reversed-phase HPLC 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 2025-08-15. 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.
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.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
| 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 |
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.
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.
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Lung fibrosis is a recognized complication of rheumatoid arthritis. It is also a rare but well-recognized consequence of medications used to treat RA such as methotrexate and leflunomide). Caplan's syndrome describes lung nodules in individuals with RA and additional exposure to coal dust. Exudative pleural effusions are also associated with RA.
An association between osteoporosis, another disease characterized by the degradation of bony tissue, and sarcopenia, the age-related degeneration of muscle mass and quality have also been found. Whether this link is a result of direct regulation or a secondary effect through muscle mass is not known. A link in mice between the concentration of myostatin in the prenatal environment and the strength of offspring's bones, partially counteracting the effects of osteogenesis imperfecta (brittle bone disease) has been found. Osteogenesis imperfecta is due to a mutation that causes the production of abnormal Type I collagen. Mice with defective myostatin were created by replacing sequences coding for the C-terminal region of myostatin with a neomycin cassette, rendering the protein nonfunctional. By crossbreeding mice with the abnormal Type I collagen and those with the knockout myostatin, the offspring had "a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure" of their femurs as compared to the other mice with osteogenesis imperfecta, showing the positive effects of decreased myostatin on bone strength and formation.
=== Prevention and patient education === Early recognition and knowledge of the onset of UCTD can help patients manage and control their disease. Patients should be informed of common agents and triggers to help manage symptoms, to shorten the duration of the disease, and prevent complications.
=== Cannabinoids in other plants === Phytocannabinoids occur in plants like Echinacea purpurea, Echinacea angustifolia, Acmella oleracea, Helichrysum umbraculigerum, and Radula marginata. Echinacea species contain Anandamide-like alkylamides, with at least 25 identified, some showing affinity for CB2 receptors. These are concentrated in roots and flowers. Yangonin in kava has significant CB1 receptor affinity. Tea (Camellia sinensis) catechins show affinity for human cannabinoid receptors. Beta-caryophyllene, a terpene in cannabis and other plants, is a selective CB2 receptor agonist. Black truffles contain anandamide. Perrottetinene, a moderately psychoactive cannabinoid, is found in Radula varieties. Machaeriol A and related compounds occur in Machaerium plants. Most phytocannabinoids are nearly insoluble in water but soluble in lipids, alcohols, and other non-polar organic solvents.
The United States is home to a wide variety of ethnic groups, traditions, and customs. The country has been described as having the values of individualism and personal autonomy, as well as a strong work ethic and competitiveness. Voluntary altruism toward others also plays a major role; according to a 2016 study by the Charities Aid Foundation, Americans donated 1.44% of total GDP to charity—the highest rate in the world by a large margin. Americans have traditionally been characterized by a unifying political belief in an "American Creed" that emphasizes consent of the governed, liberty, equality under the law, democracy, social equality, property rights, and a preference for limited government. The U.S. has acquired significant hard and soft power through its diplomatic influence, economic power, military alliances, and cultural exports such as American movies, music, video games, sports, and food. The influence that the United States exerts on other countries through soft power is referred to as Americanization. Nearly all present Americans or their ancestors came from Europe, Africa, or Asia (the "Old World") within the past five centuries. Mainstream American culture is a Western culture largely derived from the traditions of European immigrants with influences from many other sources, such as traditions brought by slaves from Africa.
Sources: en.wikipedia.org
=== Improvement === To help promote and expand the adoption of health information technology, Congress passed the HITECH act as part of the American Recovery and Reinvestment Act of 2009. HITECH stands for Health Information Technology for Economic and Clinical Health Act. It gave the department of health and human services the authority to improve healthcare quality and efficiency through the promotion of health IT. The act provided financial incentives or penalties to organizations to motivate healthcare providers to improve healthcare. The purpose of the act was to improve quality, safety, efficiency, and ultimately to reduce health disparities. One of the main parts of the HITECH act was setting the meaningful use requirement, which required EHRs to allow for the electronic exchange of health information and to submit clinical information. The purpose of HITECH is to ensure the sharing of electronic information with patients and other clinicians are secure. HITECH also aimed to help healthcare providers have more efficient operations and reduce medical errors. The program consisted of three phases. Phase one aimed to improve healthcare quality, safety and efficiency. Phase two expanded on phase one and focused on clinical processes and ensuring the meaningful use of EHRs. Lastly, phase three focused on using Certified Electronic Health Record Technology (CEHRT) to improve health outcomes. In 2014, the implementation of electronic records in US hospitals rose from a low percentage of 10% to a high percentage of 70%.
== Chemistry == With a formula of C17H19NO3 and a molecular weight of 285.343, both identical to morphine, hydromorphone can be considered a structural isomer of morphine and is a hydrogenated ketone thereof. Hydromorphone is made from morphine either by direct re-arrangement (made by reflux heating of alcoholic or acidic aqueous solution of morphine in the presence of platinum or palladium catalyst) or reduction to dihydromorphine (usually via catalytic hydrogenation), followed by oxidation with benzophenone in presence of potassium tert-butoxide or aluminium tert-butoxide (Oppenauer oxidation). The 6 ketone group may be replaced with a methylene group via the Wittig reaction to produce 6-methylenedihydrodesoxymorphine, which is 80 times stronger than morphine. Hydromorphone is more soluble in water than morphine; therefore, hydromorphone solutions may be produced to deliver the drug in a smaller volume of water. The hydrochloride salt is soluble in three parts of water, whereas a gram of morphine hydrochloride dissolves in 16 ml of water; for all common purposes, the pure powder for hospital use can be used to produce solutions of virtually arbitrary concentration. When the powder appeared on the street, this very small volume of powder needed for a dose means that overdoses are likely for those who mistake it for heroin or other powdered narcotics, especially those that have been diluted prior to consumption.
=== Royalty litigation === In March 2003, Cambridge Antibody Technology (CAT) stated its wish to "initiate discussions regarding the applicability of the royalty offset provisions for Humira" with Abbott Laboratories in the High Court of London. In November 2004, the trial began, and in December 2004, Justice Hugh Laddie ruled for CAT. A short version of the full statement of the proceedings was released. In it Justice Laddie remarked, "Abbott was in error when it made its first royalty payment to CAT calculated on the basis that only 2% of the Net Sales was due. It should have calculated on the basis of the full royalty of just over 5% and should have paid and continued to pay CAT accordingly." Justice Laddie went on to observe "...that the construction advanced by Abbott does violence to the language of the agreements, renders them obscure and makes little or no commercial sense. For this reason CAT wins the action." Abbott was required to pay CAT US$255 million, some of which was to be passed to its partners in development. Of this sum, the Medical Research Council received US$191 million, and in addition, Abbott was asked to pay the MRC a further US$7.5 million over five years from 2006, providing that Humira remains on the market. The MRC also is to receive a further £5.1 million (sterling) in respect of past royalties.
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== Nomenclature == Various names have been applied to the undeclared conflict waged by South Africa in Angola and Namibia (then South West Africa) from the mid 1960s to the late 1980s. The term "South African Border War" has typically denoted the military campaign launched by the People's Liberation Army of Namibia (PLAN), which took the form of sabotage and rural insurgency, as well as the external raids launched by South African troops on suspected PLAN bases inside Angola or Zambia. These occasionally provoked conventional engagements with the Zambian National Defence Force (ZNDF) and the People's Armed Forces of Liberation of Angola (FAPLA). The strategic situation was further complicated by the fact that South Africa occupied large swathes of Angola for extended periods in support of the National Union for the Total Independence of Angola (UNITA), making the "Border War" an increasingly inseparable conflict from the parallel Angolan Civil War. "Border War" entered public discourse in South Africa during the late 1970s; the term was adopted thereafter by the country's ruling National Party. Due to the covert nature of most South African Defence Force (SADF) operations inside Angola, the term was favoured as a means of omitting any reference to engagements on foreign soil. Where tactical aspects of various engagements were discussed, some contemporary historians simply identified the conflict as the "bush war".
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.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.