A practical reference on TKPRPGP: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-05. Anything still debated is marked as such rather than presented as settled.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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 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.
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.
== Sensitivity == It has been shown that PMCA is capable of detecting as little as a single molecule of oligomeric infectious PrPSc. PMCA possesses the ability to generate millions infectious units, starting with the equivalent to one PrPSc oligomer; well below the infectivity threshold. This data demonstrates that PMCA has a similar power of amplification as PCR techniques used to amplify DNA. It opens a great promise for development of a highly sensitive detection of PrPSc, and for understanding the molecular basis of prion replication. Indeed, PMCA has been used by various groups to detect PrPSc in blood of animals experimentally infected with prions during both the symptomatic and pre-symptomatic phases as well as in urine.
== Advertising == Sonic ran its first television advertisement in 1977. One of the company's most memorable advertising campaigns, which ran from 1987 to 1993, featured Frankie Avalon. In May 1999, the company began a new campaign featuring the character Katie the Carhop. Sonic was also involved with NASCAR. The company contracted with Richard Childress Racing in late 2000 to be an associate sponsor for Dale Earnhardt Sr. during the 2001 NASCAR Winston Cup Series season. After Earnhardt died in an accident at the 2001 Daytona 500, the company continued its sponsorship with his replacement driver Kevin Harvick, through the end of the 2003 season. Sonic returned to NASCAR several years later to sponsor Sam Hornish Jr. and Richard Petty Motorsports in 2015. In 2004, the company became more widely known nationally by advertising in television markets hundreds of miles from its nearest franchise. Improvisational actors T. J. Jagodowski and Peter Grosz became known to American television viewers from their "Two Guys" series of commercials. Similar series of ads for the company have featured other duos of improvisational performers, including Molly Erdman and Brian Huskey, Katie Rich and Sayjal Joshi, and Emily Wilson and Tim Baltz. In 2010, national auditions were held and a new series of commercials began airing, some of which featured carhops from Wisconsin and Austin, Texas. In 2012 the "Two Guys" returned to the company's television ads. In 2018 Sonic supplemented their "Two Guys" commercials with complementary "Two Gals" commercials.
The first pass through the hepatic portal vein results in some of the drug being metabolized by O-demethylation into an active metabolite of dextromethorphan called dextrorphan, the 3-hydroxy derivative of dextromethorphan. The therapeutic activity of dextromethorphan is believed to be caused by both the drug and this metabolite. Dextromethorphan also undergoes N-demethylation (to 3-methoxymorphinan or MEM), and partial conjugation with glucuronic acid and sulfate ions. Hours after dextromethorphan therapy, (in humans) the metabolites (+)-3-hydroxy-N-methylmorphinan and (+)-3-morphinan and traces of the unchanged drug are detectable in the urine. A major metabolic catalyst involved is the cytochrome P450 enzyme known as 2D6, or CYP2D6. A significant portion of the population has a functional deficiency in this enzyme and are known as poor CYP2D6 metabolizers. O-demethylation of dextromethorphan to dextrorphan contributes to at least 80% of the dextrorphan formed during dextromethorphan metabolism. As CYP2D6 is a major metabolic pathway in the inactivation of dextromethorphan, the duration of action and effects of dextromethorphan can be increased by as much as three times in such poor metabolizers. In one study on 252 Americans, 84.3% were found to be "fast" (extensive) metabolizers, 6.8% to be "intermediate" metabolizers, and 8.8% were "slow" metabolizers of dextromethorphan. A number of alleles for CYP2D6 are known, including several completely inactive variants. The distribution of alleles is uneven amongst ethnic groups.
Announced tests: The athletes know when they are tested. Unannounced tests: Athletes don't know when they are tested. These tests are the effective ones when they are conducted outside of the competition periods.
Sources: en.wikipedia.org
The RCC's early economic policy has been characterized as being state capitalist in orientation. Many initiatives were established to aid entrepreneurs and develop a Libyan bourgeoisie. Seeking to expand cultivatable acreage, in September 1969 the government launched a "Green Revolution" to increase agricultural productivity and lessen Libyan reliance on imported food. They hoped to make Libya self-sufficient in food production. All land expropriated from Italian settlers or unused was repossessed and redistributed. Irrigation systems were established along the northern coastline and various inland oases. Production costs often surpassed produce value, keeping production in deficit and relying on state subsidies. With crude oil as the country's primary export, Gaddafi sought to improve Libya's oil sector. In October 1969, he proclaimed the current trade terms unfair, benefiting foreign corporations more than the Libyan state, and threatened to decrease production. In December, Jalloud successfully increased the price of Libyan oil. In 1970, other OPEC states followed suit, leading to a global increase in the price of crude oil. The RCC followed with the Tripoli Agreement of 1971, in which they secured income tax, back-payments and better pricing from the oil corporations; these measures brought Libya an estimated $1 billion in additional revenues in its first year. Increasing state control over the oil sector, the RCC began a program of nationalization, starting with the expropriation of British Petroleum's share of the British Petroleum-N.B.
=== La–Lem === Marc Lacroix (b. 1963). Belgian biochemist at the Institut Jules Bordet (Brussels), who specializes in breast cancer biology, metastasis and therapy. Keith Laidler (1916–2003). British-Canadian chemist and biochemist at the University of Ottawa. Expert on chemical and enzyme kinetics. Fellow of the Royal Society of Canada. Henry Lardy (1917–2010). American biochemist at the University of Wisconsin, noted for work on metabolism. Member Natl. Acad. Sci. USA. Michel Lazdunski (b. 1938). French biochemist and neuroscientist at Sophia Antipolis. Known especially for work on ion channels. Full Member of the French Academy of Sciences. Jack Legge (1917–1996). Australian biochemist known for his work on blood pigment metabolism and participation in mustard gas trials on Australian Defence Force volunteers during WW2. Albert L. Lehninger (1917–1986). American biochemist at the University of Wisconsin. He discovered, with Eugene P. Kennedy, that mitochondria are the site of oxidative phosphorylation in eukaryotes. Author of several influential texts, including The Mitochondrion, Bioenergetics and Biochemistry. Member Natl. Acad. Sci. USA. Luis Federico Leloir FRS (foreign associate) (1906–1987). Argentinian biochemist at the Fundación Instituto Campomar (Buenos Aires) who worked on sugar nucleotides, carbohydrate metabolism, and renal hypertension. Nobel Prize for Chemistry (1970). Rudi Lemberg FRS (1896–1975). German-Australian biochemist, director of the Kolling Institute of Medical Research from 1935 to 1972. Known for porphyrin research.
=== Dental non-specific stress indicators === Dental non-specific stress indicators are features found on teeth that reflect episodes of physiological stress experienced during childhood, particularly during the period of enamel formation. They are described as "non-specific" because, while they signal that a stress event occurred, they do not identify the exact cause, such as whether it resulted from malnutrition, illness, or infection. Enamel forms through a process called amelogenesis, carried out by specialized cells known as ameloblasts, which produce enamel in sequential layers. When these cells are affected by systemic stress, the enamel formation process can be interrupted or altered, resulting in visible developmental defects.
=== As NCCIH (2014–present) === In 2014, while Josephine Briggs was the director, the NCCAM was renamed the National Center for Complementary and Integrative Health (NCCIH). Briggs retired in October 2017. On August 29, 2018, the NCCIH announced Helene Langevin as the new director. She was previously the director of the Osher Center and professor-in-residence of medicine at Harvard Medical School. Her medical interests involve connective tissue. Langevin "believes that the stretching of connective tissue is how several CAM modalities 'work,' such as chiropractic, massage, and ... acupuncture". Langevin has been studying acupuncture since the 1990s. At the time of her appointment, Gorski expressed concern that the balance of power at NCCIH would "shift back towards pseudoscience" with a massive budget to fund the shift. Under Langevin, NCCIH adopted a "whole person health" research framework, investigating how different domains of health—physiology, psychology, and environment—interconnect across the continuum between health and illness. She co-led several trans-NIH initiatives, including the NIH HEAL Initiative on opioid addiction and pain management, and the funding of a Whole Person Reference Physiome and Coordination Center co-funded by 20 NIH Institutes, Centers, and Offices. The NCCIH budget grew to approximately $170 million annually under her leadership. Langevin retired from NCCIH on November 30, 2025, returning to the University of Vermont as director of research at the Osher Center for Integrative Health.
A nuclear isomer is a metastable state of an atomic nucleus in which one or more nucleons (protons or neutrons) occupy excited state levels (higher energy levels). "Metastable" describes nuclei whose excited states have half-lives of 10−9 seconds or longer, 100 to 1000 times longer than the half-lives of the excited nuclear states that decay with a "prompt" half-life (ordinarily on the order of 10−12 seconds). Some references recommend using a threshold of 5×10−9 seconds to distinguish the metastable half-life from the normal "prompt" gamma-emission half-life. The half-lives of a number of isomers are far longer than this and may be minutes, hours, or years. The most extreme example known is the 180m73Ta nuclear isomer, which survives so long (at least 2.9×1017 years) that it has never been observed to decay spontaneously, and occurs naturally as a primordial nuclide, though uncommonly at only 1/8000 of all tantalum. The second most stable isomer is 210m83Bi, which does not occur naturally; its half-life is 3.04×106 years to alpha decay. The half-life of a nuclear isomer can exceed that of the ground state of the same nuclide, as with the two above, as well as, for example, 186m75Re, 192m277Ir, 212m84Po, 242m95Am and multiple holmium isomers.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.