The short version of melanocortin signalling fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-21 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.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
| 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 |
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.
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
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.
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
== Drying defects == Drying defects are the most common form of degrade in timber, next to natural problems such as knots. There are two types of drying defects, although some defects involve both causes:
Intending to wrest back the initiative, sever UNITA's logistics lifelines to South West Africa and Zaire, and forestall any future insurgent offensives, FAPLA launched Operation Saluting October in mid-1987. The impetus for Saluting October likely originated with the Soviet military mission, which pressed the idea of a major conventional thrust to destroy UNITA's southeastern front as early as 1983. It had received a new commander that year, Lieutenant General Pyotr Gusev, former deputy commander of the Carpathian Military District. In light of the war's length, its cost, the rising death toll, and looming cuts in the Soviet military expenditure which would limit future efforts to support FAPLA's war effort, Gusev wanted a decisive multi-divisional offensive to crush UNITA once and for all. Operation Saluting October was a two-pronged offensive aimed at retaking three major settlements from UNITA, Cangamba, Cassamba, and Mavinga. The FAPLA command staff intended the attack on Cangamba and Cassamba as a feint, hoping to draw UNITA forces there and away from Mavinga. Once Mavinga was in government hands, FAPLA could expel the remaining insurgents from Moxico Province and pave the way for a final assault on Savimbi's headquarters at Jamba. Between 4 and 9 Soviet advisers were to be attached on the battalion level, albeit with strict orders not to participate in the fighting and withdraw from the front as necessary to avoid contact with UNITA. They were accompanied by a small number of Cuban advisers and East German technical personnel serving in a variety of support roles.
Heterologous vaccines also known as "Jennerian vaccines", are vaccines that are pathogens of other animals that either do not cause disease or cause mild disease in the organism being treated. The classic example is Jenner's use of cowpox to protect against smallpox. A current example is the use of BCG vaccine made from Mycobacterium bovis to protect against tuberculosis.
=== US introduction === The Turkestan cockroach was first noticed in the US in 1978, around the former Sharpe Army Depot in California, followed shortly after by appearances at Fort Bliss in Texas and several other military bases. Researchers believe the species arrived on military equipment returning from Central Asia, perhaps Afghanistan. Since then the species has been rapidly replacing the common oriental cockroach (Blatta orientalis) in urban areas of the Southwestern United States “as the most important peri-domestic species”, with advantages of laying more eggs and maturing more quickly than the oriental cockroach. “They typically inhabit in-ground containers such as water meter, irrigation, and electrical boxes, raises of concrete, cracks and crevices, and hollow block walls.” They are well established in the Southwest and parts of the Southeast, and have been reported in the Northeast. It has become established in California.
Sources: en.wikipedia.org
There was a large outbreak of eosinophilia-myalgia syndrome (EMS) in the U.S. in 1989, with more than 1,500 cases reported to the CDC and at least 37 deaths. After preliminary investigation revealed that the outbreak was linked to intake of tryptophan, the U.S. Food and Drug Administration (FDA) recalled tryptophan supplements in 1989 and banned most public sales in 1990, with other countries following suit. Subsequent studies suggested that EMS was linked to specific batches of L-tryptophan supplied by a single large Japanese manufacturer, Showa Denko. It eventually became clear that recent batches of Showa Denko's L-tryptophan were contaminated by trace impurities, which were subsequently thought to be responsible for the 1989 EMS outbreak. However, other evidence suggests that tryptophan itself may be a potentially major contributory factor in EMS. There are also claims that a precursor reached sufficient concentrations to form a toxic dimer. The FDA loosened its restrictions on sales and marketing of tryptophan in February 2001, but continued to limit the importation of tryptophan not intended for an exempted use until 2005. The fact that the Showa Denko facility used genetically engineered bacteria to produce the contaminated batches of L-tryptophan later found to have caused the outbreak of eosinophilia-myalgia syndrome has been cited as evidence of a need for "close monitoring of the chemical purity of biotechnology-derived products".
On the basis of favorable early results, ongoing research is examining proposed psychedelic therapies for conditions including major depressive disorder, and anxiety and depression linked to terminal illness. The United States Food and Drug Administration has granted breakthrough therapy status, which expedites the assessment of promising drug therapies for potential approval, to psilocybin therapy for treatment-resistant depression and major depressive disorder. It has been proposed that psychedelics used for therapeutic purposes may act as active "super placebos". On the other hand, the inverse placebo effect (or "knowcebo" effect) caused by blinding failure may create an illusion of large effect sizes with psychedelics.
In February 2013, the Australian Sports Anti-Doping Authority (ASADA) and the World Anti-Doping Agency (WADA) began an investigation into the legality of Essendon's supplements program during the 2012 AFL season and the preceding preseason. Thirty-four Essendon players—including Watson—were suspected of taking the banned peptide Thymosin beta-4. This quickly led to debate over whether or not a guilty verdict would see Watson stripped of the medal. The investigation and court action stretched over the following four years. Initially, the AFL Tribunal delivered a not guilty verdict in March 2015, but on appeal in the Court of Arbitration for Sport (CAS), the players were found guilty in January 2016, resulting in the suspensions of all thirty-four players. An appeal lodged against that decision in the Federal Supreme Court of Switzerland was dismissed in October 2016. Following the guilty verdict handed down by the CAS in January, it was announced the AFL Commission would meet in February to determine whether Watson would retain his Brownlow Medal; however, this decision was delayed until the outcome of the Federal Supreme Court appeal. The final decision regarding Jobe Watson's Brownlow medal win was decided by the AFL Commission in late November 2016, with Watson retrospectively ruled ineligible for the award, and the medal then awarded to the next highest vote-getters, Cotchin and Mitchell, under the normal rules regarding ineligible players; Watson had pre-empted the decision by announcing on 11 November 2016 that he would hand back the medal.
==== Acetaminophen ==== One of the main types of drug studies conducted is using astronauts as test subjects and measuring drug dynamics before and after spacecraft flight. A study on acetaminophen pharmacokinetics was performed on ten astronauts, studying its concentration dynamics in saliva two months before spaceflight and during long-term spaceflight. Saliva samples were analyzed at intervals of 0.017, 0.33, 0.5, 0.75, 1, 2, 4, and 6 hours after acetaminophen intake by HPLC with UV spectrophotometric detection at 254 nm. The absorption of acetaminophen during spaceflight was delayed after tablet administration and the bioavailability of the encapsulated drug was found to be moderately decreased. Additionally, the half-life of encapsulated acetaminophen was prolonged during spaceflight.
The Trp-His cross-link is addressed by Castle and coworkers, who used oxidative coupling by NCS to form the C-N linkage. To prevent over-chlorination, NCS was incubated with Pro-OBn, which reacts with NCS so as to modulate its concentration. This method of cross-linking tryptophan and histidine was used in subsequent total synthesis efforts.
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.
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.