heptapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-05-06. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
| 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 |
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
== Distribution == Rotheca myricoides is native to mountains from Eritrea to South Africa. It is native to Angola, Botswana, Burundi, Caprivi Strip, Democratic Republic of the Congo, Djibouti, Eswatini, Eritrea, Ethiopia, Kenya, KwaZulu-Natal, Malawi, Mozambique, Namibia, Northern Provinces, Rwanda, Somalia, Sudan, Tanzania, Uganda, Zambia, and Zimbabwe. It was introduced to Trinidad-Tobago, Australia, and Brazil.
To be more specific, there are hopes to identify what specific chromosomes are damaged, and to define the damage, during cancer development from proton exposure. Another study looks into determining "the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, and spatial learning and memory as measured by the Morris water maze. Electrical charging of a spacecraft due to interplanetary proton bombardment has also been proposed for study. There are many more studies that pertain to space travel, including galactic cosmic rays and their possible health effects, and solar proton event exposure. The American Biostack and Soviet Biorack space travel experiments have demonstrated the severity of molecular damage induced by heavy ions on microorganisms including Artemia cysts.
=== Fencing === The sport reached its peak during the 2020 and 2024 Olympic Games. Cheung Ka-long became a national icon by winning back-to-back gold medals in men's individual foil, while Vivian Kong secured gold in women's individual épée in Paris 2024.
Twenty of Bukele's governmental institutions were investigated by the office of the attorney general in November 2020 for corruption related to the COVID-19 pandemic, but the investigations were halted after the attorney general was removed by the Legislative Assembly on 1 May 2021. The United States has placed sanctions on several of Bukele's government officials, labeling them as corrupt. The officials include Javier Argueta (presidential advisor), Osiris Luna Meza (general director of penal centers), Carlos Marroquín Chica (chairman of the Social Fabric Reconstruction Unit), Martha Carolina Recinos (chief of the cabinet), Rogelio Rivas (former minister of justice), Ernesto Sanabria (press secretary), and Alejandro Zelaya (former minister of finance). The U.S. also considered some of Bukele's Legislative Assembly allies corrupt, including Guillermo Gallegos and Christian Guevara. Some of the individuals are included on the U.S. State Department's "Engel List" of Central American politicians and judges considered "corrupt and undemocratic". Bukele called the sanctions and labels "absurd". In May 2021, the United States diverted El Salvador funding from government institutions to civil society groups to combat perceived corruption in Bukele's government. On 11 November 2021, Bukele introduced the "Foreign Agents Law" to the Legislative Assembly with the goal of "prohibiting foreign interference" in Salvadoran political affairs.
Sources: en.wikipedia.org
This error is quite small for nearly all mixing of naturally occurring isotope values, even for hydrogen which can have quite large natural variations in δ values. The estimation is usually avoided when unnaturally large δ values are encountered, which is especially common in isotopic labeling experiments.
== Medical use == Branched-chain alpha-keto acids such as α-KIC are found in high concentrations in the urine of people who suffer from Maple Syrup Urine Disease. This is disease is caused by a partial branched-chain alpha-keto acid dehydrogenase deficiency, which leads to a buildup of branched-chain alpha-keto acids, including α-KIC and HMB. These keto-acids build up in the liver, and since limited isovaleryl-CoA can be produced, these keto-acids must be excreted in the urine as α-KIC, HMB, and many other similar keto acids. Flare-ups in people who have this condition are caused due to poor diet. Symptoms of Maple Syrup Urine Disease include sweet smelling urine, irritability, lethargy, and in serious cases edema of the brain, apnea, coma, or respiratory failure. Treatment includes lowering leucine intake and a specialized diet to make up for the lack of leucine ingestion.
In the aftermath of the war, an imperial administration freed from accountability to a domestic electorate set about reconstructing an economy that was by then predicated unambiguously on gold. At the same time, British civil servants, municipal officials, and their cultural adjuncts were hard at work in the heartland of the former Boer Republics helping to forge new identities—first as 'British South Africans' and then, later still, as 'white South Africans'. Some scholars identify these new identities as partly underpinning the act of union that followed in 1910. Although challenged by a Boer rebellion only four years later, they did much to shape South African politics between the two world wars and to the present day. Many Boers referred to the war as the second of the Freedom Wars. The most resistant of Boers wanted to continue the fight and were known as "Bittereinders" (or irreconcilables) and at the end of the war some Boer fighters such as Deneys Reitz chose exile rather than sign an oath, like the following, to pledge allegiance to Britain:
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.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.