This is a working overview of freeze-thaw, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
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.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
| Property | Value | Notes |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Heptapeptide; ACTH(4-10) analog extended at C-terminus |
| Molecular mass | ~813.9 Da | Free peptide, unmodified |
| Appearance | White to off-white powder | Typical lyophilized solid |
| Solubility | Soluble in water and saline | Also soluble in common aqueous buffers |
| Storage (solid) | -20 °C, desiccated | Protect from moisture and repeated thawing |
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.
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.
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
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.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
== Medical uses == CEEs are a form of hormone therapy used in women. It is used most commonly in postmenopausal women who have had a hysterectomy to treat hot flashes, and burning, itching, and dryness of the vagina and surrounding areas. It must be used in combination with a progestogen in women who have not had a hysterectomy. For women already taking the medication, it can be used to treat osteoporosis, although it is not recommended solely for this use. Some lesser known uses are as a means of high-dose estrogen therapy in the treatment of breast cancer in both women and men and in the treatment of prostate cancer in men. It has been used at a dosage of 2.5 mg three times per day (7.5 mg/day total) for prostate cancer. CEEs are specifically approved in countries such as the United States and Canada for the treatment of moderate to severe vasomotor symptoms (hot flashes) and vulvovaginal atrophy (atrophic vaginitis, atrophic urethritis) associated with menopause, hypoestrogenism due to hypogonadism, ovariectomy, or primary ovarian failure, abnormal uterine bleeding, the palliative treatment of metastatic breast cancer in women, the palliative treatment of advanced androgen-dependent prostate cancer in men, and the prevention of postmenopausal osteoporosis. The intravenous formulation of CEEs is specifically used to rapidly limit bleeding in women with hemorrhage due to dysfunctional uterine bleeding.
=== Violence === The heightened levels of violence and abuse that transgender people experience result in unique adverse effects on bodily and mental health. Specifically, in resource-constrained settings where non-discriminatory policies may be limited or not enforced, transgender people may encounter high rates of stigma and violence which are associated with poor health outcomes. Studies in countries of the Global North show higher levels of discrimination and harassment in school, workplace, healthcare services and the family when compared with cisgender populations, situating transphobia as a key health risk factor for the physical and mental health of transgender people. Victimization is often the outcome to disclosure for transgender individuals. Transgender individuals are pressured to conform to gender norms which make them vulnerable for victimization by peers and parents. A study done by Grossman and D'Augelli reported that transgender youth feared that may face physical and sexual violence because of their experience with harassment and discrimination. The youth also express how individuals only see them for their gender and sexuality rather than their personal traits. Many of the youth have also dropped out or experience academic decline because of the constant harassment. Victimization started on average for transgender at the age of 13, while physical abuse started at an average age 14.
== Recombinant protein-based textiles == Collagen, fibroin, gelatin, casein, and actin are naturally from animal products. Collagen and silk are the most attractive biopolymers for developing biotextiles. Collagen can be produced from a plethora of organisms and renewable sources. Collagen's repeating amino acid sequence allows it to form a stable secondary protein structure of triple helices. These helices can further assemble into quaternary structures, allowing collagen to take on the form of fibrillar proteins. These protein building blocks could biofabricate abrasion-resistant, water-resistant, breathable, lightweight and durable materials with characteristics similar to leather. Natural silk has remarkable strength. The fibroin protein in silk consists of long, repetitive chains of amino acids, predominantly glycine, alanine, and serine. These amino acids are arranged in a specific sequence, forming a unique molecular structure that contributes to silk's remarkable properties. Silk has high tensile strength that can be attributed to its nano-crystalline and molecular structure (hydrogen bonds & β-sheet structure) and high degree of orientation. Significant efforts have been made to obtain recombinant silk fibroin, principally from the spider, dragline, or silkworm through genetic alteration. The developed protein is later isolated and processed into threads by techniques such as spinning.
=== Acquired and inherited enzyme deficiencies === Downregulation of kynurenine 3-monooxygenase (KMO) can be caused by genetic polymorphisms, cytokines, or both. KMO deficiency leads to an accumulation of kynurenine and to a shift within the tryptophan metabolic pathway towards kynurenic acid and anthranilic acid. Deficiencies of one or more enzymes on the kynurenine pathway leads to an accumulation of intermediate metabolic products which can cause effects depending on their concentration, function and their inter-relation with other metabolic products. For example, kynurenine 3-monooxygenase deficiency is associated with disorders of the brain (such as schizophrenia and tic disorders) and of the liver. The mechanism behind this observation is typically a blockade or bottleneck situation at one or more enzymes on the kynurenine pathway due to the effects of indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) and/or due to genetic polymorphisms afflicting the particular genes. Dysfunctional states of distinct steps of the kynurenine pathway (such as kynurenine, kynurenic acid, quinolinic acid, anthranilic acid, 3-hydroxykynurenine) have been described for a number of disorders, for example:
Sources: en.wikipedia.org
JINR did not propose a name after their first report claiming synthesis of element 105, which would have been the usual practice. This led LBL to believe that JINR did not have enough experimental data to back their claim. After collecting more data, JINR proposed the name bohrium (Bo) in honor of the Danish nuclear physicist Niels Bohr, a founder of the theories of atomic structure and quantum theory; they soon changed their proposal to nielsbohrium (Ns) to avoid confusion with boron. Another proposed name was dubnium. When LBL first announced their synthesis of element 105, they proposed that the new element be named hahnium (Ha) after the German chemist Otto Hahn, the "father of nuclear chemistry", thus creating an element naming controversy. In the early 1970s, both teams reported synthesis of the next element, element 106, but did not suggest names. JINR suggested establishing an international committee to clarify the discovery criteria. This proposal was accepted in 1974 and a neutral joint group formed. Neither team showed interest in resolving the conflict through a third party, so the leading scientists of LBL—Albert Ghiorso and Glenn Seaborg—traveled to Dubna in 1975 and met with the leading scientists of JINR—Georgy Flerov, Yuri Oganessian, and others—to try to resolve the conflict internally and render the neutral joint group unnecessary; after two hours of discussions, this failed. The joint neutral group never assembled to assess the claims, and the conflict remained unresolved.
The raid failed, and the dissidents and mercenaries were killed or captured. The owner of Silvercorp, an ex-US special operations sergeant, said he met with Trump administration officials about the plan. Absent any vote tallies, Maduro was declared the winner of the 2024 Venezuelan presidential election by the government-controlled National Electoral Council; the result was "widely condemned as fraudulent by international observers and the opposition" who found statistical improbabilities in the results. The opposition showed evidence and vote tallies that its candidate, Edmundo González, had won a majority, matching the results of pre-election opinion polls, who was "widely believed to have won [the] election, and by a landslide", according to The New York Times. The Venezuelan government issued an arrest warrant for González, who left the country and was granted asylum in Spain. In January 2025, the Biden administration recognized González as Venezuela's legitimate president-elect. The Trump administration had sought to prosecute Maduro on narco-terrorism charges since at least 2020. At a 2023 press conference, Trump said, "Venezuela was about to collapse. We would have taken over it... [and] kept all that oil."
In Winter 1996, Kenyon's co-authored paper, "The RNA World: A Critique," appeared in Origins and Design, a now defunct creationist journal where he was on the Editorial Advisory Board. He continued publicly arguing in favor of creationism, notably at the 1998 International Conference on Creationism. Currently, Kenyon is a speaker, writer, and board member for the Kolbe Center, a Catholic YEC group. In 2008, Kenyon endorsed a young Earth creationist book promoted by the Center.
== Structure and functions == Cryo-electron microscopy (Cryo-EM) study has revealed the structural architecture of PLOD3 within the lysyl O-linked glycosylation complex (KOGG complex), which plays a crucial role in procollagen maturation. The KOGG complex consists of a PLOD3 (LH3) dimer, a Procollagen galactosyltransferase 1 (ColGalT1) dimer, and UDP-bound cofactors, orchestrating the hydroxylation (by PLOD3) and dual glycosylation (galactosylation by ColGalT1 and glucosylation by PLOD3) of lysine residues in the endoplasmic reticulum (ER) lumen. These modifications are essential for collagen cross-linking, fibrillogenesis, and overall structural integrity. Additionally, the structural study suggests that the KOGG complex can polymerize into a larger, fiber-like enzyme supercomplex, which may further regulate collagen modification and assembly. Defects in PLOD3 function or glycosylation efficiency have been implicated in connective tissue disorders, including osteogenesis imperfecta and fibrosis-related diseases.
=== Primary glaucoma and its variants === Primary glaucoma (H40.1-H40.2) includes primary open-angle glaucoma (chronic open-angle, chronic simple, glaucoma simplex), which can be high-tension or low-tension, and primary angle closure glaucoma (primary closed-angle, narrow-angle, pupil-block, acute congestive), which can manifest as acute, chronic, intermittent, or superimposed on chronic open-angle closure glaucoma (also called "combined mechanism" glaucoma). Other variants of primary glaucoma include:
Sources: en.wikipedia.org
Semax is a synthetic seven-amino-acid peptide derived from a fragment of corticotropin. It is used in Russia as a nasal preparation, while elsewhere it is studied as a research compound. It is not approved as a medicine in most countries.
Its sequence corresponds to the 4-10 region of corticotropin extended by three residues. This fragment lacks the region responsible for adrenal steroid release, so it is explored for neural rather than hormonal effects. The relationship explains the compound's classification among ACTH-derived peptides.
It holds approval in Russia for several neurological indications as a nasal spray or drop formulation. Regulatory agencies in the United States and the European Union have not approved it. Products sold elsewhere are generally labeled for research use only.
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.