Regulatory peptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-03-27 and is reviewed periodically as new material appears.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
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.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
== History == Clomipramine was developed by Geigy as a chlorinated derivative of imipramine. It was first referenced in the literature in 1961 and was patented in 1963. The drug was first approved for medical use in Europe in the treatment of depression in 1970, and was the last of the major TCAs to be marketed. In fact, clomipramine was initially considered to be a "me-too drug" by the FDA, and in relation to this, was declined licensing for depression in the United States. As such, to this day, clomipramine remains the only TCA that is available in the United States that is not approved for the treatment of depression, in spite of the fact that it is a highly effective antidepressant. Clomipramine was eventually approved in the United States for the treatment of OCD in 1989 and became available in 1990. It was the first drug to be investigated and found effective in the treatment of OCD. The benefits in OCD were first reported by Juan José López-Ibor in 1967, and the first double-blind, placebo-controlled clinical trial of clomipramine for OCD was conducted in 1976, with more rigorous clinical studies that solidified its effectiveness conducted in the 1980s. It remained the "gold standard" for the treatment of OCD for many years until the introduction of the SSRIs, which have since largely superseded it due to greatly improved tolerability and safety (although notably not effectiveness).
BMS-986121: μ-PAM BMS-986122: μ-PAM BPRMU191: confers agonistic properties to small-molecule morphinan antagonists Ignavine Oxytocin: μ-PAM δ-PAM (see reference) Cannabidiol Tetrahydrocannabinol Sodium (Na+)
Lean MASLD affects between 10 and 20% of Americans and Europeans, and approximately 25% of Asians, although some countries have a higher incidence (e.g., India has a very high proportion of lean MASLD and almost no obese MASLD). PNPLA3 may be relevant for the progression of MASLD in lean people. Thus, people with MASLD deserve consideration for treatment regardless of the presence or absence of obesity. In children ages 1 to 19, the prevalence was found to be approximately 8% in the general population, up to 34% in studies with data from child obesity clinics. The majority of cryptogenic cirrhosis is believed to be due to MASH. MASFLD prevalence is expected to increase steadily, from 25% in 2018 to a projected 33.5% of people with MASLD globally in 2030, and from 20% to a projected 27% of those with MASLD will progress to MASH.
Examples of potent CYP1A2 inhibitors include ethinylestradiol (found in hormonal birth control), fluoroquinolones (e.g., ciprofloxacin), fluvoxamine, and St. John's wort, while potent CYP1A2 inducers include phenytoin, rifampin, ritonavir, and tobacco. A study found that ritonavir, a strong CYP3A4 and CYP2D6 inhibitor and moderate CYP1A2 inducer, increased trazodone peak levels by 1.4-fold, trazodone area-under-the-curve levels by 2.4-fold, and decreased trazodone clearance by 50%. This was associated with adverse effects such as nausea, hypotension, and syncope. Another study found that the strong CYP3A4 inducer carbamazepine reduced concentrations of trazodone by 60 to 74%. The strong CYP2D6 inhibitor thioridazine has been reported to increase trazodone levels by 1.4-fold and concentrations of mCPP by 1.5-fold. Fluoxetine, a strong inhibitor of CYP2D6 and a weak or moderate inhibitor of CYP3A4, has been reported to increase levels of trazodone by 1.3- to 1.7-fold and of mCPP by 3.0- to 3.4-fold. Conversely, CYP2D6 genotype has not been found to predict trazodone or mCPP concentrations with trazodone therapy, although CYP2D6 genotype did correlate with side effects like dizziness and prolonged corrected QT interval. Smokers have lower levels of trazodone and higher ratios of mCPP to trazodone. Trazodone levels were 30% lower in smokers and mCPP to trazodone ratio was 1.3-fold higher in smokers, whereas mCPP concentrations were not different between smokers and non-smokers. Smoking is known to induce CYP1A2, and this may be involved in these findings.
Sources: en.wikipedia.org
Total synthesis, a specialized area within organic chemistry, focuses on constructing complex organic compounds, especially those found in nature, using laboratory methods. It often involves synthesizing natural products from basic, commercially available starting materials. Total synthesis targets can also be organometallic or inorganic. While total synthesis aims for complete construction from simple starting materials, modifying or partially synthesizing these compounds is known as semisynthesis. Natural product synthesis serves as a critical tool across various scientific fields. In organic chemistry, it tests new synthetic methods, validating and advancing innovative approaches. In medicinal chemistry, natural product synthesis is essential for creating bioactive compounds, driving progress in drug discovery and therapeutic development. Similarly, in chemical biology, it provides research tools for studying biological systems and processes. Additionally, synthesis aids natural product research by helping confirm and elucidate the structures of newly isolated compounds. The field of natural product synthesis has progressed remarkably since the early 19th century, with improvements in synthetic techniques, analytical methods, and an evolving understanding of chemical reactivity. Today, modern synthetic approaches often combine traditional organic methods, biocatalysis, and chemoenzymatic strategies to achieve efficient and complex syntheses, broadening the scope and applicability of synthetic processes.
The current epidemic of opioid abuse is the most lethal drug epidemic in U.S. history. The crisis can be distinguished by waves of opioid overdose deaths as described by the Centers of Disease Control and Prevention. The first wave began in the 1990s, related to the rise in prescriptions of natural opioids (such as codeine and morphine), semisynthetic opioids (oxycodone, hydrocodone, hydromorphone, and oxymorphone), and synthetic opioids like methadone. In the U.S., "the age-adjusted drug poisoning death rate involving opioid analgesics increased from 1.4 to 5.4 deaths per 100,000 population between 1999 and 2010". The second wave dates to around 2010 with the rapid increase in opioid overdoses due to heroin. By this time, there were already four times as many deaths by overdose than in 1999. The age-adjusted drug poisoning death rate involving heroin doubled from 0.7 to 1.4 deaths per 100,000 people between 1999 and 2011 and continued to increase to 4.1 in 2015. The third wave of overdose deaths began in 2013, related to synthetic opioids, particularly illicitly produced fentanyl. While the illicit fentanyl market has continuously changed, the drug is generally sold as an adulterant in heroin. Research suggests that the rapid increase of fentanyl into the illicit opioid market has been largely supply-side-driven and dates to 2006.
== Research == Blisibimod, an inhibitor of both soluble and membrane-bound BAFF, has demonstrated similar reductions of B cells in clinical trials and is being investigated in a Phase II clinical study for patients with lupus. BR3-Fc, a recombinant fusion protein built with the extracellular ligand-binding portion of BAFF-R, blocks activation of this receptor by BLyS and is in early-stage pharmaceutical development. Rituximab, an anti-CD20 monoclonal antibody, has been approved for some indications. Ocrelizumab, ofatumumab, and "third-generation" anti-CD20 monoclonals are in development. Other drugs addressing B lymphocyte hyperactivity include atacicept, a recombinant fusion protein that is built with the extracellular ligand binding portion of TACI and blocks activation of TACI by APRIL and BLyS. It failed a Phase II trial for multiple sclerosis.
The compounds of sulfur and iodine are recovered and reused, hence the process is called the sulfur–iodine cycle. This process is endothermic and must occur at high temperatures, so energy in the form of heat has to be supplied. The sulfur–iodine cycle has been proposed as a way to supply hydrogen for a hydrogen-based economy. It is an alternative to electrolysis, and does not require hydrocarbons like current methods of steam reforming. But note that all of the available energy in the hydrogen so produced is supplied by the heat used to make it.
Colonial: small, regular groups of motile cells Capsoid: individual non-motile cells embedded in mucilage Coccoid: individual non-motile cells with cell walls Palmelloid: nonmotile cells embedded in mucilage Filamentous: a string of connected nonmotile cells, sometimes branching Parenchymatous: cells forming a thallus with partial differentiation of tissues In three lines, even higher levels of organization have been reached, with full tissue differentiation. These are the brown algae,—some of which may reach 50 m in length (kelps)—the red algae, and the green algae. The most complex forms are found among the charophyte algae (see Charales and Charophyta), in a lineage that eventually led to the higher land plants. The innovation that defines these nonalgal plants is the presence of female reproductive organs with protective cell layers that protect the zygote and developing embryo. Hence, the land plants are referred to as the Embryophytes.
Sources: en.wikipedia.org
The modern method of embalming involves the injection of various chemical solutions into the arterial network of the body to primarily disinfect and slow the decomposition process. William Harvey, the 17th century English physician who was the first to detail the system of blood circulation, made his discoveries by injecting colored solutions into corpses. The Scottish surgeon William Hunter was the first to apply these methods to the art of embalming as part of mortuary practice. He wrote a widely read report on the appropriate methods for arterial and cavity embalming in order to preserve bodies for burial. His brother, John Hunter, applied these methods and advertised his embalming services to the general public from the mid-18th century. One of his more notorious clients was dentist Martin Van Butchell. When his wife Mary died on 14 January 1775, he had her embalmed as an attraction to draw more customers. Hunter injected the body with preservatives and color additives that gave a glow to the corpse's cheeks, replaced her eyes with glass eyes, and dressed her in a fine lace dress. The body was embedded in a layer of plaster of Paris in a glass-topped coffin. Butchell exhibited the body in the window of his home and many Londoners came to see it; however, Butchell drew criticism for the display. A rumor, possibly started by Butchell himself, claimed that his wife's marriage certificate had specified that her husband would only have control over her estate after her death for as long as her body was kept unburied.
== Published works == A Method for Identifying the Photoproducts, Mechanisms, and Toxicity of Petroleum from the Deepwater Horizon by High-Performance Liquid Chromatography, DNPHi Derivatization, and Solar Simulation
=== Pharmaceuticals === Ion-exchange resins are used in the manufacturing of pharmaceuticals, not only for catalyzing certain reactions, but also for isolating and purifying pharmaceutical active ingredients. Three ion-exchange resins, sodium polystyrene sulfonate, colestipol, and cholestyramine, are used as active ingredients. Sodium polystyrene sulfonate is a strongly acidic ion-exchange resin and is used to treat hyperkalemia. Colestipol is a weakly basic ion-exchange resin and is used to treat hypercholesterolemia. Cholestyramine is a strongly basic ion-exchange resin and is also used to treat hypercholesterolemia. Colestipol and cholestyramine are known as bile acid sequestrants. Ion-exchange resins are also used as excipients in pharmaceutical formulations such as tablets, capsules, gums, and suspensions. In these uses the ion-exchange resin can have several different functions, including taste-masking, extended release, tablet disintegration, increased bioavailability, and improving the chemical stability of the active ingredients. Selective polymeric chelators have been proposed for maintenance therapy of some pathologies, where chronic ion accumulation occurs, such as Wilson disease (where copper accumulation occurs) or hereditary hemochromatosis (iron overload, where iron accumulation occurs) These polymers or particles have a negligible or null systemic biological availability and they are designed to form stable complexes with Fe2+ and Fe3+ in the GIT and thus limiting the uptake of these ions and their long-term accumulation.
electron pair Two electrons which occupy the same molecular orbital but have opposite spins. Electron pairs form chemical bonds or occur as lone pairs of valence electrons; it is also possible for electrons to occur individually as unpaired electrons.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
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.