Methionine oxidation raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-12-19 and is reviewed periodically as new material appears.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
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.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | ≥ 95 % of peak area by HPLC | Some suppliers quote 98 % or higher |
| Identity confirmation | Mass spectrometry (electrospray or MALDI) | Observed mass is compared with the calculated mass |
| Common analytical method | Reversed-phase HPLC on a C18 column | Acetonitrile and water gradients with trifluoroacetic acid |
| Primary degradation route | Oxidation of the methionine residue | Yields a sulfoxide that separates cleanly on chromatography |
| Storage of dissolved material | Aliquoted and frozen at −20 °C or below | Single-use aliquots avoid repeated temperature cycling |
Solid material is normally kept at minus 20 degrees Celsius in a sealed, desiccated container. Reconstituted solutions are less stable and are usually divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of activity. Light exposure is minimized by using amber glassware or foil wrapping. Published stability data for this peptide are sparse, so recommended storage conditions rest mainly on general practice for short synthetic peptides rather than on dedicated study.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
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 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.
tracer A molecule or a specific atom within a molecule that has been chemically or radioactively labelled so that it can be easily tracked or followed through a biochemical process or located in a cell or tissue.
=== Physical features === LS is recognized as being part of a spectrum of conditions that affect the Hypothalamic–pituitary–somatotropic axis and cause significant derangements in human growth, development, and metabolism. Along this spectrum of conditions, individuals with LS and growth hormone deficiency display short stature, while individuals with acromegaly and gigantism result in the opposite phenotype of tall stature. In addition to short stature, other characteristic physical symptoms of LS include: prominent forehead, depressed nasal bridge, underdevelopment of mandible, truncal obesity, and micropenis in males. Left untreated, the average height attained by individuals with LS are approximately 4–4.5 feet (1.2–1.4 m) in women/men respectively. Additional physical features include delayed bone age, hypogonadism, blue sclera, high-pitched voice, acrohypoplasia, sparse hair growth, and crowded teeth. The breasts of females reach normal size, and in some are large in relation to body size. It has been suggested that hyperprolactinemia may contribute to the enlarged breast size. Seizures are frequently seen secondary to hypoglycemia. Some genetic variations decrease intellectual capacity. Laron syndrome patients also do not develop acne, except temporarily during treatment with IGF-1 (if performed).
They inhabited sparsely populated areas in the Dnieper, Don, Terek, and Ural river basins, and played an important role in the historical development of mounted horsemanship and cavalry battle tactics, and cultural development of both Ukraine and parts of Russia. The Cossack way of life, centered strongly in their union and dependence on horses, persisted via both direct descendants and acquired ideals in other nations into the twentieth century, though the sweeping societal changes of the Russian Revolution disrupted Cossack society as much as any other part of Russia; many Cossacks migrated to other parts of Europe following the establishment of the Soviet Union, while others remained and assimilated into the Communist state. Cohesive Cossack-based cavalry units were organized and many fought for both Nazi Germany and the Soviet Union during World War II. After World War II, the Soviet Union disbanded the Cossack units within the Soviet Army, leading to the suppression of many Cossack traditions during the rule of Joseph Stalin and his successors. However, during the Perestroika era in the late 1980s, descendants of Cossacks began to revive their horse-centered way of life and historic traditions. In 1988, the Soviet Union enacted a law permitting the re-establishment of former Cossack hosts and the formation of new ones. Throughout the 1990s, numerous regional authorities consented to delegate certain local administrative and policing responsibilities to these reconstituted Cossack hosts.
Sources: en.wikipedia.org
=== Aortic regurgitation === Aortic regurgitation is treated with aortic valve replacement, which is recommended in patients with symptomatic severe aortic regurgitation. Aortic valve replacement is also recommended in patients that are asymptomatic but have chronic severe aortic regurgitation and left ventricular ejection fraction of less than 50%. Hypertension is treated in patients with chronic aortic regurgitation, with the anti-hypersensives of choice being calcium channel blockers, ACE inhibitors, or ARBs. Also, endocarditis prophylaxis is indicated before dental, gastrointestinal or genitourinary procedures. Mild to moderate aortic regurgitation should be followed with echocardiography and a cardiac stress test once every 1–2 years. In severe moderate/severe cases, patients should be followed with echocardiography and cardiac stress test and/or isotope perfusion imaging every 3–6 months.
It can do this by abstracting a proton with its basic nitrogen to make a positively charged intermediate and then use another molecule, a buffer, to extract the proton from its acidic nitrogen. In carbonic anhydrases, a histidine proton shuttle is utilized to rapidly shuttle protons away from a zinc-bound water molecule to quickly regenerate the active form of the enzyme. In helices E and F of hemoglobin, histidine influences binding of dioxygen as well as carbon monoxide. This interaction enhances the affinity of Fe(II) for O2 but destabilizes the binding of CO, which binds only 200 times stronger in hemoglobin, compared to 20,000 times stronger in free heme. The tautomerism and acid-base properties of the imidazole side chain has been characterized by 15N NMR spectroscopy. The two 15N chemical shifts are similar (about 200 ppm, relative to nitric acid on the sigma scale, on which increased shielding corresponds to increased chemical shift). NMR spectral measurements shows that the chemical shift of N1-H drops slightly, whereas the chemical shift of N3-H drops considerably (about 190 vs. 145 ppm). This change indicates that the N1-H tautomer is preferred, possibly due to hydrogen bonding to the neighboring ammonium. The shielding at N3 is substantially reduced due to the second-order paramagnetic effect, which involves a symmetry-allowed interaction between the nitrogen lone pair and the excited π* states of the aromatic ring. At pH > 9, the chemical shifts of N1 and N3 are approximately 185 and 170 ppm.
The 2-aza-β-tyrosine subunit of kedarcidin chromophore is altogether unknown in any other natural product; this lack of precedence frustrates any attempt at a priori identification of the genes responsible for synthesizing this structure. However, six genes are conserved among the biosynthetic clusters of kedarcidin, C-1027, and maduropeptin—while these later two enediynes do not contain a 2-aza-β-tyrosine subunit, they do feature similar (L)-tyrosine-derived components, leading Shen et al. to propose a pathway for the synthesis of the corresponding kedarcidin subunit beginning with 2-aza-L-tyrosine. This α-amino acid is thus believed to be converted to the corresponding β-amino acid by KedY4, an aminomutase encoded in the ked cluster. The resulting product is believed to be loaded onto the peptidyl carrier protein KedY2 and subsequently chlorinated by KedY3, an flavin adenine dinucleotide-dependent halogenase.
In November 2025, federal prosecutors in Washington, D.C., opened a criminal investigation into Jerome H. Powell, the Chair of the Federal Reserve, concerning the renovation of the Federal Reserve’s headquarters and whether Powell made false or misleading statements to Congress about the scope and cost of the project. The inquiry, approved by U.S. Attorney Jeanine Pirro, involves a review of Powell’s congressional testimony and an examination of internal spending and planning records related to the renovation. The investigation marks a significant escalation in the long-running conflict between President Donald Trump and Powell, whom Trump has repeatedly criticized for resisting pressure to sharply cut interest rates. Trump has publicly accused Powell of “incompetence,” threatened to remove him from office, and raised the prospect of legal action tied to the renovation project. As of April 2026, Powell has not been charged with any crime. The Department of Justice dropped the investigation on April 24, 2026.
Sources: en.wikipedia.org
== Chemistry == Levobunolol is the pure L-enantiomer of bunolol and has more than 60 times the pharmacological activity of D-bunolol. It is used as the hydrochloride, which melts at 209 to 211 °C (408 to 412 °F) and is soluble in water and methanol and slightly soluble in ethanol.
==== Women's international friendly matches ==== 22 February – China 0–0 Ireland. 8 April – USA 2–0 Ireland. 11 April – USA 1–0 Ireland. 22 June – Ireland 3–2 Zambia. 6 July – Ireland 0–3 France. 14 July – A friendly pre-World Cup warmup match against Colombia in Brisbane was abandoned after 20 minutes following harsh incidents by the South Americans against Denise O'Sullivan and Ruesha Littlejohn which earned the offenders yellow cards. O'Sullivan went to hospital with an injury inflicted by Colombian Daniela Caracas who said after the match that the Irish players "are little girls" ("Son unas nenas"), and "let them eat shit" ("que coman mierda").
For copper, the CTAP-1 sensor shows a response in the UV region when Cu(I) binds to an azatetrathiacrown motif that in turn excites a pyrazoline-based dye that is attached. In Coppersensor-1 (CS1), a thioether-rich motif binds to Cu(I) causing the excitation of a boron-dipyrromethene (BODIPY) dye in the visible region. Iron sensors include Pryrene-TEMPO, in which the binding of iron to TEMPO quenches the fluorescence of pyrene when no Fe(II) is bound. Upon binding however, TEMPO is reduced and pyrene regains fluorescence. This probe is limited in that an analogous response can be generated by unwanted free radicals, and that it can only by used in acidic solution. The DansSQ Fe(II)-binding system consists of a Dansyl group bound to styrylquinoline and operates by the disruption of intra-molecular charge transfer. It is limited in that it is only soluble in acetonitrile in 10% H2O. Cobalt sensors have been made that capitalize on the breaking of C-O bonds by Co(II) in a fluorescent probe known as Cobalt Probe 1 (CP1).
Sources: en.wikipedia.org
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.
The methionine residue at the start of the chain is vulnerable to oxidation, producing a sulfoxide variant. Amide bonds can also hydrolyze, though more slowly under neutral conditions. Cold storage, oxygen exclusion and minimization of freeze-thaw cycles slow both processes but do not stop them.
A purity number on a certificate does not establish that a powder is the same product as a registered nasal medicine. Counter-ion content, residual solvents and peptide-related impurities may differ between the two. Independent verification is the only way to narrow that gap.
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.