lyophilized powder comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-02-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
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.
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.
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.
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.
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.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
== Oxygen-16 == Oxygen-16 (symbol: 16O or 168O) is a stable isotope of oxygen, with 8 neutrons and 8 protons in its nucleus, making it a doubly magic nuclide. It is the most abundant isotope of oxygen, accounting for about 99.76% of all oxygen. The relative and absolute abundances of oxygen-16 are high because it is a principal product of stellar evolution. It can be made by stars that were initially made exclusively of hydrogen. Most oxygen-16 is synthesized at the end of the helium fusion process in stars. The triple-alpha process creates carbon-12, which captures an additional helium-4 to make oxygen-16. It is also created by the neon-burning process. Prior to the definition of the dalton based on 12C, one atomic mass unit was defined as one sixteenth of the mass of an oxygen-16 atom. Since physicists referred to 16O only, while chemists meant the natural mix of isotopes, this led to slightly different mass scales.
== In diabetes == The fluctuations in the levels of chaperone HSP70 affect the homeostasis. Diabetes leads to several microvasculature and microvasculature diseases like retinopathy, Toll like receptors are integral part of innate immune system and eHSP70 binds to toll like receptors and activates the MyD88 pathway, further stimulating NF-kB, cytokines like TNFα and IL1 β, increased production of reactive oxygen species contributing to insulin resistance and diabetes. Whereas there is decrease in the levels of iHSP70.
=== Stagnation and a forfeited World Cup (1976–1986) === Runners-up status brought no lasting improvement. Colombia failed to win any of their four matches in the 1978 qualifiers, managing one goal across the group and losing 6–0 in Rio de Janeiro. At the 1979 Copa América they again finished level on points with Chile after beating them 1–0 in Bogotá and putting four past Venezuela, only to be eliminated on goal difference following a 2–0 defeat in Santiago. The 1982 campaign, overseen by the Argentine Carlos Bilardo, yielded two points from four matches and no victories, Hernán Darío Herrera scoring three of Colombia's four goals. A second-place group finish behind Peru ended the 1983 Copa América campaign.
=== Other methods === Although of no commercial significance, many other routes to benzene exist. Phenol and halobenzenes can be reduced with metals. Benzoic acid and its salts undergo decarboxylation to benzene. The reaction of the diazonium compound derived from aniline with hypophosphorus acid gives benzene. Alkyne trimerisation of acetylene gives benzene. Complete decarboxylation of mellitic acid gives benzene.
== Examples == Strategies for improving platinum-based anticancer drugs usually involve changes in the neutral spectator ligands, changes in the nature of the anions (halides vs various carboxylates), or changes in the oxidation state of the metal (Pt(II) vs Pt(IV)). Nanotechnology has been explored to deliver platinum more efficiently in the case of lipoplatin, which is introduced into the tumor sites thereby reducing the chance of toxicity. Cisplatin was the first to be developed. Cisplatin is particularly effective against testicular cancer; the cure rate was improved from 10% to 85%. Similarly, the addition of cisplatin to adjuvant chemotherapy led to a marked increase in disease-free survival rates for patients with medulloblastoma - again, up to around 85%. This application of cisplatin was developed by pediatric oncologist Roger Packer in the early 1980s.
Sources: en.wikipedia.org
Fluoroalanine, specifically 3-fluoro-alanine, is a fluorinated analogue of the amino acid alanine. Historically considered as an antibiotic, it also has potential applications as a radioactive tracer in positron emission tomography (PET).
== Research == Multiple studies have shown that LDN has promise as a treatment for chronic pain, some autoimmune disorders, and cancers. Studies on the efficacy of LDN for multiple sclerosis have been inconclusive. Clinical trials for its use as treatment of fibromyalgia were initiated in 2021. LDN is also being studied in long COVID. A 2018 therapeutic utilization review concluded that LDN may be an appropriate option for treatment of fibromyalgia and irritable bowel syndrome, but that "proper clinical trials are needed in order to establish evidence that could lead to correct indications, mode of administration, and other aspects necessary for effective clinical pharmacology of [low-dose naltrexone]." The UK's National Health Service echoed this sentiment in 2020. In a 2013 paper published in Arthritis & Rheumatology, authors Jarred Younger and Sean Mackey reported reduced circulating pro‑inflammatory cytokines and self‑reported pain in fibromyalgia patients using LDN. A 2018 review summarized mixed trial outcomes and emphasized methodological limitations. A 2023 systematic review published in the Australian Journal of General Practice found that preliminary research into the use of LDN as a treatment for fibromyalgia is promising. All clinical studies examined showed statistically significant improvements in pain and pain tolerance with mild side effects; however, sample sizes were small and the evidence is inconclusive.
In relation to its selectivity for the AR, unlike steroidal antiandrogens (SAAs) such as CPA and megestrol acetate (MGA), bicalutamide does not interact importantly with other steroid hormone receptors (including the ERsTooltip estrogen receptors, PRsTooltip progesterone receptors, GRTooltip glucocorticoid receptor, or MRTooltip mineralocorticoid receptor), and in accordance, has no clinically relevant additional, off-target hormonal activity (estrogenic or antiestrogenic, progestogenic or antiprogestogenic, glucocorticoid or antiglucocorticoid, or mineralocorticoid or antimineralocorticoid). However, it has been reported that bicalutamide has weak affinity for the progesterone receptor (PR) (~100- to 500-fold lower than for the AR), where it acts as an antagonist (with only ~12-fold lower functional inhibition relative to the AR in one study). Hence, bicalutamide may have some antiprogestogenic activity, although the clinical relevance of this is unknown. Bicalutamide does not inhibit 5α-reductase and is not known to inhibit other enzymes involved in androgen steroidogenesis (e.g., CYP17A1). Although bicalutamide does not bind to the ERs, it can increase estrogen levels secondarily to blockade of the AR when used as a monotherapy in males, and for this reason, the medication can indirectly activate the ERs to a degree and hence have some indirect estrogenic effects in men.
Hence, even though nihonium is in group 13, it has several properties similar to the group 17 elements. (Tennessine in group 17 has some group-13-like properties, as it has three valence electrons outside the 7s2 7p2 closed shell.) Nihonium is expected to be able to gain an electron to attain this closed-shell configuration, forming the −1 oxidation state like the halogens (fluorine, chlorine, bromine, iodine, and astatine). This state should be more stable than it is for thallium as the SO splitting of the 7p subshell is greater than that for the 6p subshell. Nihonium should be the most electronegative of the metallic group 13 elements, even more electronegative than tennessine, the period 7 congener of the halogens: in the compound NhTs, the negative charge is expected to be on the nihonium atom rather than the tennessine atom. The −1 oxidation should be more stable for nihonium than for tennessine. The electron affinity of nihonium is calculated to be around 0.68 eV, higher than thallium's at 0.4 eV; tennessine's is expected to be 1.8 eV, the lowest in its group. It is theoretically predicted that nihonium should have an enthalpy of sublimation around 150 kJ/mol and an enthalpy of adsorption on a gold surface around −159 kJ/mol.
Sources: en.wikipedia.org
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
一般不建议常温长期保存。多数说明指向 -20 °C 冷冻避光。常温运输通常被视为短期可接受，但会加快降解风险。