The short version of Reversed-phase HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-01. Anything still debated is marked as such rather than presented as settled.
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. 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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | ≥ 95 % of peak area by HPLC | Some suppliers quote 98 % or higher |
| Identity confirmation | Mass spectrometry (electrospray or MALDI) | Observed mass is compared with the calculated mass |
| Common analytical method | Reversed-phase HPLC on a C18 column | Acetonitrile and water gradients with trifluoroacetic acid |
| Primary degradation route | Oxidation of the methionine residue | Yields a sulfoxide that separates cleanly on chromatography |
| Storage of dissolved material | Aliquoted and frozen at −20 °C or below | Single-use aliquots avoid repeated temperature cycling |
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 is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
== Development and current usage == Livia S. Eberlin, Ph.D., an Assistant Professor of Chemistry at the University of Texas at Austin, first reported the invention of the MasSpec Pen in 2017. Within her laboratory, the device has been used to analyze human tissue biopsies, including normal and cancerous breast, lung, ovarian, and thyroid samples. The MasSpec Pen is currently being evaluated for use on freshly excised tissue biopsies and for intraoperative use during oncology surgeries. The MasSpec Pen has been licensed to Genio Technologies, Inc., a subsidiary of MS Pen Technologies, Inc.
== Environmental Impact == Parcel to pallet sized insulated shipping containers have historically been single-use products due to the low-cost material composition of EPS and water-based gel packs. The insulation material typically finds its way into landfill streams as it is not readily recyclable in the United States. The development of reusable high-performance shipping containers have been shown to reduce packing waste by 95% while also contributing significant savings to other environmental pollutants.
Bravo company carried out reconnaissance operations around Najaf On March 22, 2003, after a number of delays, the majority of 2nd and 3rd battalions, 10th SFG, were airlifted into northern Iraq, with the rest arriving the following day, marking the beginning of operations in northern Iraq – On March 28, 3rd Battalion, 10th SFG, with Kurdish Peshmerga elements, took part in Operation Viking Hammer against the terrorist group Ansar al-Islam, killing 300 terrorists-largely and discovering evidence of al-Qaeda trying to produce chemical weapons. On 6 April 2003, ODA 391 and ODA 392 from the 3rd SFG and ODA 044 from 10th SFG with about 150 Kurdish fighters were the main force involved in the Battle of Debecka Pass, whilst other ODAs 051, 055, 056 and other ODAs from both groups with Kurdish forces took the town of Ayn Sifni – opening the road to Mosul. On 9 April, nine ODAs from FOB 103 encircled Kirkuk after fierce fighting to capture the ridges overlooking the approaches to the city, the earlier capture of the nearby city of Tuz had largely broken the will of the Iraqi Army and only the Fedayeen remained in Kirkuk, a week later the 173rd Airborne took over responsibility for the city and secured it. After several days of heavy airstrikes, FOB 102 and their Peshmerga allies took Mosul unopposed and were relieved by 3rd Battalion, 3rd SFG, conventional Army and Marine forces.
Sources: en.wikipedia.org
=== Commercialization === Elbasvir/grazoprevir was FDA approved in the United States, and has been approved for use in the European Union, Canada, Japan, Australia, Saudi Arabia, Israel, and Switzerland. Zepatier is one of a few non-interferon therapies that are market-available. Competing treatments include Gilead's Harvoni (sofosbuvir and ledipasvir) and AbbVie's Viekira Pak (ombitasvir, paritaprevir, and ritonavir). Sale projections for Zepatier are $636 million in 2016 and rising to $1.5 billion by 2020. With Merck's release of Zepatier early in 2016, they saw large bumps in share prices in quarters 1 and 2, but are expected to drop down a bit. Zepatier does not have as strong a market hold as other competitive HCV treatments.
==== 2009–2015 ==== The JWP published its report on elements 113–116 and 118 in 2011. It recognised the JINR–LLNL collaboration as having discovered elements 114 and 116, but did not accept either team's claim to element 113 and did not accept the JINR–LLNL claims to elements 115 and 118. The JINR–LLNL claim to elements 115 and 113 had been founded on chemical identification of their daughter dubnium, but the JWP objected that current theory could not distinguish between superheavy group 4 and group 5 elements by their chemical properties with enough confidence to allow this assignment. The decay properties of all the nuclei in the decay chain of element 115 had not been previously characterised before the JINR experiments, a situation which the JWP generally considers "troublesome, but not necessarily exclusive", and with the small number of atoms produced with neither known daughters nor cross-reactions the JWP considered that their criteria had not been fulfilled. The JWP did not accept the Riken team's claim either due to inconsistencies in the decay data, the small number of atoms of element 113 produced, and the lack of unambiguous anchors to known isotopes. In early 2009, the Riken team synthesised the decay product 266Bh directly in the 248Cm + 23Na reaction to establish its link with 278113 as a cross-bombardment. They also established the branched decay of 262Db, which sometimes underwent spontaneous fission and sometimes underwent the previously known alpha decay to 258Lr.
Some slow cookers have lids that seal to prevent their contents from spilling during transport. The ability to food to be slow-cooked ahead of time is regarded by some cooks as convenient. Drawing little energy, it is used in some households so it can draw entirely on 1–2 kW solar panels during the day. Slow cookers are less dangerous than ovens or stove tops due to their lower operating temperatures and closed lids. However, they still contain a large amount of foods and liquids at temperatures close to boiling, and they can cause serious scalds if spilled.
High-dose or prolonged parenterally-administered lorazepam with its associated solvent can cause propylene glycol intoxication and poisoning. In September 2020, the US Food and Drug Administration (FDA) required the boxed warning be updated for all benzodiazepine medicines to describe the risks of abuse, misuse, addiction, physical dependence, and withdrawal reactions consistently across all the medicines in the class.
Sources: en.wikipedia.org
====== Allergology ====== To train in the add-on specialty of allergology a physician must first be a specialist in general practice, occupational and environmental medicine, pediatric allergology, endocrinology and diabetology, geriatrics, hematology, dermatology and venerology, internal medicine, cardiology, clinical immunology and transfusion medicine, pulmonology, medical gastroenterology and hepatology, nephrology or otorhinolaryngology.
Ribosomally synthesized and post-translationally modified peptides (RiPPs), also known as ribosomal natural products, are a diverse class of natural products of ribosomal origin. Consisting of more than 20 sub-classes, RiPPs are found in all three domains of life, and they possess a wide range of biological functions. As a consequence of the falling cost of genome sequencing, scientific interest in RiPPs has increased in the last few decades. Because RiPPs are more closely predictable from raw genomic data than other natural products (e.g. alkaloids and terpenoids), their presence in sequenced organisms can, in theory, be identified rapidly. This makes RiPPs an attractive target of modern natural product discovery efforts.
CO2 + NH+4 + N5,N10-methylene tetrahydrofolate + NADH + H+ ⇌ Glycine + tetrahydrofolate + NAD+ In addition to being synthesized from serine, glycine can also be derived from threonine, choline or hydroxyproline via inter-organ metabolism of the liver and kidneys.
Sources: en.wikipedia.org
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.
The methionine residue at the start of the chain is vulnerable to oxidation, producing a sulfoxide variant. Amide bonds can also hydrolyze, though more slowly under neutral conditions. Cold storage, oxygen exclusion and minimization of freeze-thaw cycles slow both processes but do not stop them.
A purity number on a certificate does not establish that a powder is the same product as a registered nasal medicine. Counter-ion content, residual solvents and peptide-related impurities may differ between the two. Independent verification is the only way to narrow that gap.
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.