If you have been reading about peptide synthesis 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.
Updated 2026-01-11. Numbers and descriptions here follow the published literature rather than marketing material.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | ACTH(4-7) analogue |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Free N terminus, unmodified side chains |
| Molecular weight | 813.9 Da | Free base; salt forms differ |
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility | Freely soluble in water | Hydrophilic; polar solvents preferred |
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.
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.
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.
=== Systemic lupus erythematosus === The role of Th22 cells in systematic lupus erythematous (SLE) is still unclear. In some patients levels of Th22 cells and interleukin-22 (IL-22) were increased, which correlated with disease activity, but decreased levels of interleukin-22 (IL-22) and Th22 cells were also reported. Interleukin-22 (IL-22) is a cytokine involved in recruiting neutrophils in response to microbe invading, and in the case of lupus, it seems that interleukin 22 (IL-22) is involved in inflammatory and pathological processes via recruiting of immune cells. On the other hand, Th22 cells might be a better predictor of systematic lupus erythematous (SLE) development than Th17 cells.
== Heavy-duty vehicles == U.S. National Highway Traffic Safety Administration regulations only apply to vehicles under 10,000 pounds. For heavy-duty vehicles (Classes 7 and 8, gross vehicle weight greater than 26,000 pounds), which are central to fleet management, most of the above-mentioned systems don't work well, requiring the development of other systems. The US Department of Transportation has commissioned several studies to find systems that work on the heavy-duty market specifying some goals that were needed in this market. The SAE has tried to disseminate best practices since legal regulations for heavy vehicles has been lagging.
=== Bacteria === Three species of bacteria, Carnobacterium pleistocenium, Chryseobacterium greenlandensis, and Herminiimonas glaciei, have reportedly been revived after surviving for thousands of years frozen in ice. Certain bacteria, notably Pseudomonas syringae, produce specialized proteins that serve as potent ice nucleators, which they use to force ice formation on the surface of various fruits and plants at about −2 °C. The freezing causes injuries in the epithelia and makes the nutrients in the underlying plant tissues available to the bacteria. Listeria grows slowly in temperatures as low as -1.5 °C and persists for some time in frozen foods.
These include agents that increase insulin release (sulfonylureas), agents that decrease absorption of sugar from the intestines (acarbose), agents that inhibit the enzyme dipeptidyl peptidase-4 (DPP-4) that inactivates incretins such as GLP-1 and GIP (sitagliptin), agents that make the body more sensitive to insulin (thiazolidinedione) and agents that increase the excretion of glucose in the urine (SGLT2 inhibitors). When insulin is used in type 2 diabetes, a long-acting formulation is usually added initially, while continuing oral medications. Some severe cases of type 2 diabetes may also be treated with insulin, which is increased gradually until glucose targets are reached.
Sources: en.wikipedia.org
== Chemistry == Tadalafil is an annulated 2,5-diketopiperazine. It is also a 1,2,3,4-tetrahydro-β-carboline. Tadalafil can be synthesized starting from (D)-tryptophan methyl ester and piperonal via a Pictet–Spengler reaction. This is followed by condensations with chloroacetyl chloride and methylamine to complete the diketopiperazine ring:
Angelicin synthase is a cytochrome P450 protein containing heme, isolated from parsnip. It uses molecular oxygen for the oxidation and requires a partner cytochrome P450 reductase for functional expression. This uses nicotinamide adenine dinucleotide phosphate.
In the following days, moral support was followed by material support. Large quantities of food, medicine, clothing, medical equipment, and other humanitarian aid were sent to Romania. Around the world, the press dedicated entire pages and sometimes even complete issues to the Romanian revolution and its leaders. On 24 December, Bucharest was still a city at war. Tanks, APCs and trucks continued to patrol the city and surround trouble spots in order to protect them. At intersections near strategic objectives, roadblocks were built; automatic gunfire continued in and around University Square, the Gara de Nord (the city's main railroad station) and Palace Square. Yet amid the chaos, some people were seen clutching makeshift Christmas trees. Doctors at one Bucharest hospital reported not sleeping for days and treating as many as 3,000 civilians due to the fighting. "Terrorist activities" continued until 27 December, when they abruptly stopped. Nobody ever found out who conducted them, or who ordered them stopped. The Central University Library was burned down in uncertain circumstances and over 500,000 books, along with about 3,700 manuscripts, were destroyed.
In December 2016, Chipotle announced that co-CEO Monty Moran had stepped down from his role effective immediately with Ells becoming the sole CEO. Eleven months later, Ells announced in November 2017 that he would be stepping down as CEO. In December 2017, Chipotle announced it signed a 15-year lease and in late 2018 will move around 450 corporate employees—currently housed in multiple buildings around downtown Denver—into the new 1144 Fifteenth Tower and occupy around 126,000 square feet, or 5 floors, of the 40-story tower. In February 2018, Chipotle announced that Taco Bell CEO Brian Niccol would replace Ells as CEO starting on March 5 while Ells would retain his chairman position. Many industry analysts praised Niccol's appointment saying that Chipotle "needed new blood". Chipotle stock went up $30.27, or 12.04%, as a result of the announcement. However, other analysts criticized the announcement by saying that "the move goes against everything the burrito chain stands for". In May 2018, Chipotle announced that it would relocate its headquarters from Denver to Newport Beach, California. Corporate functions handled in their Denver and New York offices would move to Newport Beach or to an existing office in Columbus, Ohio. This move would impact 400 workers, some being offered relocation and retention packages. In May 2018, Chipotle announced the "Chipotlane" and began testing it in the U.S.
The aseptic technique during insertion and handling has been shown to decrease the occurrence of these complications. Also, in some cases of infection, antibiotics could be given through the ICV system, avoiding the need for removal.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.
It contains the 4-7 fragment of adrenocorticotropic hormone extended at the C terminus. That truncation removes the region associated with steroidogenic activity. The design intent was to keep neurotrophic properties while avoiding full hormonal effects.
No natural source of the intact heptapeptide is known. It is produced by solid-phase peptide synthesis. Some related ACTH fragments arise as hormone processing products, but the Pro-Gly-Pro extension is a designed addition rather than a natural sequence.
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.