The short version of methionine sulfoxide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-09. Anything still debated is marked as such rather than presented as settled.
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide (ACTH fragment analog) | Not a steroid; does not belong to the melanocortin agonist drugs by marketing category |
| Molecular formula | C37H51N9O10S (commonly cited) | Reported values vary slightly with salt and counter-ion content |
| Appearance | White to off-white lyophilized powder | A single batch may appear as a loose cake or fluffy solid |
| Solubility | Freely soluble in water and aqueous buffer | Stock solutions are usually prepared in sterile water or saline |
| Typical storage | −20 °C or below, desiccated and protected from light | Seal opened vials promptly to limit moisture uptake |
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
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.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
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.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
== Early life and education == Bibudhendra Sarkar was born on August 2, 1935, in Kushtia, Bengal, British India (now Bangladesh). His father, Surendra Nath Sarkar, was a lawyer, and his mother, Sucheta Sarkar (née Chaki), a homemaker, died when he was one year old. He completed his kindergarten and primary education at Kushtia Mission School, a Catholic institution. Following the Partition of India in 1947, Sarkar's family relocated to Calcutta after losing their possessions. He attended City College School and later City College, Kolkata, earning his Matriculation and Intermediate Science certifications from the University of Calcutta. He pursued higher education at Banaras Hindu University in Uttar Pradesh, specializing in the chemistry of natural products and earning Bachelor of Pharmacy (B.Pharm) and Master of Pharmacy (M.Pharm) degrees. During his undergraduate studies, Sarkar worked as a summer researcher at the Central Drug Research Institute in Lucknow, under the mentorship of Manojit Mohan Dhar, who encouraged him to pursue graduate studies abroad. He subsequently moved to the United States, completing a PhD in biochemistry at the University of Southern California in 1964 under the supervision of Paul Saltman. At USC, his work was influenced by chemists Sydney Benson (chemical kinetics), Arthur Adamson (physical chemistry), and Bo Malmström (metal-activated enzyme chemistry).
In about 5–10% of cases, the nodes will calcify circumferentially, producing so-called "eggshell" calcification. This finding, however, is not exclusively diagnostic of silicosis. In some cases, the pulmonary nodules may also become calcified. A computed tomography or CT scan can also provide a mode detailed analysis of the lungs, and can reveal cavitation due to concomitant mycobacterial infection.
Microscopically, each liver lobe is seen to be made up of hepatic lobules. The lobules are roughly hexagonal, and consist of plates of hepatocytes, and sinusoids radiating from a central vein towards an imaginary perimeter of interlobular portal triads. The central vein joins to the hepatic vein to carry blood out from the liver. A distinctive component of a lobule is the portal triad, which can be found running along each of the lobule's corners. The portal triad consists of the hepatic artery, the portal vein, and the common bile duct. The triad may be seen on a liver ultrasound, as a Mickey Mouse sign with the portal vein as the head, and the hepatic artery, and the common bile duct as the ears. Histology, the study of microscopic anatomy, shows two major types of liver cells: parenchymal cells and nonparenchymal cells. About 70–85% of the liver volume is occupied by parenchymal hepatocytes. Nonparenchymal cells constitute 40% of the total number of liver cells but only 6.5% of its volume. The liver sinusoids are lined with two types of cell, sinusoidal endothelial cells, and phagocytic Kupffer cells. Hepatic stellate cells are nonparenchymal cells found in the perisinusoidal space, between a sinusoid and a hepatocyte. Additionally, intrahepatic lymphocytes are often present in the sinusoidal lumen.
== Career == Somogyi was born on March 7, 1883, in the village of Zsámánd in Hungary (today Reinersdorf, part of Heiligenbrunn, Austria). He graduated in chemical engineering from the University of Budapest in 1905. After an additional year as an assistant in biochemistry, Somogyi went to the United States, where he eventually found a position as an assistant in biochemistry at Cornell University (1906–1908). He returned to Budapest where he worked at the Municipal Laboratory for the next decade. In 1914, he received his Ph.D. from the University of Budapest, submitting a dissertation on catalytic hydrogenation. During World War I he was in charge of providing food to the destitute. Somogyi was invited to return to the United States by Philip A. Shaffer, whom he had known at Cornell. In 1922 Somogyi became an instructor in biochemistry at Washington University School of Medicine. There Somogyi worked with Shaffer and Edward Adelbert Doisy on insulin preparation and insulin's use in the treatment of diabetes. In 1926, Somogyi became the first biochemist on the staff of the new Jewish Hospital of St. Louis where he worked closely with physicians. He directed the hospital's clinical laboratory until he retired in 1957.
Brigade Infantry: 1st Battalion (Airborne), 505th Infantry 2nd Battalion (Airborne), 505th Infantry 1st Battalion (Airborne), 508th Infantry Brigade Artillery: 2nd Battalion (Airborne), 321st Artillery (105mm) Brigade Aviation: Company A, 82nd Aviation Battalion Brigade Reconnaissance: Troop B, 1st Squadron (Armored), 17th Cavalry Company O (Ranger), 75th Infantry Brigade Support: 82nd Support Battalion 58th Signal Company Company C, 307th Engineer Battalion (Airborne) 408th Army Security Agency Detachment 52nd Chemical Detachment 518th Military Intelligence Detachment 307th Medical (Airborne) Headquarters and Alpha Company The deployment of the 3rd Brigade took place with significant problems and controversy. In The Rise and Fall of an American Army: US Ground Forces in Vietnam, 1965–1973, author Shelby L. Stanton describes how, other than the 82nd, only two under-strength Marine and four skeletonized Army divisions were left stateside by the beginning of 1968. The U.S. Military Assistance Command, Vietnam (MACV), desperate for additional manpower, wanted the division to deploy to Vietnam, and the Department of the Army, wishing to retain its "sole readily deployable strategic reserve, the last real vestige of actual Army divisional combat potency in the United States left to the Pentagon," compromised by sending the 3d Brigade. As Stanton wrote:
Sources: en.wikipedia.org
Small amounts of organoselenium compounds have been used to modify the catalysts used for the vulcanization for the production of rubber. Selenium is used in some anti-dandruff shampoos in the form of selenium disulfide such as Selsun and Vichy Dereos brands.
== See also == Drug design Drug repositioning Pharmaceutical engineering Pharmaceutical manufacturing Generic drug International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use, a consensus between the U.S. Food and Drug Administration (FDA), EU, and Japan. Lists of investigational drugs List of pharmaceutical companies
=== Microelectronics === The accurate and damage-free surface ion milling provides makes it perfect for the precise fabrication of semiconductors. Using ion milling for microelectronics can create well-defined features and patterns on semiconductor wafers.
== Side effects == The effects of local skin reactions with clascoterone were similar to placebo in two large phase III randomized controlled trials. Suppression of the hypothalamic–pituitary–adrenal axis (HPA axis) may occur during clascoterone therapy in some individuals due to its cortexolone metabolite. HPA axis suppression as measured by the cosyntropin stimulation test was observed to occur in 3 of 42 (7%) of adolescents and adults using clascoterone for acne. HPA axis function returned to normal within 4 weeks following discontinuation of clascoterone. Hyperkalemia (elevated potassium levels) occurred in 5% of clascoterone-treated individuals and 4% of placebo-treated individuals.
Sources: en.wikipedia.org
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.
It was developed in the Soviet Union during the early 1980s by groups at the Institute of Molecular Genetics in Moscow. Russian approval for intranasal use followed, and it has been marketed there since. Western laboratories encountered it mainly through translated literature and, later, through online research-chemical trade.
It holds a Russian registration as a prescription nasal product but has no approval from the European Medicines Agency or the United States Food and Drug Administration. Buyers outside Russia usually receive material sold strictly for laboratory research. That distinction matters because research-grade and pharmaceutical-grade products carry different documentation and testing expectations.
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.