Everything below concerns Selank. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
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.
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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.
Akinesia A loss or impairment of voluntary movement, often associated with Parkinson's disease and basal ganglia dysfunction. Allodynia A condition in which normally non-painful stimuli are perceived as painful, often due to nerve damage or sensitization. Alpha wave A type of brainwave oscillation in the frequency range of 8–13 Hz, commonly associated with relaxed, wakeful states and measured using electroencephalography (EEG). Alzheimer's disease A progressive neurodegenerative disorder characterized by memory loss, cognitive decline, and the presence of amyloid plaques and neurofibrillary tangles in the brain. Amygdala A brain structure involved in emotion, particularly fear, aggression, and emotional memory formation. It is part of the limbic system. Anencephaly A severe congenital condition in which a major portion of the brain, skull, and scalp is missing due to failed closure of the neural tube. Anhedonia The inability to experience pleasure, commonly associated with depression and certain neurological disorders. Anterograde amnesia A form of memory loss in which new memories cannot be formed following brain injury or trauma; often associated with damage to the hippocampus. Anterior cingulate cortex A region of the cingulate cortex implicated in functions such as emotion regulation, cognitive control, error detection, and decision-making. Aphasia A language disorder resulting from brain damage, most often in the left hemisphere, that affects the production or comprehension of speech and writing.
==== Mars landings ==== In 1971, the Soviet's Mars 2 successfully established Mars orbit and attempted a soft landing but crashed, becoming the first man-made object to impact Mars. This was shortly followed by Mars 3, a 358 kg lander, which successfully landed but the lander only transmitted data for 14.5 seconds before losing contact. In 1976, NASA followed suit, and put two successful landers on Mars. These were Viking 1 and Viking 2. These landers were significantly larger than the Soviet Mars landers (Viking 1 was 3,527 kilograms). They were able to take the first photographs from the surface of Mars. Viking 1 operated on the surface of Mars for around six years (On November 11, 1982, the Lander stopped operating after getting a faulty command) and Viking 2 for over three years (mission ended in early 1980). Both landers were equipped with a robotic sampler arm which successfully scooped up soil samples and tested them with instruments such as a Gas chromatography–mass spectrometer. The landers measured temperatures ranging from negative 86 degrees Celsius before dawn to negative 33 degrees Celsius in the afternoon. Both landers had issues obtaining accurate results from their seismometers. Photographs from the landers and orbiters surpassed expectations in quality and quantity. The total exceeded 4,500 from the landers and 52,000 from the orbiters.
The cell-extrinsic hallmarks of FLS in RA are: promotes osteoclastogenesis and bone erosion, contributes to cartilage degradation, induces synovial angiogenesis, and recruits and stimulates immune cells.
Sources: en.wikipedia.org
He made great use of trace evidence such as shoe and tire impressions, as well as fingerprints, ballistics and handwriting analysis, now known as questioned document examination. Such evidence is used to test theories conceived by the police, for example, or by the investigator himself. All of the techniques advocated by Holmes later became reality, but were generally in their infancy at the time Conan Doyle was writing. In many of his reported cases, Holmes frequently complains of the way the crime scene has been contaminated by others, especially by the police, emphasising the critical importance of maintaining its integrity, a now well-known feature of crime scene examination. He used analytical chemistry for blood residue analysis as well as toxicology examination and determination for poisons. He used ballistics by measuring bullet calibres and matching them with a suspected murder weapon.
== Reception == Even prior to its publication people drew comparisons to The Hunger Games, Harry Potter or the Twilight series. Half Bad has also been compared to Nineteen Eighty-Four by George Orwell. It had already broken two Guinness World Records as the most translated book – and the most translated children's book – by a debut author before publication. A Publishers Weekly starred review states, "This grim and thrilling tale, first in a planned trilogy, features understated prose that lets readers' imaginations fill in the blanks, as well as a well-developed sense of Witch culture. Nathan, the damaged survivor of horrific abuse, is an unforgettable protagonist, and Green expertly captures his torment at being caught between the mutually hostile sides of his heritage." Kirkus Reviews states, "Green propels Nathan forward with the help of often underdeveloped secondary characters, who are overshadowed by the imaginary relationship Nathan builds with his father; it is this that keeps both Nathan and readers going." In a review for Tor.com, Kat Kennedy writes, "Sally Green's Half Bad is the perfect novel for inspiring one to despise all of humanity or fall onto the ground and weep pathetically. Needless to say, it is an excellent book." In a review for The Guardian, Philip Womack writes, "While there is nothing new here, Half Bad's combination of themes will no doubt be entirely attractive to a large section of readers.
=== DNA hydrolysis === DNase agar is used to test whether a microbe can produce the exoenzyme deoxyribonuclease (DNase), which hydrolyzes DNA. Methyl green is used as an indicator in the growth medium because it is a cation that provides an opaqueness to a medium with the presence of negatively charged DNA strands. When DNA is cleaved, the media becomes clear, showing the presence of DNase activity. DNA hydrolysis is tested by growing an organism on a DNase Test Agar plate (providing nutrients and DNA) and then checking the plate for hydrolysis. The agar plate has DNA-methyl green complex, and if the organism on the agar does hydrolyze DNA then the green color fades and the colony is surrounded by a colorless zone.
== History == The term "food drunk" has sometimes been used to describe the supposed state of a person after overeating. In October 1905, Thomas Edison (then 58 years old) declared that "the country is food drunk.... the people eat too much and sleep too much, and don't work enough". The phrase was echoed by Dr J E Rullfson of Toledo after fasting for sixty days from January 5, 1907. He held that the entire human race is food drunk, saying "the dinner eaten by Napoleon just before the Battle of Leipzig proved so indigestible that the monarch's brain was clouded and as a result the battle was lost and a pie which King Philip failed to digest caused the revolt of the Netherlands."
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.