This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-15. Anything still debated is marked as such rather than presented as settled.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
| Property | Value | Notes |
|---|---|---|
| Typical analytical method | Reversed-phase HPLC with UV detection | Separates target peptide from truncated and oxidised forms |
| Identity confirmation | LC-MS or ESI-MS | Compares observed and calculated molecular ion |
| Primary degradation route | Methionine oxidation | Forms the sulfoxide; monitored as an early-eluting peak |
| Short-term storage | 2 to 8 degrees Celsius | Applies to working vials and reconstituted portions |
| Common synonyms | ACTH(4–10) analogue, MEHFPGP | Descriptive names used in laboratory catalogues |
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
Claims about enhanced focus, memory, or mood in healthy people rest mostly on anecdotal reports and community discussion rather than on controlled data. It remains unclear whether any cognitive benefit observed in patients recovering from brain injury would extend to uninjured users. Dose-response relationships, long-term safety, and interactions with other drugs are not well characterized in the peer-reviewed literature. Questions about optimal route of administration and treatment duration likewise remain open.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
"Cooks in the early Navy were left to their own imaginations when it came to preparing meals. In the main, this resulted in whatever was on the official ration for that day of the week being tossed in a ship's coppers and boiled until meal time. The first official Navy cook book was produced by Paymaster F. T. Arms and published by the Bureau of Supplies and Accounts in 1902. It contained five recipes for soup, six for fish, thirty-four for meats, fowl, and eggs, and several for desserts, including "plum duff"."
==== Surreptitious insulin use ==== When individuals take insulin without needing it, to purposefully induce hypoglycemia, this is referred to as surreptitious insulin use or factitious hypoglycemia. Some people may use insulin to induce weight loss, whereas for others this may be due to malingering or factitious disorder, which is a psychiatric disorder. Inappropriate usage of insulin is most common in people who have had exposure to diabetes management, such as healthcare workers, people who have relatives with diabetes, or people with diabetes themselves. The classic way to identify surreptitious insulin use is through blood work revealing high insulin levels with low C-peptide and proinsulin.
=== Archaea === In 2022, the discovery of serotonin N-acetyltransferase (SNAT)—the penultimate, rate-limiting enzyme in the melatonin biosynthetic pathway—in the archaeon Thermoplasma volcanium firmly places melatonin biosynthesis in all three major domains of life, dating back to ~4 Gya.
==== Estrogens (estrogen receptor agonists) ==== Conjugated estrogens (conjugated equine estrogens; CEEs; Premarin) – estrogen (estrogen receptor agonist) – atrophic vaginitis, dyspareunia [132] Conjugated estrogens oral (Enjuvia; synthetic conjugated estrogens) – estrogen (estrogen receptor agonists) – atrophic vaginitis [133] Conjugated estrogens/bazedoxifene (Aprela; bazedoxifene acetate/conjugated estrogens; bazedoxifene/conjugated estrogens; bazedoxifene/Premarin; BZA/CE; CE/BZA; conjugated estrogens/bazedoxifene acetate; Duavee; Duavive; Premarin/bazedoxifene; SERM + Premarin) – combination of conjugated estrogens (estrogen) and bazedoxifene (selective estrogen receptor modulator (SERM)) – atrophic vaginitis [134] Estradiol (Estrofem; Innofem; oral estradiol; Vagifem; vaginal estradiol) – estrogen (estrogen receptor agonist) – atrophic vaginitis [135] Estradiol transdermal micro patch (Estradot; Minivelle; Vivelle-Dot) – estrogen (estrogen receptor agonist) – atrophic vaginitis [136] Estradiol vaginal (E2; 17β-estradiol; Estradiol VagiCap; Imvexxy; Joyesta; TX-12-004-HR; TX-004HR; VagiCap; Yuvvexy) – estrogen (estrogen receptor agonist) – atrophic vaginitis [137] Estradiol acetate (Estrace; estradiol acetate intravaginal ring; estradiol acetate IVR; Femring; Menoring) – estrogen (estrogen receptor agonist) – atrophic vaginitis [138] Estriol succinate vaginal gel (6α-hydroxyestradiol; Blissel; Gelistrol) – estrogen (estrogen receptor agonist) – atrophic vaginitis [139] Estriol/lactobacillus (estriol-Lactobcillus acidophilus mixt.; estriol/lyophilised lactobacilli; Gynoflor; ultra-low dose estrogen/lactobacillus) – combination of estriol (estrogen) and lactobacillus (probiotic) – atrophic vaginitis [140] Ospemifene (FC-1271a; Ophena; Osphena; Senshio) – selective estrogen receptor modulator (SERM) – atrophic vaginitis, dyspareunia [141]
Sources: en.wikipedia.org
Potential fields of BSG application include ultra-sensitive detectors, high-performance catalytic cells, nanochannels for DNA sequencing and manipulation, high-performance heat sinking surfaces, rechargeable batteries of enhanced performance, nanomechanical resonators, electron multiplication channels in emission Nano-electronic devices, high-capacity sorbents for safe hydrogen storage. Three dimensional bilayer graphene has also been reported.
=== Measurement methods === Traditional CRP measurement only detected CRP in the range of 10 to 1,000 mg/L, whereas high sensitivity CRP (hs-CRP) detects CRP in the range of 0.5 to 10 mg/L. hs-CRP can detect cardiovascular disease risk when in excess of 3 mg/L, whereas below 1 mg/L would be low risk. Traditional CRP measurement is faster and less costly than hs-CRP, and can be adequate for some applications, such as monitoring hemodialysis patients. Current immunoassay methods for CRP have similar precision to hsCRP performed by nephelometry and could probably replace hsCRP for cardiovascular risk assessment, however, in the United States this would represent off-label use, making it a laboratory-developed test under FDA regulations.
== Role in microbial cooperation == Once pyoverdine is secreted, it diffuses freely in the environment. Iron-bound pyoverdine (also known as ferripyoverdine) can be taken up by any bacterial cell with the appropriate receptor, although this varies between strains. Importantly, this creates a common good which can be exploited by 'cheaters' which retain the ability to use pyoverdine but have stopped making it. Since pyoverdine production is energetically costly, this can create a fitness advantage in cells that are not synthesizing it. Consequently, pyoverdine has become a model trait to study microbial cooperation and exploitation. In P. aeruginosa, pyoverdine non-producing "cheat" bacteria have been shown to i) evolve readily from a producing ancestor; and ii) outcompete cooperating strains in mixed culture in a density- and frequency-dependent manner. Since pyoverdine usage relies on passive diffusion and pyoverdine production is metabolically costly, environmental conditions are known to influence the likelihood of successful exploitation. The competitive advantage of pyoverdine non-producers over producers in mixed culture was shown to be maximized when environments are well-mixed and molecules diffuse readily (low spatial structure) and when the costs and benefits of pyoverdine production are high, i.e. when iron is strongly limited. Most studies on pyoverdine cooperation and cheating have been conducted using clinical isolates, but siderophore exploitation was recently also demonstrated in natural Pseudomonas isolates from non-clinical samples.
Sources: en.wikipedia.org
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.
Oxidation of the methionine residue to the sulfoxide is a frequently reported change, and it usually appears as an earlier-eluting peak in reversed-phase chromatography. Backbone hydrolysis products can also accumulate in aqueous solution.
Liquid chromatography coupled with mass spectrometry is the usual approach, because the observed molecular ion can be compared with a calculated mass of about 813.9 Da. Retention time alone does not establish identity.
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.