A practical reference on Heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-12. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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 |
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.
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.
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.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
a known amount of anti-HbA1c antibody is added to the sample because only one binding site is available per HbA1c molecule (the glycated N-terminal valine on a beta chain), the antibody-HbA1c complex is small and soluble excess polyhapten is added to the sample. The polyhapten is several HbA1c-like epitopes bound together excess antibody cross-links with the polyhapten and forms large complexes which are insoluble and make the solution turbid Turbidity is inversely proportional to HbA1c concentration Concentration of HbA1c divided by concentration of total Hb (e.g. measured by absorptiometry) gives a percentage HbA1c
Phalloidin is much smaller than an antibody that would typically be used to label cellular proteins for fluorescent microscopy which allows for much denser labeling of filamentous actin and much more detailed images can be acquired particularly at higher resolutions. Unmodified phalloidins do not permeate cell membranes, making them less effective in experiments with living cells. Derivatives of phalloidin with greatly increased cell permeability have been synthesized. Cells treated with phalloidins exhibit a number of toxic effects and frequently die. Furthermore, phalloidin-treated cells will have greater levels of actin associated with their plasma membranes, and the microinjection of phalloidin into living cells will change actin distribution as well as cell motility.
==== Medicine ==== Australia (Tasmania), Turkey and India are the major producers of poppy for medicinal purposes and poppy-based drugs, such as morphine or codeine. The New York Times reported, in 2014, that Tasmania was the largest producer of the poppy cultivars used for thebaine (85% of the world's supply) and oripavine (100% of the world's supply) production. Tasmania also had 25% of the world's opium and codeine production.
Sources: en.wikipedia.org
== Physiology == The body maintains a stable level of oxygen saturation for the most part by chemical processes of aerobic metabolism associated with breathing. Using the respiratory system, red blood cells, specifically the hemoglobin, gather oxygen in the lungs and distribute it to the rest of the body. The needs of the body's blood oxygen may fluctuate such as during exercise when more oxygen is required or when living at higher altitudes. A blood cell is said to be "saturated" when carrying a normal amount of oxygen. Both too high and too low levels can have adverse effects on the body.
7.46 mg dihydrocodeine as co-dydramol 7.46/500 (e.g. in the branded product Paramol). 10 mg dihydrocodeine as co-dydramol 10/500, this is also the preparation to be dispensed if no strength is specified on a prescription. 20 mg dihydrocodeine as co-dydramol 20/500 (e.g. branded products Paracod 500/20 and Remedeine). 30 mg dihydrocodeine as co-dydramol 30/500 (e.g. branded products Paracod 500/30 and Remedeine Forte).
Medicines are the world's largest fraud market, worth some $200 billion per year, making the widespread demand for a COVID‑19 vaccine vulnerable to counterfeit, theft, scams, and cyberattacks throughout the supply chain. The vaccine has been referred to as "the most valuable asset on earth"; Interpol called it "liquid gold" and warned of an "onslaught of all types of criminal activity". Anticorruption, transparency, and accountability safeguards are being established to reduce and eliminate corruption of COVID‑19 vaccine supplies. Absence of harmonized regulatory frameworks among countries, including low technical capacity, constrained access, and ineffective capability to identify and track genuine vs. counterfeit vaccines, may be life-threatening for vaccine recipients, and would potentially perpetuate the COVID‑19 pandemic. Tracking system technologies for packaging are being used by manufacturers to trace vaccine vials across the supply chain, and to use digital and biometric tools to assure security for vaccination teams. In December 2020, Interpol warned that organized crime could infiltrate the vaccine supply chain, steal product through physical means, and data theft, or even offer counterfeit vaccine kits. Further, vaccines which require constant freezing temperatures are also susceptible to sabotage. GPS devices will be used in the United States to track the vaccines.
Sources: en.wikipedia.org
== Illicit use == Dermorphin has been illegally used in horse racing as a performance-enhancing drug. Due to dermorphin's painkilling activity, horses treated with dermorphin may run harder than they would otherwise.
This is in contrast to many progestins, such as 19-nortestosterone derivatives (e.g., norethisterone, levonorgestrel, dienogest) and 17α-hydroxyprogesterone derivatives (e.g., cyproterone acetate, medroxyprogesterone acetate), which do bind to the AR and have been associated with significant androgenic or antiandrogenic effects depending on the progestin in question. Due to its lack of androgenic and antiandrogenic activity, and hence lack of masculinizing and feminizing effects, progesterone is one of the few progestogens that is suitable for use during pregnancy in women at risk for preterm birth or recurrent miscarriage.
== Analogues in non-vertebrate organisms == A variety of oxygen-transport and -binding proteins exist in organisms throughout the animal and plant kingdoms. Organisms including bacteria, protozoans, and fungi all have hemoglobin-like proteins whose known and predicted roles include the reversible binding of gaseous ligands. Since many of these proteins contain globins and the heme moiety (iron in a flat porphyrin support), they are often called hemoglobins, even if their overall tertiary structure is very different from that of vertebrate hemoglobin. In particular, the distinction of "myoglobin" and hemoglobin in lower animals is often impossible, because some of these organisms do not contain muscles. Or, they may have a recognizable separate circulatory system but not one that deals with oxygen transport (for example, many insects and other arthropods). In all these groups, heme/globin-containing molecules (even monomeric globin ones) that deal with gas-binding are referred to as oxyhemoglobins. In addition to dealing with transport and sensing of oxygen, they may also deal with NO, CO2, sulfide compounds, and even O2 scavenging in environments that must be anaerobic. They may even deal with detoxification of chlorinated materials in a way analogous to heme-containing P450 enzymes and peroxidases.
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.
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.