heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Analog of an ACTH fragment |
| Amino acid length | Seven residues | Met-Glu-His-Phe-Pro-Gly-Pro |
| Origin | Moscow, 1980s | Institute of Molecular Genetics |
| Approved regions | Russia and some neighboring states | Not cleared in Western markets |
| Common trade names | Multiple national brands | Sold as a nasal formulation |
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
Tofu (Japanese: 豆腐, Hepburn: Tōfu; Chinese: 豆腐; pinyin: dòufu; Korean: 두부; RR: dubu) or bean curd is a food prepared by pressing the curds of coagulated soy milk into solid white blocks of varying softness: 'silken', 'soft', 'firm', and 'extra (or super) firm'. It originated in China and has been consumed for over 2,000 years. Tofu is a traditional component of many East Asian and Southeast Asian cuisines; in modern Western cooking, it is commonly used as a meat substitute. Nutritionally, tofu is low in calories, while providing a rich source of protein. Cultivation of soybeans has one of the lowest needs for land use (1.3 m2/ 1000 kcal) and emits some of the lowest amounts of greenhouse gas emissions per gram of edible protein of any food (1.6 kg CO2/ 100 g protein).
== Relevance to the origin of life == The Miller–Urey experiment was proof that the building blocks of life could be synthesized abiotically from gases, and introduced a new prebiotic chemistry framework through which to study the origin of life. Simulations of protein sequences present in the last universal common ancestor (LUCA), or the last shared ancestor of all extant species today, show an enrichment in simple amino acids that were available in the prebiotic environment according to Miller–Urey chemistry. This suggests that the genetic code from which all life evolved was rooted in a smaller suite of amino acids than those used today. Thus, while creationist arguments focus on the fact that Miller–Urey experiments have not generated all 22 genetically-encoded amino acids, this does not actually conflict with the evolutionary perspective on the origin of life.
The Nobel Prize committee in 1923 credited the practical extraction of insulin to a team at the University of Toronto and awarded the Nobel Prize to two men: Frederick Banting and John Macleod. They were awarded the Nobel Prize in Physiology or Medicine in 1923 for the discovery of insulin. Banting, incensed that Best was not mentioned, shared his prize with him, and Macleod immediately shared his with James Collip. The patent for insulin was sold to the University of Toronto for one dollar. Two other Nobel Prizes have been awarded for work on insulin. British molecular biologist Frederick Sanger, who determined the primary structure of insulin in 1955, was awarded the 1958 Nobel Prize in Chemistry. Rosalyn Sussman Yalow received the 1977 Nobel Prize in Medicine for the development of the radioimmunoassay for insulin. Several Nobel Prizes also have an indirect connection with insulin. George Minot, co-recipient of the 1934 Nobel Prize for the development of the first effective treatment for pernicious anemia, had diabetes. William Castle observed that the 1921 discovery of insulin, arriving in time to keep Minot alive, was therefore also responsible for the discovery of a cure for pernicious anemia. Dorothy Hodgkin was awarded a Nobel Prize in Chemistry in 1964 for the development of crystallography, the technique she used for deciphering the complete molecular structure of insulin in 1969.
Sources: en.wikipedia.org
=== Humans === The cycling of and excretion of urea by the kidneys is a vital part of mammalian metabolism. Besides its role as carrier of waste nitrogen, urea also plays a role in the countercurrent exchange system of the nephrons, that allows for reabsorption of water and critical ions from the excreted urine. Urea is reabsorbed in the inner medullary collecting ducts of the nephrons, thus raising the osmolarity in the medullary interstitium surrounding the thin descending limb of the loop of Henle, which makes the water reabsorb. By action of the urea transporter 2, some of this reabsorbed urea eventually flows back into the thin descending limb of the tubule, through the collecting ducts, and into the excreted urine. The body uses this mechanism, which is controlled by the antidiuretic hormone, to create hyperosmotic urine — i.e., urine with a higher concentration of dissolved substances than the blood plasma. This mechanism is important to prevent the loss of water, maintain blood pressure, and maintain a suitable concentration of sodium ions in the blood plasma. The equivalent nitrogen content (in grams) of urea (in mmol) can be estimated by the conversion factor 0.028 g/mmol. Furthermore, 1 gram of nitrogen is roughly equivalent to 6.25 grams of protein, and 1 gram of protein is roughly equivalent to 5 grams of muscle tissue. In situations such as muscle wasting, 1 mmol of excessive urea in the urine (as measured by urine volume in litres multiplied by urea concentration in mmol/L) roughly corresponds to a muscle loss of 0.67 grams.
=== Affinity-based proteome analysis tools === The definition of TDP includes a requirement to identify the "protein", either as a distinct proteoform or ORF product. While this is most typically achieved using a mass spectrometer to fragment ions, from either intact proteoforms or peptides of resolved proteoforms, it is also possible to identify and quantify canonical "proteins" using affinity-based reagents, such as O-link and SomaScan which use antibodies or aptamers, respectively. The generic term "protein" is used here because it is unclear whether these reagents identify certain proteoforms or a variety of proteoforms from the same ORF product. These methods thus produce similar, yet different, information relative to each other and to proteogenomic BUP approaches using LC/MS/MS. Because of the claimed (i) "depth" of these assays in terms of identifying canonical protein sequences; and (ii) apparent ability to quantify changes in the abundance of those proteins in samples that can be problematic for other proteomics technologies (e.g. plasma and serum), these technologies have become popular in studies having enormous sample numbers that are impossible to directly address by other proteomics technologies. However, the substantial lack of correlation between these technologies, as well as with other established proteomics technologies, needs to be addressed, along with fully characterizing the exact proteoforms that these reagents are identifying. This will thus also require transparent verification of the quality and selectivity of any antibodies and aptamers used.
Recent studies have shown the presence of microplastics in breast milk, often leading to exposures in very young children. While it has already been established that chemicals such as flame retardants and pesticides have been detected in breast milk, knowledge about microplastics is limited in comparison. A 2022 study detected microplastics in 26 of 34 breast milk samples, with particles ranging from 2 to 12μm in size, raising concerns about infant exposure during critical developmental windows. No safe or harmful exposure level for microplastics has been established, and exposure to MNPs during early developmental stages has raised questions about possible developmental effects or other health issues later in life. Additionally, breast pumps and breastmilk storage bags are frequently made of plastic. Freezing liquid in a plastic container and then heating it up (the "freeze-thaw cycle") has been shown to increase the presence of microplastics. Similar results have been seen from heating plastic reusable food containers in a microwave, showing the increased release of MNPs. It is not recommended that frozen breastmilk ever be thawed in a microwave.
Sources: en.wikipedia.org
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.
It is registered as a medicine in Russia and has been used clinically there for decades. No regulatory agency in Western Europe or North America has approved it for any indication.
Semax corresponds to the four-to-ten fragment of adrenocorticotropic hormone. Because it omits the first three residues, it lacks the adrenal-stimulating action of the full hormone.
Registered medical products are most often 0.1% nasal drops. Research suppliers ship lyophilized powder, usually in milligram quantities, which is dissolved before use. The active peptide is the same in both cases; presentation and excipients differ.