredrik Logevall asserted that the conflict over Ukraine was "fundamentally different from the Cold War" because it did not have the "massive arms race and a general absence of diplomacy, and a deep ideological schism". Yale historian Arne Westad agreed and said that Putin's statements about Ukraine resembled late 19th- and early 20th-century colonial and imperial ideas, rather than those of the Cold War. In June 2022, journalist Gideon Rachman asserted the Russian invasion of Ukraine as the start of a second Cold War. In response to US plans to deploy long-range missiles in Germany, including SM-6 and Tomahawk cruise missiles and developmental hypersonic weapons, Putin stated in July 2024 that the situation was reminiscent of the Cold War.
Sources: en.wikipedia.org
== Carbohydrate control in invertebrates == Insects have two types of "blood sugar", the monosaccharide glucose and the disaccharide trehalose. Trehalose is the major carbohydrate used by insects for flight. The concentrations of the carbohydrates trehalose and glucose in the insect hemolymph are tightly controlled by multiple enzymes and hormones, including trehalase, insulin-like peptides (ILPs and DILPs), adipokinetic hormone (AKH), leucokinin (LK), octopamine and other mediators, thereby maintaining carbohydrate homeostasis by endocrine and metabolic feedback mechanisms.
A total synthesis of progesterone was reported in 1971 by William S. Johnson. The synthesis begins with reacting the phosphonium salt 7 with phenyl lithium to produce the phosphonium ylide 8. The ylide 8 is reacted with an aldehyde to produce the alkene 9. The ketal protecting groups of 9 are hydrolyzed to produce the diketone 10, which in turn is cyclized to form the cyclopentenone 11. The ketone of 11 is reacted with methyl lithium to yield the tertiary alcohol 12, which in turn is treated with acid to produce the tertiary cation 13. The key step of the synthesis is the π-cation cyclization of 13 in which the B-, C-, and D-rings of the steroid are simultaneously formed to produce 14. This step resembles the cationic cyclization reaction used in the biosynthesis of steroids and hence is referred to as biomimetic. In the next step the enol orthoester is hydrolyzed to produce the ketone 15. The cyclopentene A-ring is then opened by oxidizing with ozone to produce 16. Finally, the diketone 17 undergoes an intramolecular aldol condensation by treating with aqueous potassium hydroxide to produce progesterone.
A thermal shift assay (TSA) measures the stability of a protein by the change in its thermal denaturation temperature. This is done under varying conditions, such as variations in drug concentration, buffer formulation (pH or ionic strength), redox potential, or sequence mutation. The most common method for measuring protein thermal shifts is differential scanning fluorimetry (DSF). DSF methodology includes techniques such as nanoDSF, which relies on the intrinsic fluorescence from native tryptophan or tyrosine residues, and Thermofluor, which utilizes extrinsic fluorogenic dyes. The binding of low molecular weight ligands can increase the thermal stability of a protein, as described by Daniel Koshland (1958) and Kaj Ulrik Linderstrøm-Lang and Schellman (1959). Almost half of enzymes require a metal ion co-factor. Thermostable proteins are often more useful than their non-thermostable counterparts, e.g., DNA polymerase in the polymerase chain reaction, so protein engineering often includes adding mutations to increase thermal stability. Protein crystallization is more successful for proteins with a higher melting point and adding buffer components that stabilize proteins improve the likelihood of protein crystals forming. If examining pH then the possible effects of the buffer molecule on thermal stability should be taken into account along with the fact that pKa of each buffer molecule changes uniquely with temperature. Additionally, any time a charged species is examined the effects of the counterion should be accounted for.
=== Wound healing and tissue repair === Even though PDRN's positive effects on wound healing and tissue repair were initially observed only in ephithelial tissue, it has also shown these effects across multiple tissue models. For instance, studies focused in wound closure in diabetic foot ulcers showed that PDRN can significantly reduce the time compared to placebo. The use of PDRN for wound treatment in clinical trials is considered cost-effective since it reduces hospital stays and the need for additional treatments. Moreover, PDRN showed significant improvement of mucosal healing, reduction of tissue injury and promotion of restoration of intestinal structure and function in a murine colitis model. However, one of the most common applications of this molecule in Asia is as a dematological biostumulator, because of its positive effects on the skin after abrasive procedures like laser or microneedling.
Fidelity of feedback responses between diverse cell types and the immune system depends on the integrity of mechanisms that limit the range of genes activated by NF-κB, allowing only expression of genes which contribute to an effective immune response and subsequently, a complete restoration of tissue function after resolution of inflammation. In cancer, mechanisms that regulate gene expression in response to inflammatory stimuli are altered to the point that a cell ceases to link its survival with the mechanisms that coordinate its phenotype and its function with the rest of the tissue. This is often evident in severely compromised regulation of NF-κB activity, which allows cancer cells to express abnormal cohorts of NF-κB target genes. This results in not only the cancer cells functioning abnormally: cells of surrounding tissue alter their function and cease to support the organism exclusively. Additionally, several types of cells in the microenvironment of cancer may change their phenotypes to support cancer growth. Inflammation, therefore, is a process that tests the fidelity of tissue components because the process that leads to tissue regeneration requires coordination of gene expression between diverse cell types.
Sources: en.wikipedia.org
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.