If you have been reading about methionine sulfoxide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-12-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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.
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.
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
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.
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.
=== Drugs === The anti-diabetic medication pioglitazone was shown in a mouse model of ALD to be effective at treating the metabolic effects of ALD, including metabolic failure and increased oxidative stress. Pioglitazone was also shown to prevent axonal degeneration and increase mitochondria levels, as well as stop the progression of locomotor decline in ALD model mice. Subsequently, the experimental drug leriglitazone has been developed as a more brain penetrant metabolite of pioglitazone. As of 2023, leriglitazone is in phase 2/3 clinical trials for adult and childhood cALD in the USA and the EU, and has completed a clinical trial for AMN.
=== rRNA === Ribosomes, the organelles where protein translation takes place, are made from rRNA and ribosomal proteins. Ribosomes may be the best and most abundant example of nucleic acid quaternary structure. The specifics of ribosome structure varies among different kingdoms and species, but all ribosomes are made of a large subunit and a small subunit. Different classes of organisms have ribosomal subunits of different characteristic sizes. The three dimensional association of ribosomal subunits is essential for ribosomal function. The small subunit binds first to mRNA and then the large subunit is recruited. In order for a polypeptide to be formed, proper association of the mRNA and both ribosome subunits must occur. At left, the secondary structure of rRNA in the peptidyl transferase center of the ribosome in yeast. The peptidyl transferase center is where the formation of the peptide bond is catalyzed during translation. At right, the three-dimensional structure of the peptidyltransferase center. The helical rRNA is associated with globular ribosomal proteins. Incoming codons arrive at the A site and move to the P site, where peptide bond formation is catalyzed. One specific three dimensional structure that is commonly observed in rRNA is the A-minor motif. There are four types of A-minor motifs, all of which include many unpaired adenosines. These lone adenosines extend from outward and allow RNA molecules to bind other nucleic acids in the minor groove.
Many of these will stealthily snatch small cubs right from under the sleeping mother. There is record of a golden eagle snatching a yearling cub. Once out of hibernation, mother bears may be able to fight off most potential predators. Even cougars will be displaced by an angry mother bear if they are discovered stalking the cubs. Flooding of dens after birth may also occasionally kill newborn cubs. Bear fatalities are mainly attributable to human activities. Seasonally, thousands of black bears are hunted legally across North America, and some are illegally poached or trapped unregulated. Auto collisions also may kill many black bears annually.
=== Starting material === PMCA was originally based on the normal prion protein (PrPC) from healthy brain tissue, which is expensive. The advent of recombinant proteins have lower the cost somewhat, but the steps required to obtain the pure protein are laborious. In 2011, it was found that simply putting a prion protein transgene into a cell line and then lysing the cell without purification is enough. This is expected to make PMCA much cheaper. The cell line does not need to be of a neuronal origin. PMCA is most easily performed with catalysts which are abundant even in healthy cells: a polyanion (single-stranded RNA or sulfated glycans) and a phospholipid. A cell lysate would provide both of these catalysts and most clumps of PrPSc contain catalyst polyanion molecules anyways. Synthetic versions of these catalysts such as poly(A) RNA and 1-palmitoyl-2-oleoylphosphatidylglycerol (POPG) also work for propagating PrPSc. Additional required materials include buffer salts and detergent.
Sources: en.wikipedia.org
These data show that the perchlorate and chlorate are stronger oxidizers in acidic conditions than in basic conditions. Gas phase measurements of heats of reaction (which allow computation of ΔfH°) of various chlorine oxides do follow the expected trend wherein Cl2O7 exhibits the largest endothermic value of ΔfH° (238.1 kJ/mol) while Cl2O exhibits the lowest endothermic value of ΔfH° (80.3 kJ/mol).
=== 30 October === RSF brigadier general and suspected war criminal Al-Fateh Abdullah Idris was arrested by the RSF for filming executions of civilians, having boasted of killing more than 2,000 people.
The Accreditation Commission for Health Care (ACHC) is a United States-based non-profit health care accrediting organization. It represents an alternative to the Joint Commission and CHAP, The Community Health Accreditation Program. ACHC was established in 1985 by home care health providers to create an accreditation option which was more focused on the needs of small providers. The process began in Raleigh, North Carolina, with the group incorporated in August 1986. The first accredited organization was awarded certification in January 1987. The company began offering services on a national level in 1996. Today, ACHC offers nineteen accreditation programs, nine of which are CMS approved (Acute Care Hospital, Ambulatory Surgery Center, Clinical Laboratory, Critical Access Hospital, DMEPOS, Home Health, Home Infusion Therapy, Hospice, Renal Dialysis).
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 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.