TKPRPGP 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 2026-04-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
| 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 |
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
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.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
Wilk noted how "brave whistleblowers from the lab risked their livelihoods to expose unlicensed lab techs sleeping on the job, a lack of supervision over untrained staff, contaminated tests, swapped samples, testing errors, a high rate of "inconclusive" results, and inaccurate results, with no process for addressing or rectifying errors" were subsequently "subject to litigation in response to their brave actions to expose the abuse of state funding in the lab, and the potential public health issues stemming from improperly processing and handling COVID 19 specimens." The bill passed unanimously in the California State Senate, but died in the California State Assembly. The CPDH partnership contract with PerkinElmer was terminated on May 15, 2022, and was subsequently criticized for its excess costs, failure to meet expectations, and the state's poor handling of the investigation.
== 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.
== Prognosis == As of 2015, 5-year survival rates for small cell lung cancer (extensive and limited) range between 3.6% and 32.2% for women, and between 2.2% and 24.5% for men. Relative 5-year survival rate for both sexes has increased from 3.6% in 1975 to 6.7% in 2014. In limited-stage disease, the relative 5-year survival rate (both sexes, all races, all ages) is 21.3%; however, women have higher 5-year survival rates, 26.9%, and men have lower survival rates, 21.3%. The prognosis is far grimmer in extensive-stage small-cell lung carcinoma where 5-year relative survival rate (both sexes, all races, all ages) is 2.8%; however, women have higher 5-year survival rates, 3.4%, and men have lower 5-year survival rates, 2.2%. Small-cell carcinoma is very responsive to chemotherapy and radiotherapy, and in particular, regimens based on platinum-containing agents. However, most people with the disease relapse, and median survival remains low. The overall incidence and mortality rates of SCLC in the United States have decreased during the past few decades. Long-term survival of more than 5 years can be achieved with proper treatment. According to the 17th World Conference on Lung Cancer (WCLC), "patients who received chest radiation and prophylactic cranial irradiation along with a mean of five chemotherapy cycles could achieve a median survival of more than 5 years." In some cases, long-term survival of 10+ years is achieved with chemotherapy and radiation alone. A 2023 article stated that the median overall survival is about 1 year, the worst of any lung cancer subtype.
=== Distillation of pyrite === Sulfuric acid created by Roebuck's process approached a 65% concentration. Later refinements to the lead chamber process by French chemist Joseph Louis Gay-Lussac and British chemist John Glover improved concentration to 78%. However, the manufacture of some dyes and other chemical processes require a more concentrated product. Throughout the 18th century, this could only be made by dry distilling minerals in a technique similar to the original alchemical processes. Pyrite (iron disulfide, FeS2) was heated in air to yield iron(II) sulfate, FeSO4, which was oxidized by further heating in air to form iron(III) sulfate, Fe2(SO4)3, which, when heated to 480 °C, decomposed to iron(III) oxide and sulfur trioxide, which could be passed through water to yield sulfuric acid in any concentration. However, the expense of this process prevented the large-scale use of concentrated sulfuric acid.
Algae ( AL-jee, UK also AL-ghee; sing.: alga ) are any of a large and diverse group of photosynthetic organisms. It excludes the land plants (embryophytes). Such organisms range from microscopic unicellular microalgae (including cyanobacteria and phytoplankton) to seaweeds, multicellular macroalgae which may grow up to 50 metres (160 ft) in length. Most algae are aquatic (especially marine), and some form cohesive colonies. Freshwater algae include Charophyta such as the filamentous Spirogyra and the grasslike stoneworts. Most algae are plankton carried passively by water, although some macroalgae have holdfasts for anchorage. Algae are polyphyletic as they have multiple evolutionary origins. Although algae with two-membraned chloroplasts seem to form a paraphyletic group within the clade Archaeplastida, other algae with chloroplasts that have three or more membranes evolved from protists that acquired photosynthesis after engulfing archaeplastids. Chlorophytes, rhodophytes (red algae) and glaucophytes (grey algae) have primary chloroplasts directly derived from endosymbiont cyanobacteria, while diatoms, cryptomonads, euglenoids and phaeophyceae (brown algae) have secondary chloroplasts derived from indirectly endosymbiont red algae or green algae. Most algae are single-celled organisms without roots, leaves, or stems. Most are photoautotrophs and the main primary producers of aquatic ecosystems, although some are mixotrophs that derive metabolic energy both from internal photosynthesis and from foraging external nutrients.
Sources: en.wikipedia.org
Cortisone is a naturally occurring, mostly inactive pregnene (21-carbon) steroid hormone. In the body, cortisone is produced as part of the cortisol–cortisone shunt, which protects vulnerable organs like the kidneys from cortisol. These organs produce the enzyme 11β-HSD2 which locally converts cortisol into inactive cortisone. Cortisone is later converted back into the active steroid cortisol by the enzyme 11β-HSD1, particularly in the liver, which maintains blood cortisol levels. Without the reaction converting cortisol into cortisone, cortisol binds with the mineralocorticoid receptors of the kidney, causing hypertension along with the other symptoms of apparent mineralocorticoid excess syndrome. Because it gets converted into cortisol by the body, it is sometimes used as a pharmaceutical prodrug as an alternative to directly taking cortisol. The term "cortisone" is frequently misused to mean either any corticosteroid or hydrocortisone, which is in fact cortisol. Many who speak of receiving a "cortisone shot" or taking "cortisone" are more likely receiving hydrocortisone or one of many other, much more potent synthetic corticosteroids. Cortisone can be administered as a prodrug, meaning it has to be converted by the body (specifically the liver, converting it into cortisol) after administration to be effective. It is used to treat a variety of ailments and can be administered intravenously, orally, intra-articularly (into a joint), or transcutaneously. Cortisone suppresses various elements of the immune system, thus reducing inflammation and attendant pain and swelling.
=== Available forms === Trimix is available in several different formulations, including a gel that can be used topically, a gel that can be administered into the urethra, and an injectable form that is administered via intracavernosal injection (an injection at either side, not the base, of the penis).
== Evolution of DNA == One of the challenges posed by the RNA world hypothesis is to discover the pathway by which an RNA-based system transitioned to one based on DNA. Geoffrey Diemer and Ken Stedman, at Portland State University in Oregon, may have found a solution. While conducting a survey of viruses in a hot acidic lake in Lassen Volcanic National Park, California, they uncovered evidence that a simple DNA virus had acquired a gene from a completely unrelated RNA-based virus. Virologist Luis P. Villarreal of the University of California Irvine also suggests that viruses capable of converting an RNA-based gene into DNA and then incorporating it into a more complex DNA-based genome might have been common in the virus world during the RNA to DNA transition some 4 billion years ago. This finding bolsters the argument for the transfer of information from the RNA world to the emerging DNA world before the emergence of the last universal common ancestor. From the research, the diversity of this virus world is still with us.
Doses of naltrexone of 25 to 150 mg/day have been found to produce significant increases in levels of β-endorphin, cortisol, and LH, equivocal changes in levels of prolactin and testosterone, and no significant changes in levels of adrenocorticotrophic hormone (ACTH) or follicle-stimulating hormone (FSH). Naltrexone influences the hypothalamic–pituitary–adrenal axis (HPA axis) probably through interference with opioid receptor signaling by endorphins. Blockade of MORs is thought to be the mechanism of action of naltrexone in the management of opioid dependence—it reversibly blocks or attenuates the effects of opioids. It is also thought to be involved in the effectiveness of naltrexone in alcohol dependence by reducing the euphoric effects of alcohol. The role of KOR modulation by naltrexone in its effectiveness for alcohol dependence is unclear but this action may also be involved based on theory and animal studies.
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.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.