A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-28. Anything still debated is marked as such rather than presented as settled.
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.
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.
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 |
|---|---|---|
| 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 |
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
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.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a red or scaly patch of skin. In those with distant spread of the disease, there may be bone pain, swollen lymph nodes, shortness of breath, or yellow skin. Risk factors for developing breast cancer include obesity, a lack of physical exercise, alcohol consumption, hormone replacement therapy during menopause, ionizing radiation, an early age at first menstruation, having children late in life (or not at all), older age, having a prior history of breast cancer, and a family history of breast cancer. About five to ten percent of cases are the result of an inherited genetic predisposition, including BRCA mutations among others. Breast cancer most commonly develops in cells from the lining of milk ducts and the lobules that supply these ducts with milk. Cancers developing from the ducts are known as ductal carcinomas, while those developing from lobules are known as lobular carcinomas. There are more than 18 other sub-types of breast cancer. Some, such as ductal carcinoma in situ, develop from pre-invasive lesions. The diagnosis of breast cancer is confirmed by taking a biopsy of the concerning tissue. Once the diagnosis is made, further tests are carried out to determine if the cancer has spread beyond the breast and which treatments are most likely to be effective.
==== Elimination ==== MDMA and metabolites are primarily excreted as conjugates, such as sulfates and glucuronides. MDMA is a chiral compound and has been almost exclusively administered as a racemate. However, the two enantiomers have been shown to exhibit different kinetics. The disposition of MDMA may also be stereoselective, with the S-enantiomer having a shorter elimination half-life and greater excretion than the R-enantiomer. Evidence suggests that the area under the blood plasma concentration versus time curve (AUC) was two to four times higher for the (R)-enantiomer than the (S)-enantiomer after a 40 mg oral dose in human volunteers. Likewise, the plasma half-life of (R)-MDMA was significantly longer than that of the (S)-enantiomer (5.8 ± 2.2 hours vs 3.6 ± 0.9 hours). However, because MDMA excretion and metabolism have nonlinear kinetics, the half-lives would be higher at more typical doses (100 mg is sometimes considered a typical dose).
=== Allegations of manufacturing and product tampering === 26 April 2007 and 27 April 2007 recalls by Blue Buffalo, Diamond, Harmony Farms, and Natural Balance are claimed by all 4 brands to be due to unauthorized inclusion of rice protein by American Nutrition, Inc. (ANI), their manufacturer. This adds a new potential source of contamination and distrust, namely non-compliant contract manufacturers, beyond the original problematic Chinese ingredient suppliers. Diamond and Natural Balance refer to this as a "manufacturing deviation" by ANI. Blue Buffalo and Harmony Farms characterize this as "product tampering" by ANI. ANI's recall notice makes no comment on these allegations.
He also served as a member of the executive committee of the American Society for Testing and Materials (A.S.T.M.) Committee E-19 on Chromatography (1966–1973); as a foreign member of the executive committee of the (British) Chromatographic Society (1992–1997); and as an executive committee member of the Chromatography Subdivision of the Division of Analytical Chemistry of the American Chemical Society (A.C.S.).
Sources: en.wikipedia.org
=== Prescription drug history === Antibiotics first arrived on the medical scene in 1932 thanks to Gerhard Domagk; and were coined the "wonder drugs". The introduction of the sulfa drugs led to the mortality rate from pneumonia in the U.S. to drop from 0.2% each year to 0.05% (i.e., 1⁄4 as much) by 1939. Antibiotics inhibit the growth or the metabolic activities of bacteria and other microorganisms by a chemical substance of microbial origin. Penicillin, introduced a few years later, provided a broader spectrum of activity compared to sulfa drugs and reduced side effects. Streptomycin, found in 1942, proved to be the first drug effective against the cause of tuberculosis and also came to be the best known of a long series of important antibiotics. A second generation of antibiotics was introduced in the 1940s: aureomycin and chloramphenicol. Aureomycin was the best known of the second generation. Lithium was discovered in the 19th century for nervous disorders and its possible mood-stabilizing or prophylactic effect; it was cheap and easily produced. As lithium fell out of favor in France, valpromide came into play. This antibiotic was the origin of the drug that eventually created the mood stabilizer category. Valpromide had distinct psychotrophic effects that were of benefit in both the treatment of acute manic states and in the maintenance treatment of manic depression illness. Psychotropics can either be sedative or stimulant; sedatives aim at damping down the extremes of behavior. Stimulants aim at restoring normality by increasing tone.
=== Annealing based connection of oligonucleotides === Usually, a set of individually designed oligonucleotides is made on automated solid-phase synthesizers, purified and then connected by specific annealing and standard ligation or polymerase reactions. To improve specificity of oligonucleotide annealing, the synthesis step relies on a set of thermostable DNA ligase and polymerase enzymes. To date, several methods for gene synthesis have been described, such as the ligation of phosphorylated overlapping oligonucleotides, the Fok I method and a modified form of ligase chain reaction for gene synthesis. Additionally, several PCR assembly approaches have been described. They usually employ oligonucleotides of 40-50 nucleotides length that overlap each other. These oligonucleotides are designed to cover most of the sequence of both strands, and the full-length molecule is generated progressively by overlap extension (OE) PCR, thermodynamically balanced inside-out (TBIO) PCR or combined approaches. The most commonly synthesized genes range in size from 600 to 1,200 bp although much longer genes have been made by connecting previously assembled fragments of under 1,000 bp. In this size range it is necessary to test several candidate clones confirming the sequence of the cloned synthetic gene by automated sequencing methods.
Hydrocodone/paracetamol (also known as hydrocodone/acetaminophen) is the combination of the pain medications hydrocodone (an opioid) and paracetamol (acetaminophen). It is used to treat moderate to severe pain. It is taken by mouth. Recreational use is common in the United States. Common side effects include dizziness, sleepiness, constipation, and vomiting. Serious side effects include addiction, decreased rate of breathing, low blood pressure, severe allergic reactions, and liver failure. Use during pregnancy may harm the fetus. Use with alcohol is not recommended. Hydrocodone works by binding to the mu-opioid receptor. How paracetamol works is unclear but may involve blocking the creation of prostaglandins. Hydrocodone/paracetamol was approved for medical use in the United States in 1982. In the United States, it is a schedule II controlled substance. In 2023, it was the 25th most commonly prescribed medication in the United States, with more than 21 million prescriptions. It is not available in the United Kingdom, though the combination codeine/paracetamol (co-codamol) is. It is sold under the brand names Vicodin and Norco among others.
== History == Two main studies showed that treosulfan is at least as effective as busulfan, another medicine used to prepare people for haematopoietic stem cell transplantation. In one of the studies, involving 570 adults with acute myeloid leukaemia (a blood cancer) or myelodysplastic syndromes (conditions in which large numbers of abnormal blood cells are produced), 64% of patients given treosulfan (with fludarabine) had a successful transplant and were alive and disease-free after 2 years, compared with 51% of patients given busulfan (with fludarabine). In an additional study in 70 children with blood cancers, 99% of children given treosulfan (with fludarabine) were alive three months after their transplant. Efficacy was evaluated in MC-FludT.14/L Trial II (NCT00822393), a randomized active-controlled trial comparing treosulfan to busulfan with fludarabine as a preparative regimen for allogeneic transplantation. Eligible patients included adults 18 to 70 years old with AML or MDS, Karnofsky performance status ≥ 60%, and age ≥ 50 years or hematopoietic cell transplantation comorbidity index [HCTCI] score > 2. There were 570 patients randomized to treosulfan (n=280) or busulfan (n=290).
In biochemistry, the most prevalent, internationally accepted system of nomenclature for fatty acids is defined by the International Union of Pure and Applied Chemistry (IUPAC). Herein, the ω-x system (also known as the omega x or n-x system) establishes that fatty acids can be identified through the following formation: C:Dω–x where C is the total number of carbons, D is the number of double bonds, and ω–x indicates the position of the first double bond, counting from the –CH3 end of the fatty acid. The ω–x system curbs ambiguity regarding SFAs and MUFAs, as it specifically denotes both the carbon and unsaturation numbers, as well as the location of the double bond (i.e., for MUFAs). Equally, ω–x nomenclature is widely used for PUFAs, particularly for those wherein two consecutive double bonds are consistently separated by a methylene group (–CH2–). However, several PUFAs contain double bonds that are not always interrupted by a methylene group, and thus the ω–x system fails to establish the specific position of all double bonds about PUFA chains. As such, these atypical PUFAs are generically referred to as "non-methylene interrupted" (NMI) fatty acids, and are commonly found in lipids from marine invertebrates.
Sources: en.wikipedia.org
{\displaystyle {\ce {AB + C <=> AC + B}};\quad K_{\rm {B,C}}={\frac {{\ce {[AC][B]}}}{{\ce {[AB][C]}}}}={\frac {K_{\rm {AC}}{\ce {[A][B][C]}}}{K_{\rm {AB}}{\ce {[A][B][C]}}}}={\frac {K_{\rm {AC}}}{K_{\rm {AB}}}}}
== AFL career == Steinberg was selected by Essendon with the thirty-first pick in the 2010 AFL draft in November 2010. Ariel was drafted from the Bendigo Pioneers in the TAC Cup having joined the Pioneers squad halfway through the 2010 season. He started playing for the Bendigo Bombers in their 2011 season. He kicked 3 goals against Frankston on 17 April 2011. He kicked 5 goals against the Box Hill Hawks on 19 June 2011. He kicked four goals against the Werribee Tigers on 7 August 2011. He kicked three goals against the Northern Bullants on 4 September 2011. He scored 25 goals in 2011. He was delisted in October 2015. Steinberg, along with 33 other Essendon players, was found guilty of using a banned performance-enhancing substance, thymosin beta-4, as part of Essendon's sports supplements program during the 2012 season. He and his teammates were initially found not guilty in March 2015 by the AFL Anti-Doping Tribunal, but a guilty verdict was returned in January 2016 after an appeal by the World Anti-Doping Agency. He was suspended for two years which, with backdating, ended in November 2016; as a result, he served approximately fourteen months of his suspension and missed the entire 2016 VFL season, during which time he had intended to play for VFL club Williamstown.
== Examples == A particular example of rational drug design involves the use of three-dimensional information about biomolecules obtained from such techniques as X-ray crystallography and NMR spectroscopy. Computer-aided drug design in particular becomes much more tractable when there is a high-resolution structure of a target protein bound to a potent ligand. This approach to drug discovery is sometimes referred to as structure-based drug design. The first unequivocal example of the application of structure-based drug design leading to an approved drug is the carbonic anhydrase inhibitor dorzolamide, which was approved in 1995. Another case study in rational drug design is imatinib, a tyrosine kinase inhibitor designed specifically for the bcr-abl fusion protein that is characteristic for Philadelphia chromosome-positive leukemias (chronic myelogenous leukemia and occasionally acute lymphocytic leukemia). Imatinib is substantially different from previous drugs for cancer, as most agents of chemotherapy simply target rapidly dividing cells, not differentiating between cancer cells and other tissues. Additional examples include:
Unlike most modern eggs, many non-avian dinosaur eggs had a rough texture formed by nodes and ridges ornamenting the surface of their shell. This is predominant in Cretaceous dinosaur eggs, but very rare in eggs from the Jurassic or Triassic. Because of the lack of modern analogues, the purpose of eggshell ornamentation is unknown, but many functions have been proposed. Possibly, they provided extra strength to the eggshell without having pore canals too long for adequate gas exchange. They could also have helped keep substrate away from the pore openings of eggs that were buried, but modern turtles and crocodylians which bury their eggs have smooth eggshells, so this adaptation is not necessary for animals which bury their eggs. Another hypothesis, proposed by R. M. Mellon in 1982 in his senior thesis at Princeton University, is that the ridges and nodes would have formed pathways for gas to flow across the surface of the eggshell, preventing accumulation of too much CO2 and aiding the flow of oxygen and water vapor. Since it varies from egg to egg, the texture of an eggshell's ornamentation is useful for classification. Six types of ornamentation were catalogued by Carpenter in 1999:
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.
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.