A practical reference on synthetic heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-08-18 and is reviewed periodically as new material appears.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
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.
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.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Seven-residue peptide |
| Molecular mass | 813.9 Da | Monoisotopic value |
| Appearance | White to off-white powder | Lyophilized form |
| Solubility | Freely soluble in water | Also soluble in saline and polar solvents |
| Storage (dry) | -20 °C or lower | Desiccated, protected from light |
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.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
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。
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。
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
== Physical properties and technological applications == Evidence exists for a highly cross-linked heteropolymer bound covalently to matrix scaffolding melanoproteins. It has been proposed that the ability of melanin to act as an antioxidant is directly proportional to its degree of polymerization or molecular weight. Suboptimal conditions for the effective polymerization of melanin monomers may lead to formation of pro-oxidant melanin with lower-molecular-weight, implicated in the causation and progression of macular degeneration and melanoma. Signaling pathways that upregulate melanization in the retinal pigment epithelium (RPE) also may be implicated in the downregulation of rod outer segment phagocytosis by the RPE. This phenomenon has been attributed in part to foveal sparing in macular degeneration.
Byzantine music is eclectically descended from early Christian plainsong, Jewish music, and a variety of ancient music; its exact connections to ancient Greek music remain uncertain. It included both sacred and secular traditions, but the latter is little known, whereas the former remains the central music of Eastern Orthodox liturgy into the 21st century. The empire's church music, known as Byzantine chant, was exclusively unaccompanied monodic vocal music, sung in Greek. From the 8th century, chant melodies were governed by the Oktōēchos framework, a set of eight modes—echos (ἦχος; lit. 'sound')—which each provide predetermined motivic formulae for composition. These formulae were chosen for proper text stress and occasionally for text painting, then collated through centonisation into hymns or psalms. Byzantine chant was central to the Byzantine Rite; the earliest music was not notated, including early monostrophic short hymns like the troparion. Proto-Ekphonetic notation (9th century onwards) marked simple recitation patterns. The neumatic Palaeo-Byzantine notation system emerged in the 10th century, and the Middle Byzantine "Round Notation" from the mid-12th century onwards is the first fully diastematic scheme. Several major forms developed alongside well-known composers: the long kontakion (5th century onwards), popularised by Romanos the Melodist; the also-extensive kanōn (late 7th century onwards), developed by Andrew of Crete; and the shorter sticheron (at least 8th century onwards), championed by Kassia.
Tomatoes were not grown in England until the 1590s. One of the earliest cultivators was John Gerard, a barber-surgeon. Gerard's Herbal, published in 1597, and largely plagiarized from continental sources, is also one of the earliest discussions of the tomato in England. Gerard knew the tomato was eaten in Spain and Italy. Nonetheless, he believed it was poisonous. Gerard's views were influential, and the tomato was considered unfit for eating for many years in Britain and its North American colonies. By 1820, tomatoes were described as "to be seen in great abundance in all our vegetable markets" and to be "used by all our best cooks", reference was made to their cultivation in gardens still "for the singularity of their appearance", while their use in cooking was associated with exotic Italian or Jewish cuisine. For example, in Elizabeth Blackwell's A Curious Herbal, it is described under the name "Love Apple (Amoris Pomum)" as being consumed with oil and vinegar in Italy, similar to consumption of cucumbers in the UK. In 1963, The New York Times gave an explanation of the name 'Love Apple' as a French misreading of the Italian pomo dei Mori ("the Moors' apple") as pomme d'amour, ("apple of love").
== Definition == The shutdown margin for nuclear reactors (that is, when the reactor is considered to be safely in a shutdown state) is usually defined either in terms of reactivity or dollars. For reactivity, this is calculated in units of delta-k/k, where k is equal to the criticality of the reactor (essentially, how fast and controlled the nuclear fission reaction is). It is sometimes also measured in dollars, where one dollar is equal to a reactor in prompt criticality, this can then be used to calculate the change in reactivity required to shut down or start up the reactor. The shutdown margin for each reactor can either refer to the margin by which a reactor is subcritical with all its control rods inserted, or as the margin by which the reactor would be shut down in the event of a SCRAM. This margin has to be considered carefully for each reactor and reactor design, to ensure that it remains within the technical specifications and limitations of the reactor.
Sources: en.wikipedia.org
Although it may seem like a so-called disappearing polymorph can no longer be produced at all, it is believed that it is always possible in principle to reconstruct the original polymorph in a lab that has not been contaminated by the new morph. This was demonstrated in the ranitidine case. However, doing so is usually impractical or uneconomical. In some cases, the original morph can be reconstructed by a different pathway with different chemical kinetics, as in the case of progesterone. This is of concern to the pharmaceutical industry, where disappearing polymorphs can ruin the effectiveness of their products and make it impossible to manufacture the original product if there is any contamination. There have been cases in which a laboratory that attempted to reproduce crystals of a particular structure instead grew not the original but a new crystal structure. The drug paroxetine was subject to a lawsuit that hinged on such a pair of polymorphs, and multiple life-saving drugs, such as ritonavir, have been recalled due to unexpected polymorphism.
=== McLafferty rearrangement === The McLafferty rearrangement can occur in a molecule containing a keto-group and involves β-cleavage, with the gain of the γ-hydrogen atom. Ion-neutral complex formation involves bond homolysis or bond heterolysis, in which the fragments do not have enough kinetic energy to separate and, instead, reaction with one another like an ion-molecule reaction.
In transportation, cargo refers to goods transported by land, water, or air, while freight refers to its conveyance. In economics, freight refers to goods transported at a freight rate for commercial gain. The term cargo is also used in the case of goods in the cold-chain, because the perishable inventory is always in transit towards a final end-use, even when it is held in cold storage or other similar climate-controlled facilities, including warehouses. Multi-modal container units, designed as reusable carriers to facilitate unit load handling of the goods contained, are also referred to as cargo, especially by shipping lines and logistics operators. When empty containers are shipped each unit is documented as a cargo and when goods are stored within, the contents are termed containerized cargo. Similarly, aircraft ULD boxes are also documented as cargo, with an associated packing list of the items contained within.
=== Manual solutions === Manual methods such as HEPA filtered vacuuming serves as a backup to eliminating mold via environmental control. HEPA vacuums possess air filters that do not allow mold to be spread into the air again. Installing drying fans, wiping dry books and surrounding furniture, as well as air ducts and shelves will also help to prevent further infestations. In extreme cases, some books and items are discarded to protect the rest of the collection from being affected. These preservation activities are provided by available library staff or hired contractors.
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Sources: en.wikipedia.org
pleomorphism 1. Variability in the size, shape, or staining of cells and/or their nuclei, particularly as observed in histology and cytopathology, where morphological variation is frequently an indicator of a cellular abnormality such as disease or tumor formation. 2. In microbiology, the ability of some microorganisms such as certain bacteria and viruses to alter their morphology, metabolism, or mode of reproduction in response to changes in their environment.
=== Geophysics === Beneath the Earth's mantle lies the core, which is made up of two parts: the solid inner core and the liquid outer core. Both contain significant quantities of iron. The liquid outer core moves in the presence of the magnetic field, and eddies are generated within it due to the Coriolis effect. These eddies develop a magnetic field that boosts Earth's original magnetic field, a self-sustaining process known as the geomagnetic dynamo.
=== 18 July === In Crimea, the Russian-installed governor of Sevastopol claimed that a naval drone was intercepted while attempting to attack the city. SBU naval and aerial drones also attacked a Russian coast guard base on Lake Donuzlav during a Russian naval exercise, hitting the base headquarters, ammunition depot, a power substation and technical facilities. Ukraine claimed to have shot down a Russian drone over Kyiv with no casualties recorded. The Freedom of Russia Legion claimed to have launched an attack on the Bolshoye Savino airport in Perm hosting MiG-31 fighters. A video released showed two KAMAZ trucks burning, with the group claiming to have destroyed “several units of military equipment.” Ukrainian Prime Minister Denys Shmyhal announced the extension of a system to jam Russian TV and radio broadcasts into Donetsk, Mykolaiv, Kherson, and Zaporizhzhia Oblasts.
Conway became the chairman of Anthrocon in 1999, after his invitation as a guest of honor in 1998. Under his leadership, Anthrocon was incorporated and moved to Philadelphia. The convention's attendance grew from 842 to 2,489 over the period from 1999 to 2006, necessitating a further move to Pittsburgh; 3,390 attended in 2008. Conway is the public face of Anthrocon, responsible for public relations, negotiating hotel contracts, managing finances, damage control and other activities before, during and after the convention. He also talks to fans about presenting furry fandom to the public.
Sources: en.wikipedia.org
It is a synthetic peptide of seven amino acids. Its backbone corresponds to a fragment of adrenocorticotropic hormone extended at the carboxyl end. The material is distributed as a lyophilized solid for laboratory use.
The extension was introduced to slow enzymatic breakdown of the peptide in biological systems. Natural ACTH fragments are degraded rapidly by peptidases. Adding the tripeptide was intended to extend the window during which the molecule remains intact.
Most published work consists of animal experiments conducted in a small number of laboratories. Human data are limited in number and size. Whether the observed effects translate into reliable clinical benefit is still unresolved.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.