This is a working overview of RP-HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-03. Anything still debated is marked as such rather than presented as settled.
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。
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。
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
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.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
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.
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.
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.
Imaging compounds, notably Pittsburgh compound B, (6-OH-BTA-1, a thioflavin), can selectively bind to amyloid beta in vitro and in vivo. This technique, combined with PET imaging, is used to image areas of plaque deposits in those with Alzheimer's.
== See also == Category:Cutaneous conditions Dermatology List of conditions associated with café au lait macules List of contact allergens List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer List of cutaneous conditions associated with internal malignancy List of cutaneous conditions caused by mutations in keratins List of cutaneous neoplasms associated with systemic syndromes List of cutaneous conditions caused by problems with junctional proteins List of dental abnormalities associated with cutaneous conditions List of genes mutated in cutaneous conditions List of genes mutated in pigmented cutaneous lesions List of histologic stains that aid in diagnosis of cutaneous conditions List of human leukocyte antigen alleles associated with cutaneous conditions List of immunofluorescence findings for autoimmune bullous conditions List of inclusion bodies that aid in diagnosis of cutaneous conditions List of keratins expressed in the human integumentary system List of migrating cutaneous conditions List of mites associated with cutaneous reactions List of radiographic findings associated with cutaneous conditions List of specialized glands within the human integumentary system List of spiders associated with cutaneous reactions List of target antigens in pemphigoid List of target antigens in pemphigus List of verrucous carcinoma subtypes List of xanthoma variants associated with hyperlipoproteinemia subtypes
Funding for research in this field was in part provided by the Muscular Dystrophy Association and the Acid Maltase Deficiency Association in the US and by the Association of Glycogen Storage Disease in the UK, as well as the International Pompe Association. John Crowley became involved in the fund-raising efforts in 1998 after two of his children were diagnosed with Pompe. He joined the company Novazyme in 1999, which was working on enzyme replacement treatment for Pompe. Novazyme was sold to Genzyme in 2001 for over US$100 million. The 2010 film Extraordinary Measures is based on Crowley's search for a cure. As of 2019, many biomedical companies are developing gene therapy in hopes of helping the body create alpha-glucosidase on its own. In 2021, in-utero enzyme replacement therapy infusions were provided to the fetus of an Ottawa, Ontario, mother who had had two previous children with Pompe disease. The medical team was a collaboration between Ottawa Hospital, Children's Hospital of Eastern Ontario, the University of California, San Francisco, and Duke University. The child, born in June 2021, is thriving as of November 2022.
Sources: en.wikipedia.org
== History == President Dr. Arif Alvi granted approval for the reconstitution of the NEC on 8 June 2022, in accordance with the guidelines outlined in Article 156 of the Constitution. The NEC consists of a total of 13 members, led by the Prime Minister of Pakistan, who serves as the chairman. In addition to the chief ministers from all provinces, the council includes various federal ministers and nominated representatives from different political parties and provinces.
The three substrates of this enzyme are glutathione amide disulfide, reduced nicotinamide adenine dinucleotide (NADH), and a proton. Its products are glutathione amide and oxidised NAD+. Glutathione amide reductase is a dimeric flavoprotein (FAD).
Liberation – How is the active pharmaceutical ingredient disintegrated (for solid oral forms (breaking down into smaller particles), dispersed, or dissolved from the medication? Absorption – How is the active pharmaceutical ingredient absorbed (through the skin, the intestine, the oral mucosa)? Distribution – How does the active pharmaceutical ingredient spread through the organism? Metabolism – Is the active pharmaceutical ingredient converted chemically inside the body, and into which substances. Are these active (as well)? Could they be toxic? Excretion – How is the active pharmaceutical ingredient excreted (through the bile, urine, breath, skin)? Drug metabolism is assessed in pharmacokinetics and is important in drug research and prescribing. Pharmacokinetics is the movement of the drug in the body, it is usually described as 'what the body does to the drug' the physico-chemical properties of a drug will affect the rate and extent of absorption, extent of distribution, metabolism and elimination. The drug needs to have the appropriate molecular weight, polarity etc. in order to be absorbed, the fraction of a drug that reaches the systemic circulation is termed bioavailability, this is simply a ratio of the peak plasma drug levels after oral administration and the drug concentration after an IV administration (first pass effect is avoided and therefore no amount drug is lost). A drug must be lipophilic (lipid soluble) in order to pass through biological membranes because biological membranes are made up of a lipid bilayer (phospholipids etc.).
Sources: en.wikipedia.org
Common adverse drug reactions associated with the use of buprenorphine, similar to those of other opioids, include nausea and vomiting, drowsiness, dizziness, headache, memory loss, cognitive and neural inhibition, perspiration, itchiness, dry mouth, shrinking of the pupils of the eyes (miosis), orthostatic hypotension, male ejaculatory difficulty, decreased libido, and urinary retention. Constipation and central nervous system (CNS) effects are seen less frequently than with morphine. Central sleep apnea has also been reported as a side effect of long-term buprenorphine use.
The UK NHS in 2019 listed Humira, Amgevita, Hulio, Hyrimoz, Idacio, and Imraldi as biosimilars available on (almost free) prescription, to be updated in February 2022. The annual cost of adalimumab, the costliest NHS drug, was expected to drop from £400m to £100m by 2021, the biggest saving in NHS history from a single drug negotiation. The best-selling drugs list published by Genetic Engineering & Biotechnology News, shows that Humira occupied the #1 position for 2015 (US$14.012 billion) and 2016 (US$16.078 billion) From 2012 until the US patent expired in 2016, Humira led the list of top-selling pharmaceutical products, and in 2016, it had US$16 billion of global sales. AbbVie reported that Humira achieved US$18.427 billion of sales in 2017. Humira had the largest worldwide drug sales in 2019 and 2020 of US$19.7bn and US$20.4bn respectively.
Because the development and consolidation of gender identity is a diverse process among trans adolescents, it is recommended that healthcare professionals offer a respectful environment for clients—especially youth—to explore and express different facets of their identity, including the need for gender-affirming care. It is important that gender exploration is not used to delay gender-affirming care or attempt tracing trans identity to pathologies, as such approaches would be tantamount to conversion practices, which are known for causing significant harm.
Sources: en.wikipedia.org
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.