If you have been reading about heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-01-27. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Heptapeptide; ACTH(4-10) analog extended at C-terminus |
| Molecular mass | ~813.9 Da | Free peptide, unmodified |
| Appearance | White to off-white powder | Typical lyophilized solid |
| Solubility | Soluble in water and saline | Also soluble in common aqueous buffers |
| Storage (solid) | -20 °C, desiccated | Protect from moisture and repeated thawing |
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.
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.
Biological research in cold seeps and hydrothermal vents has been mostly focused on the microbiology and the prominent macro-invertebrates thriving on chemosynthetic microorganisms. Much less research has been done on the smaller benthic fraction at the size of the meiofauna (<1 mm). A community composition's orderly shift from one set of species to another is called ecological succession. The first type of organism to take advantage of this deep-sea energy source is bacteria. Aggregating into bacterial mats at cold seeps, these bacteria metabolize methane and hydrogen sulfide (another gas that emerges from seeps) for energy. This process of obtaining energy from chemicals is known as chemosynthesis.
== Criticism == Some of the early MRE main courses were not very palatable, earning them the nicknames "Meals Rejected by Everyone", "Meals Rejected by Ethiopians" (during the 1983–1985 famine in Ethiopia), or "Meals Rarely Edible". Some individual portions had their own nicknames. For example, the frankfurters, which came sealed in pouches of four, were referred to as "the four fingers of death". Although quality has improved over the years, many of the nicknames have stuck. MREs were sometimes called "Three Lies for the Price of One ... it's not a Meal, it's not Ready, and you can't Eat it." As late as the 2010 deployment to Afghanistan, one veteran in November 2019 characterized MREs (the traditional Thanksgiving meal had been destroyed in an attack, and the standard MRE shipment partially destroyed) as "accursed things". Their low dietary fiber content could cause constipation in some, so they were also known as "Meals Requiring Enemas", "Meals Refusing to Exit", "Meals Refusing to Excrete", "Massive Rectal Expulsions", or "Meals Regurgitated Easily". While the laxative effect of xylitol sweetener (if excessively consumed) may contribute to a myth that the gum found in MREs contains a laxative, the crackers in the ration pack do contain a higher-than-normal vegetable content to facilitate digestion. In December 2006, comedian Al Franken (on his eighth United Service Organizations tour at the time) joked to troops in Iraq that he had his fifth MRE so far and "none of them had an exit strategy".
==== Complex II ==== In Complex II (succinate dehydrogenase or succinate-CoQ reductase; EC 1.3.5.1) additional electrons are delivered into the quinone pool (Q) originating from succinate and transferred (via flavin adenine dinucleotide (FAD)) to Q. Complex II consists of four protein subunits: succinate dehydrogenase (SDHA); succinate dehydrogenase [ubiquinone] iron–sulfur subunit mitochondrial (SDHB); succinate dehydrogenase complex subunit C (SDHC); and succinate dehydrogenase complex subunit D (SDHD). Other electron donors (e.g., fatty acids and glycerol 3-phosphate) also direct electrons into Q (via FAD). Complex II is a parallel electron transport pathway to Complex I, but unlike Complex I, no protons are transported to the intermembrane space in this pathway. Therefore, the pathway through Complex II contributes less energy to the overall electron transport chain process.
=== Mechanistic role in LTP === There is strong evidence that after activation of CaMKII, CaMKII plays a role in the trafficking of AMPA receptors into the membrane and then the PSD of the dendrite. Movement of AMPA receptors increases postsynaptic response to presynaptic depolarization through strengthening the synapses. This produces LTP. Mechanistically, CaMKII phosphorylates AMPA receptors at the P2 serine 831 site. This increases channel conductance of GluA1 subunits of AMPA receptors, which allows AMPA receptors to be more sensitive than normal during LTP. Increased AMPA receptor sensitivity leads to increased synaptic strength. In addition to increasing the channel conductance of GluA1 subunits, CaMKII has also been shown to aid in the process of AMPA receptor exocytosis. Reserve AMPA receptors are embedded in endosomes within the cell. CaMKII can stimulate the endosomes to move to the outer membrane and activate the embedded AMPA receptors. Exocytosis of endosomes enlarges and increases the number of AMPA receptors in the synapse. The greater number of AMPA receptors increases the sensitivity of the synapse to presynaptic depolarization, and generates LTP.
Sources: en.wikipedia.org
Treatments are available to reduce the severity of some HD symptoms. For many of these treatments, evidence to confirm their effectiveness in treating symptoms of HD specifically are incomplete. As the disease progresses, the ability to care for oneself declines, and carefully managed multidisciplinary caregiving becomes increasingly necessary. Although relatively few studies of exercises and therapies have shown to be helpful to rehabilitate cognitive symptoms of HD, some evidence shows the usefulness of physical therapy, occupational therapy, and speech therapy.
The Truman Show was a commercial success, grossing $264 million worldwide against a budget of $60 million. A Film4 critic stated that the film "allows Carrey to edge away from broad comedy", adding that it was "a hilarious and breathtakingly conceived satire". That same year, Carrey appeared as a fictionalized version of himself on the final episode of Garry Shandling's The Larry Sanders Show, in which he deliberately ripped into Shandling's character. In 1999, Carrey had the lead role in Man on the Moon. He portrayed comedian Andy Kaufman to critical acclaim and received his second Golden Globe in a row but again failed to be nominated for an Academy Award. In addition, he received his first Screen Actors Guild Award nomination for Best Actor.
Mecasermin, sold under the brand name Increlex, also known as recombinant human insulin-like growth factor-1 (rhIGF-1), is a recombinant form of human insulin-like growth factor 1 (IGF-I) which is used in the long-term treatment of growth failure and short stature in children with severe primary IGF-I deficiency, for instance due to growth hormone deficiency or Laron syndrome (growth hormone insensitivity). Mecasermin has a biological half-life of about 5.8 hours in children with severe primary IGF-1 deficiency. A related medication is mecasermin rinfabate (brand name Iplex), which is a combination of mecasermin (rhIGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and insulin-like growth factor binding protein acid labile subunit (IGFALS) as a ternary complex. The complex serves to prolong the action of mecasermin in the human body; the half-life of mecasermin when provided as this complex is 13.4 hours in individuals with severe primary IGF-1 deficiency. Mecasermin therapy has been also shown to be beneficial in other conditions not related to growth failure, including diabetes mellitus and anorexia nervosa.
==== Reactive oxygen species ==== α-Ketoglutarate is one of the non-enzymatic antioxidant agents. It reacts with hydrogen peroxide (H2O2) to form succinate, carbon dioxide (i.e., CO2), and water (i.e., (H2O) thereby lowering the levels of H2O2. Additionally, α-ketoglutarate increases the activity of superoxide dismutase, which converts the highly toxic (O−2) radical to molecular oxygen (i.e., O2) and H2O2.
Pests that can afflict tea plants include mosquito bugs, genus Helopeltis, which are true bugs and not to be confused with dipterous insects of family Culicidae ('mosquitos'). Mosquito bugs can damage leaves both by sucking plant materials, and by the laying of eggs (oviposition) within the plant. Spraying with synthetic insecticides may be deemed appropriate. Other pests are Lepidopteran leaf feeders and various tea diseases.
Sources: en.wikipedia.org
Semax is a synthetic seven-amino-acid peptide derived from a fragment of corticotropin. It is used in Russia as a nasal preparation, while elsewhere it is studied as a research compound. It is not approved as a medicine in most countries.
Its sequence corresponds to the 4-10 region of corticotropin extended by three residues. This fragment lacks the region responsible for adrenal steroid release, so it is explored for neural rather than hormonal effects. The relationship explains the compound's classification among ACTH-derived peptides.
It holds approval in Russia for several neurological indications as a nasal spray or drop formulation. Regulatory agencies in the United States and the European Union have not approved it. Products sold elsewhere are generally labeled for research use only.
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.