This is a working overview of Selank, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-14 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
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.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Pesticides include a wide variety of chemical compounds, used in both agriculture and non-agricultural contexts. Globally, roughly 4,000 chemical compounds are officially registered as being designed for biological activity as pesticides. Pesticides are broadly categorized into plant protection products for countering pests and diseases, and biocidal products such as disinfectants, which may be used domestically to control harmful organisms. Agricultural pesticides are further grouped into herbicides (used against plants), fungicides (used against fungi and spores), and insecticides (against insects). The properties targeted by pesticides are often shared by both the intended targets and other non-target species, including humans. Both those working with pesticides and those living near areas of application are at increased risk. Evidence from epidemiological, animal, and in vitro studies suggests that exposure to pesticides increases the risk for Parkinson's disease. Numerous meta‐analyses and epidemiological studies have reported an increased risk ratio or odds ratio for being exposed to pesticides. PD prevalence is associated with local pesticide use. Length of duration of pesticide exposure is associated with increased PD risk, while high proximity and frequent pesticide exposure are associated with earlier age of onset. Pesticide exposure after diagnosis may accelerate disease progression. Herbicides such as paraquat, diquat, rotenone and glyphosate are the most clearly established environmental toxicants for PD and are likely causal.
==== Mexico's economy ==== Over the past few decades, drug cartels have become integrated into Mexico's economy. Approximately 500 cities are directly engaged in drug trafficking and nearly 450,000 people are employed by drug cartels. Additionally, the livelihood of 3.2 million people is dependent on the drug cartels. Between local and international sales, such as to Europe and the United States, drug cartels in Mexico see a $25–30 bn yearly profit, a great deal of which circulates through international banks such as HSBC. Drug cartels are fundamental in local economics. A percentage of the profits seen from the trade are invested in the local community. Such profits contribute to the education and healthcare of the community. While these cartels bring violence and hazards into communities, they create jobs and provide income for its many members.
This is about 17% of the terrestrial ratio of 156 deuterium atoms per million hydrogen atoms. Comets such as Comet Hale–Bopp and Halley's Comet have been measured to contain more deuterium (about 200 atoms per million hydrogens), ratios which are enriched with respect to the presumed protosolar nebula ratio, probably due to heating, and which are similar to the ratios found in Earth seawater. The recent measurement of deuterium amounts of 161 atoms per million hydrogen in Comet 103P/Hartley (a former Kuiper belt object), a ratio almost exactly that in Earth's oceans (155.76 ± 0.1, but in fact from 153 to 156 ppm), emphasizes the theory that Earth's surface water may be largely from comets. Most recently the 2H1HR of 67P/Churyumov–Gerasimenko as measured by Rosetta is about three times that of Earth water. This has caused renewed interest in suggestions that Earth's water may be partly of asteroidal origin. Deuterium has also been observed to be concentrated over the mean solar abundance in other terrestrial planets, in particular Mars and Venus.
Sources: en.wikipedia.org
=== Later history === In the 1960s, virologist and cancer researcher Chester M. Southam injected HeLa cancer cells into patients at the Jewish Chronic Disease Hospital. When three doctors resigned after refusing to inject patients without their consent, the experiment gained considerable media attention. The NIH was a major source of funding for Southam's research and required all research involving human subjects to obtain their consent before any experimentation. Upon investigating all of their grantee institutions, the NIH discovered that the majority of them did not protect the rights of human subjects. From then on, the NIH has required all grantee institutions to approve any research proposals involving human experimentation with review boards. In 1967, the Division of Regional Medical Programs was created to administer grants for research for heart disease, cancer, and strokes. That same year, the NIH director lobbied the White House for increased federal funding to increase research and the speed with which health benefits could be brought to the people. An advisory committee was formed to oversee the further development of the NIH and its research programs. By 1971, cancer research was in full force, and President Nixon signed the National Cancer Act, initiating a National Cancer Program, President's Cancer Panel, National Cancer Advisory Board, and 15 new research, training, and demonstration centers. Funding for the NIH has often been a source of contention in the US Congress, serving as a proxy for the political currents of the time.
=== mzAPI === Instead of defining new file formats or writing converters for proprietary vendor formats, a group of scientists proposed a common application program interface to shift the burden of standards compliance to the instruments manufacturers' existing data-access libraries.
Before 1830, few Americans used ice to refrigerate foods due to a lack of ice-storehouses and iceboxes. As these two things became more widely available, individuals used axes and saws to harvest ice for their storehouses. This method proved to be difficult, dangerous, and certainly did not resemble anything that could be duplicated on a commercial scale. Despite the difficulties of harvesting ice, Frederic Tudor thought that he could capitalize on this new commodity by harvesting ice in New England and shipping it to the Caribbean islands as well as the southern states. In the beginning, Tudor lost thousands of dollars, but eventually turned a profit as he constructed icehouses in Charleston, Virginia and in the Cuban port town of Havana. These icehouses as well as better insulated ships helped reduce ice wastage from 66% to 8%. This efficiency gain influenced Tudor to expand his ice market to other towns with icehouses such as New Orleans and Savannah. This ice market further expanded as harvesting ice became faster and cheaper after one of Tudor's suppliers, Nathaniel Wyeth, invented a horse-drawn ice cutter in 1825. This invention as well as Tudor's success inspired others to get involved in the ice trade and the ice industry grew. Ice became a mass-market commodity by the early 1830s with the price of ice dropping from six cents per pound to a half cent per pound. In New York City, ice consumption increased from 12,000 tons in 1843 to 100,000 tons in 1856. Boston's consumption leapt from 6,000 tons to 85,000 tons during that same period.
Amphetamine has a very similar structure and function to the endogenous trace amines, which are naturally occurring neuromodulator molecules produced in the human body and brain. Among this group, the most closely related compounds are phenethylamine, the parent compound of amphetamine, and N-methylphenethylamine, a structural isomer of amphetamine (i.e., it has an identical molecular formula). In humans, phenethylamine is produced directly from L-phenylalanine by the aromatic amino acid decarboxylase (AADC) enzyme, which converts L-DOPA into dopamine as well. In turn, N-methylphenethylamine is metabolized from phenethylamine by phenylethanolamine N-methyltransferase, the same enzyme that metabolizes norepinephrine into epinephrine. Like amphetamine, both phenethylamine and N-methylphenethylamine regulate monoamine neurotransmission via TAAR1; unlike amphetamine, both of these substances are broken down by monoamine oxidase B, and therefore have a shorter half-life than amphetamine.
Sources: en.wikipedia.org
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.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
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.