This is a working overview of Reversed-phase HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-26 and is reviewed periodically as new material appears.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
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.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
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.
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.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
However, this occurs mostly in prostate cancer patients who take very high doses of cyproterone acetate; liver toxicity has not been reported in transgender women. Cyproterone acetate also has a variety of other adverse effects, such as fatigue and weight gain, and risks, such as blood clots and benign brain tumors, among others. High dosages of cyproterone-based medication have been linked with meningioma. Periodic monitoring of liver enzymes and prolactin levels may be advisable during cyproterone acetate therapy. Medroxyprogesterone acetate is a progestin that is related to cyproterone acetate and is sometimes used as an alternative to it. It is specifically used as an alternative to cyproterone acetate in the United States, where cyproterone acetate is not approved for medical use and is unavailable. Medroxyprogesterone acetate suppresses testosterone levels in transgender women similarly to cyproterone acetate. Oral medroxyprogesterone acetate has been found to suppress testosterone levels in men by about 30 to 75% across a dosage range of 20 to 100 mg/day. In contrast to cyproterone acetate however, medroxyprogesterone acetate is not also an androgen receptor antagonist. Medroxyprogesterone acetate has similar side effects and risks as cyproterone acetate, but is not associated with liver problems. Numerous other progestogens and by extension antigonadotropins have been used to suppress testosterone levels in men and are likely useful for such purposes in transgender women as well.
=== Procedures === There are five major Microtox tests including the Basic Test, the 100% Test, the Solid Phase Test, the Comparison Test, and the Inhibition Test. Of these five tests, three are used for sediment and soil testing including the Basic Test, the 100% Test and the Solid-Phase Test. All of these versions follow the same general method of reconstituting the Allivibrio fischeri reagent in the Reconstitution Solution. Corrections are made for salinity and particulate matter, then the bacteria are exposed to the sample solution depending on the methods of the particular test. The light output of the bacteria is measured using a photometer after five and 15 minutes from exposing the bacteria to the samples. The light measured directly correlates to the toxicity of the sample, producing data that allows for the calculation of EC50 or IC50s, or other ECxx and ICxx values. Acute Toxicity Basic Test is a procedure that measures the relative acute toxicity of a sample. This test is the best protocol for testing samples of unknown toxicity, a high level of toxicity, or when the test results are required to provide the highest confidence and precision. This test consists of two controls and eight sample dilutions in duplicate. Acute Toxicity 100% Test is a procedure that tests the sample at 100% sample concentration and as a result includes adding reagent solution directly to the sample. This test is used for samples that are expected to have a low level of toxicity and is generally used as an environmental screening tool.
=== Twenty-first century === In the twenty-first century, the aim has been to develop more permanent beak trimming (although repeat trimming may be required), using electrically heated blades in a beak trimming machine, to provide a self-cauterizing cut. By 2012 there were four widely used methods of beak trimming: hot blade, cold blade (including scissors or secateurs), electrical (the Bio-beaker) and infrared. The latter two methods usually remove only the tip of the beak and do not leave an open wound; therefore they may offer improvements in welfare. Other approaches such as the use of lasers, freeze drying and chemical retardation have been investigated but are not in widespread use. The infrared method directs a strong source of heat into the inner tissue of the beak and after a few weeks, the tip of the upper and lower beak dies and drops off making the beak shorter with blunt tips. The Bio-beaker, which uses an electric current to burn a small hole in the upper beak, is the preferred method for trimming the beaks of turkeys. The Farm Animal Welfare Council (FAWC) wrote regarding beak trimming of turkeys that cold cutting was the most accurate method, but that substantial re-growth of the beak occurred; although the Bio-beaker limited beak re-growth, it was less accurate. It was considered that the hot cut was the most distressing procedure for turkeys. In the UK, beak trimming of layer hens normally occurs at 1-day of age at the same time as the chick is being sexed and vaccinated.
Sources: en.wikipedia.org
In humans, replication protein A is the best-understood member of this family and is used in processes where the double helix is separated, including DNA replication, recombination, and DNA repair. These binding proteins seem to stabilize single-stranded DNA and protect it from forming stem-loops or being degraded by nucleases.
Insect-resistant crops have proven to lower pesticide usage, therefore reducing the environmental impact of pesticides as a whole. However, opponents have objected to GM crops per se on several grounds, including environmental concerns, whether food produced from GM crops is safe, whether GM crops are needed to address the world's food needs, and economic concerns raised by the fact these organisms are subject to intellectual property law. Biotechnology has several applications in the realm of food security. Crops like Golden rice are engineered to have higher nutritional content, and there is potential for food products with longer shelf lives. Though not a form of agricultural biotechnology, vaccines can help prevent diseases found in animal agriculture. Additionally, agricultural biotechnology can expedite breeding processes in order to yield faster results and provide greater quantities of food. Transgenic biofortification in cereals has been considered as a promising method to combat malnutrition in India and other countries.
== Discovery == Asprosin was first identified by Dr. Atul Chopra and colleagues at Baylor College of Medicine during their study of Marfanoid–progeroid–lipodystrophy syndrome (MPL), also known as neonatal progeroid syndrome (NPS), a rare genetic disorder caused by mutations in the FBN1 gene. These mutations produce truncated profibrillin-1 protein, resulting in two key effects: the production of a mutant fibrillin-1 protein and significantly reduced plasma asprosin levels due to a dominant-negative mechanism. The discovery of asprosin's role as a fasting-induced glucogenic hormone, stimulating hepatic glucose release, stemmed from the observation of low plasma insulin levels in the two patients. A subsequent study by Chopra and colleagues investigated the patients' extreme thinness and abnormally low appetite, uncovering asprosin's additional role as an orexigenic hormone that regulates appetite through hypothalamic neurons. To further investigate the condition, Chopra and colleagues developed a mouse model carrying the MPL mutation, which faithfully phenocopied the human disorder. These mice exhibited the same features as the patients, including low plasma asprosin levels, extreme thinness, reduced appetite, and resistance to diet-induced obesity and diabetes. This model confirmed the role of asprosin in regulating appetite and body weight through its orexigenic effects on hypothalamic neurons and demonstrated its broader implications in metabolic health.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
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.