A practical reference on reversed-phase HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-01-24 and is reviewed periodically as new material appears.
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.
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.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
| 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 |
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. 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.
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.
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 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
==== Tax deduction for energy efficient commercial buildings ==== The tax credit for energy efficient commercial buildings is no longer available for any property if the construction begins after June 30, 2026.
=== TikTok Notes === In April 2024, TikTok users started receiving notifications that their current and future picture posts would be shown on a new app called TikTok Notes. The app was not released yet; however, TikTok confirmed it was being worked on. TikTok Notes was a direct competitor to Instagram for photo sharing. Jasmine Enberg, a principal social media analyst at eMarketer, observes that launching Notes as a separate app, instead of as a new feature in TikTok, may have been done in response to regulatory and consumer scrutiny. On 18 April 2024, Notes first released to users in Canada and Australia for limited testing. On 1 April 2025, it was announced that Notes would be shut down on 8 May. It went defunct on 8 May 2025.
Nearly two billion people in the developing world are deficient in zinc. Groups at risk include children in developing countries and the elderly with chronic illnesses. In children, it causes an increase in infection and diarrhea and contributes to the death of about 800,000 children worldwide per year. The World Health Organization advocates zinc supplementation for severe malnutrition and diarrhea. Zinc supplements help prevent disease and reduce mortality, especially among children with low birth weight or stunted growth. However, zinc supplements should not be administered alone, because many in the developing world have several deficiencies, and zinc interacts with other micronutrients. While zinc deficiency is usually due to insufficient dietary intake, it can be associated with malabsorption, acrodermatitis enteropathica, chronic liver disease, chronic renal disease, sickle cell disease, diabetes, malignancy, and other chronic illnesses. In the United States, a federal survey of food consumption determined that for women and men over the age of 19, average consumption was 9.7 and 14.2 mg/day, respectively. For women, 17% consumed less than the EAR, for men 11%. The percentages below EAR increased with age. The most recent published update of the survey (NHANES 2013–2014) reported lower averages – 9.3 and 13.2 mg/day – again with intake decreasing with age. Symptoms of mild zinc deficiency are diverse.
Moscow, as the city designated by the Constitution of the Russian Federation as the seat of federal authority, contains the country's federal legislative, executive, and judicial authorities—except for the Constitutional Court of the Russian Federation, which has been located in Saint Petersburg since 2008. The supreme executive authority—the Government of the Russian Federation—is located in the House of the Government of the Russian Federation (the White House) on the Krasnopresnenskaya Embankment in the center of Moscow. The State Duma is on Okhotny Ryad (street). The Federation Council is in a building on Bolshaya Dmitrovka (street). The Supreme Court of the Russian Federation is also in Moscow. The Moscow Kremlin is the official residence of the President of the Russian Federation. The president's working residence in the Kremlin is located in the Senate Palace.
Sources: en.wikipedia.org
Records of attempts at pregnancy testing have been found as far back as the ancient Greek and ancient Egyptian cultures. The ancient Egyptians watered bags of wheat and barley with the urine of a possibly pregnant woman. Germination indicated pregnancy. The type of grain that sprouted was taken as an indicator of the fetus's sex. Hippocrates suggested that a woman who had missed her period should drink a solution of honey in water at bedtime: resulting abdominal distention and cramps would indicate the presence of a pregnancy. Avicenna and many physicians after him in the Middle Ages performed uroscopy, a nonscientific method to evaluate urine. Selmar Aschheim and Bernhard Zondek introduced testing based on the presence of human chorionic gonadotropin (hCG) in 1928. Early studies of hCG had concluded that it was produced by the pituitary gland. In the 1930s, Doctor Georgeanna Jones discovered that hCG was produced not by the pituitary gland, but by the placenta. This discovery was important in relying on hCG as an early marker of pregnancy. In the Aschheim and Zondek test, an infantile female mouse was injected subcutaneously with urine of the woman to be tested, and the mouse later was killed and dissected. Presence of ovulation indicated that the urine contained hCG and meant that the subject was pregnant. A similar test was developed using immature rabbits.
Grannygate – scandal in March 2000 over the eligibility of Shane Howarth and Brett Sinkinson representing the Wales national team Kamp Staaldraad – controversial training camp for the Springboks (South Africa's national rugby union team) before the 2003 Rugby World Cup "Bloodgate" – a scheme by the English rugby union club Harlequins to fake an injury to wing Tom Williams to allow a blood replacement to be brought on at a critical moment in their 2009 Heineken Cup quarterfinal against Leinster. The scheme, which included deliberately cutting Williams' mouth open after the match in order to cover up the fake injury, ultimately led to Quins head coach Dean Richards being banned from the sport for three years.
==== Formation of the UPP ==== The Unidade de Polícia Pacificadora (Pacifying Police Units) or UPP was a security program in Rio de Janeiro that aimed to reclaim favelas from criminal organizations, such as CV, ADA, and TCP, through community policing. The strategy worked in two parts: deployment of the Military Police of Rio (PMERJ) into the favelas, and then increasing the amount of police officers who were meant to interact with the community through units, in hopes of creating a healthier relationship between favela residents and law enforcement than what existed in years prior. For decades, interactions with police in Rio de Janeiro were abrasive; violent conflicts between drug traffickers and the police led to widespread civilian casualties, and numerous instances of abuses of power by the police led to a general distrust by favela residents. The creation of the UPP aimed to both restructure the police force and its interactions with civilians, while also deterring criminal activity leading up to the 2014 World Cup and 2016 Summer Olympics. A secondary component of the UPP plan was the creation of UPP Social, which aimed to address the social welfare needs of the favelas by UPP units. This included improvements to sanitation, education, and healthcare, among other social issues. In 2008, the first UPP was set up in the Santa Marta favela, with more quickly following -- coalescing in 32 units overall, spanning all of Rio de Janeiro's zones (though most were located in Zona Norte).
Sources: en.wikipedia.org
== Veterinary uses == In 2019, GS-441524 was shown to have promise for treating feline infectious peritonitis caused by a coronavirus. It has not been evaluated or approved by the US Food and Drug Administration (FDA) for the treatment of feline coronavirus or feline infectious peritonitis but has been available since 2019, through websites and social media as an unregulated black market substance. Because GS-441524 is the main circulating metabolite of remdesivir and because GS-441524 has similar potency against SARS-CoV-2 in vitro, some researchers have argued for the direct administration of GS-441524 as a COVID‑19 treatment.
While the degree of saturation is used to differentiate fatty acids and their chemical composition, the length of the aliphatic hydrocarbon chain also influences fatty acids and their biological roles. Carbon chain lengths can vary greatly within each class of fatty acids, with some having as few as 12-carbons (i.e., dodecanoic acid) and others having as many as 30-carbons (i.e., triacontanoic acid). Fatty acid chain length is known to shape several biophysical properties of the cellular membrane, such as membrane fluidity, microdomain formation, and the assembly of membrane-associated signaling platforms. Chain length can also alter cellular susceptibility to death or survival through modulation of membrane properties. Interestingly, mammals are unable to synthesize polyunsaturated fatty acids de novo. While mammalian cells express the enzymes necessary for the conversion of carbohydrate-derived and protein-derived carbons into saturated and monounsaturated fatty acids, they lack the desaturase enzymes required for production of the limiting-reagent in polyunsaturated fatty acid synthesis. Thus, polyunsaturated fatty acids are considered essential, and must be acquired through dietary consumption. Thus, for all non-essential fatty acids, FA synthesis occurs de novo, wherein fats are derived from simple precursors like carbohydrates (i.e., glucose) via acetyl-CoA. De novo fatty acid synthesis primarily occurs in the cytosol of hepatocytes (i.e., in the liver) and adipocytes (i.e., in adipose tissue or fat).
==== Congress of South African Students ==== Accounts of the uprising typically accord a central role to black young adults – known in the anti-apartheid movement as "young lions" or "comrades" – who became the "shock troops" of the revolt. Their largest and most prominent organisational base was COSAS, another UDF affiliate that was founded in 1979, with a local branch in Vaal from March 1980. COSAS apparently played an important role in politicising the youth of Vaal, including by encouraging them to support the VCA, and many of the most militant participants in the uprising were formally or informally affiliated to COSAS.
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.
Semax is based on the ACTH(4-10) fragment, a seven-amino-acid segment of adrenocorticotropic hormone. The synthetic peptide retains the core sequence while removing regions associated with endocrine activity. This modification is intended to isolate effects on the nervous system.