RP-HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-07-21. Numbers and descriptions here follow the published literature rather than marketing material.
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.
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
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。
| Property | Value | Notes |
|---|---|---|
| Solid storage temperature | -20 °C or below | Desiccated and protected from light |
| Solution storage temperature | -80 °C as single-use aliquots | Avoid repeated freeze-thaw cycles |
| Purity assessment method | RP-HPLC, around 214 nm | Reported as main-peak area percent |
| Identity confirmation method | ESI-MS or MALDI-TOF | Measured mass compared with calculated mass |
| Common synonyms | ACTH(4-10) analog; Met-Glu-His-Phe-Pro-Gly-Pro | Also written as Semaxum in some sources |
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.
Rennie's 1833 supplement to the pharmacopeias admitted its use as an "expectorant, diuretic, and emmenagogue" in doses of 10 grains to 1 scruple (0.6–1.3g) of the powdered dried herb, but dismissed the use of the Pennyroyal Water (Aqua Pulegii) as "popularly but erroneously supposed" to be an abortifacient [no mention is made of toxicity]. Chemicals in the pennyroyal plant cause the uterine lining to contract, causing a woman's uterine lining to shed. Since the U.S. Congress passed the Dietary Supplement Health and Education Act in October 1994, all manufactured forms of pennyroyal in the United States have carried a warning label against its use by pregnant women, but pennyroyal is not regulated by the U.S. Food and Drug Administration. At least one study has shown pennyroyal oil to have potent acaricidal activity against house dust mites.
The regular formation of alpha-sheet by unfolded proteins inevitably involves many L amino acid residues readily adopting the alphaL conformation, which appears at first sight to go against textbook chemistry, which is that, of the 20 amino acids, it is glycine that strongly favours this conformation. The conundrum is resolved by realizing that the alphaL region comprises two overlapping areas, here called γL and αL, which should be considered separately. It turns out that, while the γL conformation is adopted, almost exclusively, by glycine, the αL conformation of alpha-sheet is more commonly, or about as commonly, adopted by any of 15 L-amino acids compared to glycine, the exceptions being proline, threonine, valine and isoleucine, which are rare at this conformation. Hence, of the 20 amino acids, 16 readily adopt the αL conformation.
Taiwan's migrant worker population—estimated in 2018 to be up to 660,000 in number—have reportedly faced slavery-like conditions involving sexual abuse in the domestic work sector and forced labor in fishing sectors. Taiwan is among a minority of places in the world that legally allows labor brokers to charge migrant workers for services which elsewhere are covered by employers as human resource costs. A few Taiwanese universities have reportedly tricked students from Eswatini, Uganda and Sri Lanka into forced labour at factories as payment for the university programs. Some charity groups in 2007 also insisted that foreign women—mostly from China and Southeast Asia—were being forced into prostitution, although local police in Tainan disagreed and said they deliberately came to Taiwan "to sell sex".
Sources: en.wikipedia.org
CPG is commonly defined by its pore size. In oligonucleotide chemistry, pore sizes of 500, 1000, 1500, 2000, and 3000 Å are used to allow the preparation of about 50, 80, 100, 150, and 200-mer oligonucleotides, respectively. To make native CPG suitable for further processing, the surface of the material is treated with (3-aminopropyl)triethoxysilane to give aminopropyl CPG. The aminopropyl arm may be further extended to result in long chain aminoalkyl (LCAA) CPG. The amino group is then used as an anchoring point for linkers suitable for oligonucleotide synthesis (see below). MPPS suitable for oligonucleotide synthesis is a low-swellable, highly cross-linked polystyrene obtained by polymerization of divinylbenzene (min 60%), styrene, and 4-chloromethylstyrene in the presence of a porogeneous agent. The macroporous chloromethyl MPPS obtained is converted to aminomethyl MPPS.
In the eighteenth century, gelatine from calf's feet, isinglass and hartshorn was coloured blue with violet juice, yellow with saffron, red with cochineal and green with spinach and allowed to set in layers in small, narrow glasses. It was flavoured with sugar, lemon juice and mixed spices. This preparation was called jelly; the English cookery writer Hannah Glasse was the first to record the use of this jelly in trifle in her book The Art of Cookery, first published in 1747. Preparations on making jelly (including illustrations) appear in the best selling cookbooks of the English writers Eliza Acton and Isabella Beeton in the 19th century. Due to the time-consuming nature of extracting gelatine from animal bones, gelatine desserts were a status symbol up until the mid-19th century as it indicated a large kitchen staff. Jelly molds were very common in the batteries de cuisine of stately homes.
In recent years, the clinical understanding of the FDA's "black box" warning has evolved to focus on the balance between medication risks and the risks of untreated depression. While the 2004 and 2006 warnings regarding increased suicidal ideation in children and young adults (under 25) remain, long-term data published through 2024 suggests that these warnings may have led to an unintended decline in depression treatment, which some studies correlate with an increase in suicide deaths among adolescents. Statistical meta-analyses updated in 2022 confirm that while the risk of suicidal thoughts in youth on antidepressants like fluoxetine is approximately twice that of a placebo (4% vs 2%), there remains no statistically significant increase in completed suicides across dozens of pediatric trials. Furthermore, recent data continues to show a protective effect in older populations; for adults aged 65 and older, antidepressant use is associated with a statistically significant decrease in suicidality. Regarding specific treatments, research published between 2021 and 2023 reinforces that fluoxetine is most effective and carries the lowest risk of adverse behavioral events when paired with psychotherapy. A 2022 meta-analysis found that combination therapy (medication plus CBT) resulted in a lower incidence of suicidal events compared to fluoxetine alone.
== Production == Yeast extracts in general are produced in three steps: fermentation (growing the yeast), disruption (breaking of the cells), and separation (to keep the soluble part). Although the vast majority of yeast extract spreads are made using von Liebig's traditional approach of heat-autolysis using surplus yeast from beer brewing, other methods do exist for producing specialized types. In terms of fermentation, spent beer yeast is commonly contaminated with the bitter compounds from hops, requiring a "debittering" step to wash out most of this undesired flavor. Yeast from other sources are not affected by this issue. Spent brewer's yeast is also quite biodiverse, containing yeasts other than traditional Saccharomyces cerevisiae and sometimes beer spoilage-causing lactic acid bacteria too. For disruption of the cell, some physical and chemical methods may be used in place of the heat-autolysis process. Doing so may allow specific compounds to be extracted or to produce an extract without the hydrolysis of cell contents (as in autolysis) happening. Autolysis can be assisted with added enzymes; for example, additional nuclease would enhance the release of nucleosides from RNA. Separation removes insoluble parts, mainly the yeast's cell wall, from the extract. Cell wall can be separated into two commercially useful parts: the glucans as "yeast β-glucan" and the mannans further processed into mannan-oligosaccharide (MOS). The product is finally concentrated by drying, into a thick paste or a dry powder.
Sources: en.wikipedia.org
=== Rheopectic or anti-thixotropic === There are also fluids whose strain rate is a function of time. Fluids that require a gradually increasing shear stress to maintain a constant strain rate are referred to as rheopectic. An opposite case of this is a fluid that thins out with time and requires a decreasing stress to maintain a constant strain rate (thixotropic).
== Functions == There are currently ten known prostaglandin receptors on various cell types. Prostaglandins ligate a sub-family of cell surface seven-transmembrane receptors, G-protein-coupled receptors. These receptors are termed DP1-2, EP1-4, FP, IP1-2, and TP, corresponding to the receptor that ligates the corresponding prostaglandin (e.g., DP1-2 receptors bind to PGD2). The diversity of receptors means that prostaglandins act on an array of cells and have a wide variety of effects such as:
==== Nucleic acids ==== A significant obstacle to using LNPs as a delivery vehicle for nucleic acids is that in nature, lipids and nucleic acids both carry a negative electric charge—meaning they do not easily mix with each other. While working at Syntex in the mid-1980s, Philip Felgner pioneered the use of artificially-created cationic lipids (positively-charged lipids) to bind lipids to nucleic acids in order to transfect the latter into cells. However, by the late 1990s, it was known from in vitro experiments that this use of cationic lipids had undesired side effects on cell membranes. During the late 1990s and 2000s, Pieter Cullis, while at the University of British Columbia, developed ionizable cationic lipids which are "positively charged at an acidic pH but neutral in the blood." Cullis also led the development of a technique involving careful adjustments to pH during the process of mixing ingredients in order to create LNPs which could safely pass through the cell membranes of living organisms. As of 2021, the current understanding of LNPs formulated with such ionizable cationic lipids is that they enter cells through receptor-mediated endocytosis and end up inside endosomes. The acidity inside the endosomes causes LNPs' ionizable cationic lipids to acquire a positive charge, and this is thought to allow LNPs to escape from endosomes and release their RNA payloads. From 2005 into the early 2010s, LNPs were investigated as a drug delivery system for small interfering RNA (siRNA) drugs.
== Legacy == During his post-doctoral days in the US, Rao's researches were focused on the synthesis of melanin pigments as well as on the carcinoma cells of human breast and the cross-talk between growth factor and steroid receptors. The group led by him is credited with the discovery of a novel subset of IgD receptors on 'naive' B lymphocytes which helped in a wider understanding of antigen-specific B cell selection and amplification. Later, furthering his earlier researches, he worked on designing new synthetic peptide vaccines for Hepatitis B which were reported to generate high immunogenicity in humans. He is also known to have contributed in the pathogenesis of Mycobacterium tuberculosis and in the diagnostics of HIV/AIDS. It was during his period with Virander Singh Chauhan and Ranjan Kumar Nanda at ICGEB, the group developed an electronic nose, a urine test, to monitor the progress of tuberculosis therapy. His current assignments are on the study of plasticity controlling mechanisms in receptor-initiated signaling pathways based on the systems level analysis of the antigen receptor-dependent signal transduction network. His research findings have been published as a number of articles; . He chaired U-EXCEL 2012, a task force of the Department of Biotechnology, for the North-eastern region of India and is a member of the Science and Engineering Research Board of the Department of Science and Technology. He is associated with the Institute of Life Sciences, Bhubaneswar as a member of its Scientific Advisory Committee and has delivered lectures on its behalf.
GLP-1 Formula – a formulation intended to support endogenous glucagon-like peptide-1 (GLP-1) activity. The GLP-1 Formula is a proprietary blend of plant extracts, probiotics, and prebiotics developed to support endogenous glucagon-like peptide-1 (GLP-1) activity. GLP-1 is a hormone secreted by intestinal L-cells in response to food intake that regulates insulin secretion, suppresses glucagon release, reduces appetite, and slows gastric emptying. TCI leveraged its Bio-Resource Data Mining technology to identify natural active compounds, and subsequently developed the formula through in-vitro validations and human trials. In-vitro studies indicated that the formula stimulates natural GLP-1 secretion from intestinal L-cells, which TCI reported to support stable blood glucose levels, enhances fat metabolism, and may induce white fat browning. SugarLock – a botanical extract designed to modulate postprandial glucose response. It is described as a proprietary, polyphenol-rich, allergen-free extract, and in clinical evaluation over a six-week intervention period was shown to support fasting blood glucose, decrease body fat, and attenuate postprandial blood sugar spikes. Outcomes were further validated through continuous glucose monitoring (CGM). TCI has positioned SugarLock as an ingredient for brands targeting glycemic control and metabolic health applications. The ingredient was featured at SupplySide Global 2025, where TCI's Chief Product Officer presented clinical findings from the intervention study.
Sources: en.wikipedia.org
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.
A high main-peak percentage says little about identity, counter-ion content, or residual solvents. It also does not distinguish an isomer or a closely eluting analog. Mass confirmation and the accompanying documentation cover those gaps.
Salt form changes mass, solubility, and hygroscopicity, and acetate and trifluoroacetate salts behave differently in solution. Storage guidance still centers on -20 °C for powder and lower temperatures for solutions. The certificate should state which salt is present.
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。